Internet Engineering Task Force W. Wang
Internet-Draft Zhejiang Gongshang University
Intended status: Standards Track E. Haleplidis
Expires: April 27, 2012 University of Patras
K. Ogawa
NTT Corporation
C. Li
Hangzhou BAUD Networks
J. Halpern
Ericsson
October 25, 2011
ForCES Logical Function Block (LFB) Library
draft-ietf-forces-lfb-lib-06
Abstract
This document defines basic classes of Logical Function Blocks (LFBs)
used in the Forwarding and Control Element Separation (ForCES). The
basic LFB classes are defined according to ForCES FE model and ForCES
protocol specifications, and are scoped to meet requirements of
typical router functions and considered as the basic LFB library for
ForCES. The library includes the descriptions of the LFBs and the
XML definitions.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 27, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Table of Contents
1. Terminology and Conventions . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1. Scope of the Library . . . . . . . . . . . . . . . . . . 8
3.2. Overview of LFB Classes in the Library . . . . . . . . . 10
3.2.1. LFB Design Choices . . . . . . . . . . . . . . . . . 10
3.2.2. LFB Class Groupings . . . . . . . . . . . . . . . . . 10
3.2.3. Sample LFB Class Application . . . . . . . . . . . . 12
3.3. Document Structure . . . . . . . . . . . . . . . . . . . 13
4. Base Types . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1. Data Types . . . . . . . . . . . . . . . . . . . . . . . 15
4.1.1. Atomic . . . . . . . . . . . . . . . . . . . . . . . 15
4.1.2. Compound struct . . . . . . . . . . . . . . . . . . . 16
4.1.3. Compound array . . . . . . . . . . . . . . . . . . . 16
4.2. Frame Types . . . . . . . . . . . . . . . . . . . . . . . 17
4.3. MetaData Types . . . . . . . . . . . . . . . . . . . . . 17
4.4. XML for Base Type Library . . . . . . . . . . . . . . . . 18
5. LFB Class Description . . . . . . . . . . . . . . . . . . . . 40
5.1. Ethernet Processing LFBs . . . . . . . . . . . . . . . . 40
5.1.1. EtherPHYCop . . . . . . . . . . . . . . . . . . . . . 41
5.1.2. EtherMACIn . . . . . . . . . . . . . . . . . . . . . 43
5.1.3. EtherClassifier . . . . . . . . . . . . . . . . . . . 44
5.1.4. EtherEncap . . . . . . . . . . . . . . . . . . . . . 47
5.1.5. EtherMACOut . . . . . . . . . . . . . . . . . . . . . 49
5.2. IP Packet Validation LFBs . . . . . . . . . . . . . . . . 50
5.2.1. IPv4Validator . . . . . . . . . . . . . . . . . . . . 50
5.2.2. IPv6Validator . . . . . . . . . . . . . . . . . . . . 52
5.3. IP Forwarding LFBs . . . . . . . . . . . . . . . . . . . 53
5.3.1. IPv4UcastLPM . . . . . . . . . . . . . . . . . . . . 54
5.3.2. IPv4NextHop . . . . . . . . . . . . . . . . . . . . . 56
5.3.3. IPv6UcastLPM . . . . . . . . . . . . . . . . . . . . 58
5.3.4. IPv6NextHop . . . . . . . . . . . . . . . . . . . . . 60
5.4. Redirect LFBs . . . . . . . . . . . . . . . . . . . . . . 62
5.4.1. RedirectIn . . . . . . . . . . . . . . . . . . . . . 62
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5.4.2. RedirectOut . . . . . . . . . . . . . . . . . . . . . 63
5.5. General Purpose LFBs . . . . . . . . . . . . . . . . . . 64
5.5.1. BasicMetadataDispatch . . . . . . . . . . . . . . . . 64
5.5.2. GenericScheduler . . . . . . . . . . . . . . . . . . 65
6. XML for LFB Library . . . . . . . . . . . . . . . . . . . . . 68
7. LFB Class Use Cases . . . . . . . . . . . . . . . . . . . . . 90
7.1. IPv4 Forwarding . . . . . . . . . . . . . . . . . . . . . 90
7.2. ARP processing . . . . . . . . . . . . . . . . . . . . . 91
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 94
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 95
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 96
10.1. LFB Class Names and LFB Class Identifiers . . . . . . . . 96
10.2. Metadata ID . . . . . . . . . . . . . . . . . . . . . . . 98
10.3. Exception ID . . . . . . . . . . . . . . . . . . . . . . 98
10.4. Validate Error ID . . . . . . . . . . . . . . . . . . . . 99
11. Security Considerations . . . . . . . . . . . . . . . . . . . 101
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 102
12.1. Normative References . . . . . . . . . . . . . . . . . . 102
12.2. Informative References . . . . . . . . . . . . . . . . . 102
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 103
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1. Terminology and Conventions
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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2. Definitions
This document follows the terminology defined by the ForCES protocol
in [RFC5810] and by the ForCES FE model in [RFC5812]. The
definitions below are repeated for clarity.
Control Element (CE) - A logical entity that implements the ForCES
protocol and uses it to instruct one or more FEs on how to process
packets. CEs handle functionality such as the execution of
control and signaling protocols.
Forwarding Element (FE) - A logical entity that implements the
ForCES protocol. FEs use the underlying hardware to provide per-
packet processing and handling as directed/controlled by one or
more CEs via the ForCES protocol.
ForCES Network Element (NE) - An entity composed of one or more
CEs and one or more FEs. To entities outside an NE, the NE
represents a single point of management. Similarly, an NE usually
hides its internal organization from external entities.
LFB (Logical Function Block) - The basic building block that is
operated on by the ForCES protocol. The LFB is a well defined,
logically separable functional block that resides in an FE and is
controlled by the CE via ForCES protocol. The LFB may reside at
the FE's datapath and process packets or may be purely an FE
control or configuration entity that is operated on by the CE.
Note that the LFB is a functionally accurate abstraction of the
FE's processing capabilities, but not a hardware-accurate
representation of the FE implementation.
FE Model - The FE model is designed to model the logical
processing functions of an FE, which is defined by the ForCES FE
model document [RFC5812]. The FE model proposed in this document
includes three components; the LFB modeling of individual Logical
Functional Block (LFB model), the logical interconnection between
LFBs (LFB topology), and the FE-level attributes, including FE
capabilities. The FE model provides the basis to define the
information elements exchanged between the CE and the FE in the
ForCES protocol [RFC5810].
FE Topology - A representation of how the multiple FEs within a
single NE are interconnected. Sometimes this is called inter-FE
topology, to be distinguished from intra-FE topology (i.e., LFB
topology).
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LFB Class and LFB Instance - LFBs are categorized by LFB Classes.
An LFB Instance represents an LFB Class (or Type) existence.
There may be multiple instances of the same LFB Class (or Type) in
an FE. An LFB Class is represented by an LFB Class ID, and an LFB
Instance is represented by an LFB Instance ID. As a result, an
LFB Class ID associated with an LFB Instance ID uniquely specifies
an LFB existence.
LFB Metadata - Metadata is used to communicate per-packet state
from one LFB to another, but is not sent across the network. The
FE model defines how such metadata is identified, produced and
consumed by the LFBs. It defines the functionality but not how
metadata is encoded within an implementation.
LFB Component - Operational parameters of the LFBs that must be
visible to the CEs are conceptualized in the FE model as the LFB
components. The LFB components include, for example, flags,
single parameter arguments, complex arguments, and tables that the
CE can read and/or write via the ForCES protocol (see below).
LFB Topology - Representation of how the LFB instances are
logically interconnected and placed along the datapath within one
FE. Sometimes it is also called intra-FE topology, to be
distinguished from inter-FE topology.
Data Path - A conceptual path taken by packets within the
forwarding plane inside an FE. Note that more than one data path
can exist within an FE.
ForCES Protocol - While there may be multiple protocols used
within the overall ForCES architecture, the term "ForCES protocol"
and "protocol" refer to the Fp reference points in the ForCES
Framework in [RFC3746]. This protocol does not apply to CE-to-CE
communication, FE-to-FE communication, or to communication between
FE and CE managers. Basically, the ForCES protocol works in a
master-slave mode in which FEs are slaves and CEs are masters.
This document defines the specifications for this ForCES protocol.
LFB Port - A port refers to an LFB input port or output port. See
Section 3.2 of [RFC5812] for more detailed definitions.
Physical Port - A port refers to a physical media input port or
output port of an FE. A physical port is usually assigned with a
physical port ID, abbreviated with a PHYPortID. This document
mainly deals with physical ports with Ethernet media.
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Logical Port - A conceptually virtual port at data link layer (L2)
or network layer (L3). A logical port is usually assigned with a
logical port ID, abbreviated with a LogicalPortID. The logical
ports can be further categorized with a L2 logical port or a L3
logical port. An L2 logical port can be assigned with a L2
logical port ID, abbreviated with a L2PortID. An L3 logical port
can be assigned with a L3 logical port ID, abbreviated with a
L3PortID. MAC layer VLAN ports belongs to L2 logical ports as
well as logical ports.
LFB Class Library - The LFB class library is a set of LFB classes
that has been identified as the most common functions found in
most FEs and hence should be defined first by the ForCES Working
Group. The LFB Class Library is defined by this document.
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3. Introduction
[RFC5810] specifies Forwarding and Control Element Separation
(ForCES) framework. In the framework, Control Elements (CEs)
configure and manage one or more separate Forwarding Elements (FEs)
within a Network Element (NE) by use of a ForCES protocol. [RFC5810]
specifies the ForCES protocol. [RFC5812] specifies the Forwarding
Element (FE) model. In the model, resources in FEs are described by
classes of Logical Function Blocks (LFBs). The FE model defines the
structure and abstract semantics of LFBs, and provides XML schema for
the definitions of LFBs.
This document conforms to the specifications of the FE model
[RFC5812] and specifies detailed definitions of classes of LFBs,
including detailed XML definitions of LFBs. These LFBs form a base
LFB library for ForCES. LFBs in the base library are expected to be
combined to form an LFB topology for a typical router to implement IP
forwarding. It should be emphasized that an LFB is an abstraction of
functions rather than its implementation details. The purpose of the
LFB definitions is to represent functions so as to provide
interoperability between separate CEs and FEs.
More LFB classes with more functions may be developed in future time
and documented by IETF. Vendors may also develop proprietary LFB
classes as described in the FE model [RFC5812].
3.1. Scope of the Library
It is intended that the LFB classes described in this document are
designed to provide the functions of a typical router. [RFC5812]
specifies that a typical router is expected to provide functions to:
(1) Interface to packet networks and implement the functions
required by that network. These functions typically include:
* Encapsulating and decapsulating the IP datagrams with the
connected network framing (e.g., an Ethernet header and
checksum),
* Sending and receiving IP datagrams up to the maximum size
supported by that network, this size is the network's Maximum
Transmission Unit or MTU,
* Translating the IP destination address into an appropriate
network-level address for the connected network (e.g., an
Ethernet hardware address), if needed, and
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* Responding to network flow control and error indications, if
any.
(2) Conform to specific Internet protocols including the Internet
Protocol (IPv4 and/or IPv6), Internet Control Message Protocol
(ICMP), and others as necessary.
(3) Receive and forward Internet datagrams. Important issues in
this process are buffer management, congestion control, and
fairness.
* Recognizes error conditions and generates ICMP error and
information messages as required.
* Drops datagrams whose time-to-live fields have reached zero.
* Fragments datagrams when necessary to fit into the MTU of the
next network.
(4) Choose a next-hop destination for each IP datagram, based on the
information in its routing database.
(5) Usually support an interior gateway protocol (IGP) to carry out
distributed routing and reachability algorithms with the other
routers in the same autonomous system. In addition, some
routers will need to support an exterior gateway protocol (EGP)
to exchange topological information with other autonomous
systems. For all routers, it is essential to provide ability to
manage static routing items.
(6) Provide network management and system support facilities,
including loading, debugging, status reporting, exception
reporting and control.
The classical IP router utilizing the ForCES framework constitutes a
CE running some controlling IGP and/or EGP function or static route
setup and FEs implementing using Logical Function Blocks (LFBs)
conforming to the FE model[RFC5812] specifications. The CE, in
conformance to the ForCES protocol[RFC5810] and the FE model
[RFC5812] specifications, instructs the LFBs on the FE how to treat
received/sent packets.
Packets in an IP router are received and transmitted on physical
media typically referred to as "ports". Different physical port
media will have different ways for encapsulating outgoing frames and
decapsulating incoming frames. The different physical media will
also have different attributes that influence its behavior and how
frames get encapsulated or decapsulated. This document will only
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deal with Ethernet physical media. Other future documents may deal
with other types of media. This document will also interchangeably
refer to a port to be an abstraction that constitutes a PHY and a MAC
as described by the LFBs like EtherPHYCop, EtherMACIn, and
EtherMACOut.
IP packets emanating from port LFBs are then processed by a
validation LFB before being further forwarded to the next LFB. After
the validation process the packet is passed to an LFB where IP
forwarding decision is made. In the IP Forwarding LFBs, a Longest
Prefix Match LFB is used to look up the destination information in a
packet and select a next hop index for sending the packet onward. A
next hop LFB uses the next hop index metadata to apply the proper
headers to the IP packets, and direct them to the proper egress.
Note that in the process of IP packets processing, in this document,
we are adhering to the weak-host model [RFC1122] since that is the
most usable model for a packet processing Network Element.
3.2. Overview of LFB Classes in the Library
It is critical to classify functional requirements into various
classes of LFBs and construct a typical but also flexible enough base
LFB library for various IP forwarding equipments.
3.2.1. LFB Design Choices
A few design principles were factored into choosing how the base LFBs
looked like. These are:
o if a function can be designed by either one LFB or two or more
LFBs with the same cost, the choice is to go with two or more LFBs
so as to provide more flexibility for implementers.
o when flexibility is not required, an LFB should take advantage of
its independence as much as possible and have minimal coupling
with other LFBs. The coupling may be from LFB attributes
definitions as well as physical implementations.
o unless there is a clear difference in functionality, similar
packet processing should not be represented as two or more
different LFBs. Or else, it may add extra burden on
implementation to achieve interoperability.
3.2.2. LFB Class Groupings
The document defines groups of LFBs for typical router function
requirements:
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(1) A group of Ethernet processing LFBs are defined to abstract the
packet processing for Ethernet as the port media type. As the
most popular media type with rich processing features, Ethernet
media processing LFBs was a natural choice. Definitions for
processing of other port media types like POS or ATM may be
incorporated in the library in future version of the document or
in a future separate document. The following LFBs are defined
for Ethernet processing:
* EtherPHYCop (Section 5.1.1)
* EtherMACIn (Section 5.1.2)
* EtherClassifier (Section 5.1.3)
* EtherEncap (Section 5.1.4)
* EtherMACOut (Section 5.1.5)
(2) A group of LFBs are defined for IP packet validation process.
The following LFBs are defined for IP validation processing:
* IPv4Validator (Section 5.2.1)
* IPv6Validator (Section 5.2.2)
(3) A group of LFBs are defined to abstract IP forwarding process.
The following LFBs are defined for IP forwarding processing:
* IPv4UcastLPM (Section 5.3.1)
* IPv4NextHop (Section 5.3.2)
* IPv6UcastLPM (Section 5.3.3)
* IPv6NextHop (Section 5.3.4)
(4) A group of LFBs are defined to abstract the process for redirect
operation, i.e., data packet transmission between CE and FEs.
The following LFBs are defined for redirect processing:
* RedirectIn (Section 5.4.1)
* RedirectOut (Section 5.4.2)
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(5) A group of LFBs are defined for abstracting some general purpose
packet processing. These processing processes are usually
general to many processing locations in an FE LFB topology. The
following LFBs are defined for redirect processing:
* BasicMetadataDispatch (Section 5.5.1)
* GenericScheduler (Section 5.5.2)
3.2.3. Sample LFB Class Application
Although Section 7 will present use cases for LFBs defined in this
document, this section shows a sample LFB class application in
advance so that readers can get a quick overlook of the LFB classes
with the usage.
Figure 1 shows the typical LFB processing path for an IPv4 unicast
forwarding case with Ethernet media interfaces. To focus on the IP
forwarding function, some inputs or outputs of LFBs in the figure
that are not related to the function are ignored. Section 7.1 will
describe the figure in details.
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+-----+ +------+
| | | |
| |<---------------|Ether |<----------------------------+
| | |MACOut| |
| | | | |
|Ether| +------+ |
|PHY | |
|Cop | +---+ |
|#1 | +-----+ | |----->IPv6 Packets |
| | | | | | |
| | |Ether| | | IPv4 Packets |
| |->|MACIn|-->| |-+ +----+ |
+-----+ | | | | | | |---> Multicast Packets |
+-----+ +---+ | | | +-----+ +---+ |
Ether +->| |------->| | | | |
. Classifier| | |Unicast |IPv4 | | | |
. | | |Packets |Ucast|->| |--+ |
. | +----+ |LPM | | | | |
+---+ | IPv4 +-----+ +---+ | |
+-----+ | | | Validator IPv4 | |
| | | | | NextHop| |
+-----+ |Ether| | |-+ IPv4 Packets | |
| |->|MACIn|-->| | | |
| | | | | |----->IPv6 Packets | |
|Ether| +-----+ +---+ | |
|PHY | Ether +----+ | |
|Cop | Classifier | | +-------+ | |
|#n | +------+ | | |Ether | | |
| | | | | |<--|Encap |<-+ |
| | | |<------| | | | |
| |<---------------|Ether | ...| | +-------+ |
| | |MACOut| +---| | |
| | | | | +----+ |
+-----+ +------+ | BasicMetadataDispatch |
+-------------------------+
Figure 1: LFB use case for IPv4 forwarding
3.3. Document Structure
Base type definitions, including data types, packet frame types, and
metadata types are presented in advance for definitions of various
LFB classes. Section 4 (Base Types section) provides a description
on the base types used by this LFB library. To enable extensive use
of these base types by other LFB class definitions, the base type
definitions are provided as a separate library.
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Within every group of LFB classes, a set of LFBs are defined for
individual function purposes. Section 5 (LFB Class Descriptions
section) provides text descriptions on the individual LFBs. Note
that for a complete definition of an LFB, a text description as well
as a XML definition is required.
LFB classes are finally defined by XML with specifications and schema
defined in the ForCES FE model[RFC5812]. Section 6 (XML LFB
Definitions section) provides the complete XML definitions of the
base LFB classes library.
Section 7 provides several use cases on how some typical router
functions can be implemented using the base LFB library defined in
this document.
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4. Base Types
The FE model [RFC5812] has specified predefined (built-in) atomic
data-types as below:
char, uchar, int16, uint16, int32, uint32, int64, uint64, string[N],
string, byte[N], boolean, octetstring[N], float16, float32, float64.
Based on the atomic data types and with the use of type definition
elements in the FE model XML schema, new data types, packet frame
types, and metadata types can be defined.
To define a base LFB library for typical router functions, a set of
base data types, frame types, and metadata types should be defined.
This section provides a brief description of the base types and a
full XML definition of them as well.
The base type XML definitions are provided with a separate XML
library file named "BaseTypeLibrary". Users can refer to this
library by the statement:
4.1. Data Types
Data types defined in the base type library are categorized by types
of atomic, compound struct, and compound array.
4.1.1. Atomic
The following data types are defined as atomic data types and put in
the base type library:
Data Type Name Brief Description
-------------- -----------------
IPv4Addr IPv4 address
IPv6Addr IPv6 address
IEEEMAC IEEE MAC address
LANSpeedType Network speed values
DuplexType Duplex types
PortStatusValues The possible values of port status, used for
both administrative and operative status
VlanIDType The type of VLAN ID
VlanPriorityType The type of VLAN priority
SchdDisciplineType Scheduling discipline type
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4.1.2. Compound struct
The following compound struct types are defined in the base type
library:
Data Type Name Brief Description
-------------- -----------------
EtherDispatchEntryType Entry type for Ethernet dispatch table
VlanInputTableEntryType Entry type for VLAN input table
EncapTableEntryType Entry type for Ethernet encapsulation table
MACInStatsType Statistics type for EtherMACIn LFB
MACOutStatsType Statistics type for EtherMACOut LFB
EtherClassifyStatsType Entry type for statistics table in
EtherClassifier LFB
IPv4PrefixInfoType Entry type for IPv4 prefix table
IPv6PrefixInfoType Entry type for IPv6 prefix table
IPv4NextHopInfoType Entry type for IPv4 next hop table
IPv6NextHopInfoType Entry type for IPv6 next hop table
IPv4ValidatorStatsType Statistics type in IPv4validator LFB
IPv6ValidatorStatsType Statistics type in IPv6validator LFB
IPv4UcastLPMStatsType Statistics type in IPv4Unicast LFB
IPv6UcastLPMStatsType Statistics type in IPv6Unicast LFB
QueueStatsType Entry type for queue depth table
MetadataDispatchType Entry type for metadata dispatch table
4.1.3. Compound array
Compound array types are mostly created based on compound struct
types for LFB table components. The following compound array types
are defined in this base type library:
Data Type Name Brief Description
-------------- -----------------
EtherClassifyStatsTableType Type for Ethernet classifier statistics
information table
EtherDispatchTableType Type for Ethernet dispatch table
VlanInputTableType Type for VLAN input table
EncapTableType Type for Ethernet encapsulation table
IPv4PrefixTableType Type for IPv4 prefix table
IPv6PrefixTableType Type for IPv6 prefix table
IPv4NextHopTableType Type for IPv4 next hop table
IPv6NextHopTableType Type for IPv6 next hop table
MetadataDispatchTableType Type for Metadata dispatch table
QueueStatsTableType Type for Queue depth table
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4.2. Frame Types
According to FE model [RFC5812], frame types are used in LFB
definitions to define packet frame types both an LFB expects at its
input port and the LFB emits at its output port. The
element in the FE model is used to define a new frame type.
The following frame types are defined in the base type library:
Frame Name Brief Description
-------------- ----------------
EthernetII An Ethernet II frame
ARP An ARP packet
IPv4 An IPv4 packet
IPv6 An IPv6 packet
IPv4Unicast An IPv4 unicast packet
IPv4Multicast An IPv4 multicast packet
IPv6Unicast An IPv6 unicast packet
IPv6Multicast An IPv6 multicast packet
Arbitrary Any types of packet frames
4.3. MetaData Types
LFB Metadata is used to communicate per-packet state from one LFB to
another. The element in the FE model is used to define
a new metadata type.
The following metadata types are currently defined in the base type
library.
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Metadata Name Metadata ID Brief Description
------------ ---------- -------------
PHYPortID 1 The ingress physical port that the packet
arrived on
SrcMAC 2 Source MAC address of the packet
DstMAC 3 Destination MAC address of the packet
LogicalPortID 4 ID of a logical port for the packet
EtherType 5 The packet's Ethernet type
VlanID 6 The VLAN ID of the Ethernet packet
VlanPriority 7 The priority of the Ethernet packet
NexthopIPv4Addr 8 Nexthop IPv4 address the packet is sent to
NexthopIPv6Addr 9 Nexthop IPv6 address the packet is sent to
HopSelector 10 A search key the packet can use to look up
a nexthop table for next hop information
of the packet
ExceptionID 11 Indicating exception type of the packet
which is exceptional for some processing
ValidateErrorID 12 Indicating error type of the packet failed
some validation process
L3PortID 13 ID of L3 port
RedirectIndex 14 A metadata CE sends to RedirectIn LFB for
the associated packet to select output
port in the LFB group output "PktsOut"
MediaEncapInfoIndex 15 A search key the packet uses to look up a
media encapsulation table to select its
encapsulation media as well as followed
encapsulation LFB
4.4. XML for Base Type Library
EthernetAll
All kinds of Ethernet frame
EthernetII
An Ethernet II frame
ARP
An arp packet
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IPv4
An IPv4 packet
IPv6
An IPv6 packet
IPv4Unicast
An IPv4 unicast packet
IPv4Multicast
An IPv4 multicast packet
IPv6Unicast
An IPv6 unicast packet
IPv6Multicast
An IPv6 multicast packet
Arbitrary
Any types of packet frames
IPv4Addr
IPv4 address
byte[4]
IPv6Addr
IPv6 address
byte[16]
IEEEMAC
IEEE MAC address.
byte[6]
LANSpeedType
Network speed values
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uint32
LAN_SPEED_10M
10M Ethernet
LAN_SPEED_100M
100M Ethernet
LAN_SPEED_1G
1000M Ethernet
LAN_SPEED_10G
10G Ethernet
LAN_SPEED_AUTO
LAN speed auto
DuplexType
Duplex types
uint32
Auto
Auto negotitation.
Half-duplex
port negotitation half duplex
Full-duplex
port negotitation full duplex
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PortStatusValues
The possible values of port status, used for both
administrative and operative status.
uchar
Disabled
the port is operatively disabled.
UP
the port is up.
Down
The port is down.
MACInStatsType
Statistics type in EtherMACIn LFB.
NumPacketsReceived
The number of packets received.
uint64
NumPacketsDropped
The number of packets dropped.
uint64
MACOutStatsType
Statistics type in EtherMACOut LFB.
NumPacketsTransmitted
The number of packets transmitted.
uint64
NumPacketsDropped
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The number of packets dropped.
uint64
EtherDispatchEntryType
Entry type for Ethernet dispatch table in
EtherClassifier LFB.
LogicalPortID
Logical port ID.
uint32
EtherType
The EtherType value in the Ether head.
uint32
LFBOutputSelectIndex
LFB Group output port index to select
downstream LFB port. Some possibilities of downstream
LFB instances are:
a) IPv4Validator
b) IPv6Validator
c) RedirectOut
d) etc
Note: LFBOutputSelectIndex is the FromPortIndex for
the port group "ClassifyOut" in the table LFBTopology
(of FEObject LFB) as defined for the EtherClassifier
LFB.
uint32
EtherDispatchTableType
Type for Ethernet dispatch table.This table is used
in EtherClassifier LFB. Every Ethernet packet can be
dispatched to the LFB output group ports according to the
logical port ID.
EtherDispatchEntryType
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VlanIDType
The type of VLAN ID
uint16
VlanPriorityType
The type of VLAN priority.
uchar
VlanInputTableEntryType
Entry type for VLAN input table in EtherClassifier
LFB.
IncomingPortID
The incoming port ID.
uint32
VlanID
Vlan ID.
VlanIDType
LogicalPortID
logical port ID.
uint32
VlanInputTableType
Type for VLAN input table.This table is used
in EtherClassifier LFB. Every Ethernet packet can get a new
LogicalPortID according to the IncomingPortID and VlanID.
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VlanInputTableEntryType
EtherClassifyStatsType
Entry type for statistics table in EtherClassifier
LFB.
EtherType
The EtherType value
uint32
PacketsNum
Packets number
uint64
EtherClassifyStatsTableType
Type for Ethernet classifier statistics
information table in EtherClassifier LFB.
EtherClassifyStatsType
IPv4ValidatorStatsType
Statistics type in IPv4validator LFB.
badHeaderPkts
Number of bad header packets.
uint64
badTotalLengthPkts
Number of bad total length packets.
uint64
badTTLPkts
Number of bad TTL packets.
uint64
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badChecksumPkts
Number of bad checksum packets.
uint64
IPv6ValidatorStatsType
Statistics type in IPv6validator LFB.
badHeaderPkts
Number of bad header packets.
uint64
badTotalLengthPkts
Number of bad total length packets.
uint64
badHopLimitPkts
Number of bad Hop limit packets.
uint64
IPv4PrefixInfoType
Entry type for IPv4 prefix table.
IPv4Address
An IPv4 Address
IPv4Addr
Prefixlen
The prefix length
uchar
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HopSelector
HopSelector is the nexthop ID which points to
the nexthop table
uint32
ECMPFlag
An ECMP Flag for this route
boolean
False
This route does not have multiple
nexthops.
True
This route has multiple nexthops.
DefaultRouteFlag
A default route flag.
boolean
False
This is not a default route.
True
This route is a default route.
IPv4PrefixTableType
Type for IPv4 prefix table. This table is currently
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used in IPv4UcastLPM LFB. The LFB uses the destination IPv4
address of every input packet as search key to look up this
table in order extract a next hop selector.
IPv4PrefixInfoType
IPv4UcastLPMStatsType
Statistics type in IPv4Unicast LFB.
InRcvdPkts
The total number of input packets received.
uint64
FwdPkts
IPv4 packets forwarded by this LFB
uint64
NoRoutePkts
The number of IP datagrams discarded because
no route could be found.
uint64
IPv6PrefixInfoType
Entry type for IPv6 prefix table.
IPv6Address
An IPv6 Address
IPv6Addr
Prefixlen
The prefix length
uchar
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HopSelector
HopSelector is the nexthop ID which points
to the nexthop table
uint32
ECMPFlag
An ECMP Flag for this route
boolean
False
This route does not have multiple
nexthops.
True
This route has multiple nexthops.
DefaultRouteFlag
A Default Route Flag.
boolean
False
This is not a default route.
True
This route is a default route.
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IPv6PrefixTableType
Type for IPv6 prefix table.This table is currently
used in IPv6UcastLPM LFB. The LFB uses the destination IPv6
address of every input packet as search key to look up this
table in order extract a next hop selector.
IPv6PrefixInfoType
IPv6UcastLPMStatsType
Statistics type in IPv6Unicast LFB.
InRcvdPkts
The total number of input packets
received
uint64
FwdPkts
IPv6 packets forwarded by this LFB
uint64
NoRoutePkts
The number of IP datagrams discarded because
no route could be found.
uint64
IPv4NextHopInfoType
Entry type for IPv4 next hop table.
L3PortID
The ID of the Logical/physical Output Port
that we pass onto the downstream LFB instance. This
ID indicates what port to the neighbor is as defined
by L3.
uint32
MTU
Maximum Transmission Unit for out going port.
It is for desciding whether the packet need
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fragmentation
uint32
NextHopIPAddr
Next Hop IPv4 Address
IPv4Addr
MediaEncapInfoIndex
The index we pass onto the downstream LFB
instance. This index is used to lookup a table
(typically media encapsulatation related) further
downstream.
uint32
LFBOutputSelectIndex
LFB Group output port index to select
downstream LFB port. Some possibilities of downstream
LFB instances are:
a) EtherEncap
b) Other type of media LFB
c) A metadata Dispatcher
d) A redirect LFB
e) etc
Note: LFBOutputSelectIndex is the FromPortIndex for
the port group "SuccessOut" in the table LFBTopology
(of FEObject LFB) as defined for the IPv4NextHop LFB.
uint32
IPv4NextHopTableType
Type for IPv4 next hop table. This table is used
in IPv4NextHop LFB. The LFB uses metadata "HopSelector"
received to match the array index to get the next hop
information.
IPv4NextHopInfoType
IPv6NextHopInfoType
Entry type for IPv6 next hop table.
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L3PortID
The ID of the Logical/physical Output Port
that we pass onto the downstream LFB instance. This
ID indicates what port to the neighbor is as defined
by L3.
uint32
MTU
Maximum Transmission Unit for out going port.
It is for desciding whether the packet need
fragmentation.
uint32
NextHopIPAddr
Next Hop IPv6 Address
IPv6Addr
MediaEncapInfoIndex
The index we pass onto the downstream LFB
instance. This index is used to lookup a table
(typically media encapsulatation related) further
downstream.
uint32
LFBOutputSelectIndex
LFB Group output port index to select
downstream LFB port. Some possibilities of downstream
LFB instances are:
a) EtherEncap
b) Other type of media LFB
c) A metadata Dispatcher
d) A redirect LFB
e) etc
Note: LFBOutputSelectIndex is the FromPortIndex for
the port group "SuccessOut" in the table LFBTopology
(of FEObject LFB) as defined for the IPv6NextHop LFB.
uint32
IPv6NextHopTableType
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Type for IPv6 next hop table. This table is used
in IPv6NextHop LFB. The LFB uses metadata "HopSelector"
received to match the array index to get the next hop
information.
IPv6NextHopInfoType
EncapTableEntryType
Entry type for Ethernet encapsulation table in
EtherEncap LFB.
DstMac
Ethernet Mac of the Neighbor
IEEEMAC
SrcMac
Source MAC used in encapsulation
IEEEMAC
VlanID
VLAN ID.
VlanIDType
L2PortID
Output logical L2 port ID.
uint32
EncapTableType
Type for Ethernet encapsulation table. This
table is used in EtherEncap LFB. The LFB uses the metadata
"MediaEncapInfoIndex " received to get the encapsulation
information.
EncapTableEntryType
MetadataDispatchType
Entry type for Metadata dispatch table in
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BasicMetadataDispatch LFB.
MetadataValue
metadata value.
uint32
OutputIndex
group output port index.
uint32
MetadataDispatchTableType
Type for Metadata dispatch table. This table is used
in BasicMetadataDispatch LFB. The LFB uses MetadataValue to
get the LFB group output port index.
MetadataDispatchType
MetadataValue
SchdDisciplineType
Scheduling discipline type.
uint32
RR
Round Robin scheduler.
QueueStatsType
Entry type for queue statistics table in
GenericScheduler LFB.
QueueID
Queue ID
uint32
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QueueDepthInPackets
the Queue Depth when the depth units
are packets.
uint32
QueueDepthInBytes
the Queue Depth when the depth units
are bytes.
uint32
QueueStatsTableType
Type for Queue statistics table in GenericScheduler
LFB.
QueueDepthType
PHYPortID
The physical port ID that a packet has entered.
1
uint32
SrcMAC
Source MAC address of the packet.
2
IEEEMAC
DstMAC
Destination MAC address of the packet.
3
IEEEMAC
LogicalPortID
ID of a logical port for the packet.
4
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uint32
EtherType
Indicating the Ethernet type of the Ethernet packet.
5
uint32
VlanID
The Vlan ID of the Ethernet packet.
6
VlanIDType
VlanPriority
The priority of the Ethernet packet.
7
VlanPriorityType
NexthopIPv4Addr
Nexthop IPv4 address the packet is sent to.
8
IPv4Addr
NexthopIPv6Addr
Nexthop IPv6 address the packet is sent to.
9
IPv6Addr
HopSelector
A search key the packet can use to look up a nexthop
table for next hop information of the packet.
10
uint32
ExceptionID
Indicating exception type of the packet which is
exceptional for some processing.
11
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uint32
AnyUnrecognizedExceptionCase
any unrecognized exception case.
ClassifyNoMatching
There is no matching when classifying the
packet in EtherClassifier LFB.
MediaEncapInfoIndexInvalid
The MediaEncapInfoIndex value of the
packet is invalid and can not be allocated in the
EncapTable.
EncapTableLookupFailed
The packet failed lookup of the EncapTable
table even though the MediaEncapInfoIndex is valid.
BadTTL
Packet with expired TTL.
IPv4HeaderLengthMismatch
Packet with header length more than 5
words.
RouterAlertOptions
Packet IP head include Router Alert
options.
IPv6HopLimitZero
Packet with Hop Limit zero
IPv6NextHeaderHBH
Packet with next header set to Hop-by-Hop
SrcAddressExecption
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Packet with exceptional source address.
DstAddressExecption
Packet with exceptional destination
address
LPMLookupFailed
The packet failed the LPM lookup of the
prefix table.
HopSelectorInvalid
The HopSelector for the packet is invalid.
NextHopLookupFailed
The packet failed lookup of the NextHop
table even though the HopSelector is valid.
FragRequired
The MTU for outgoing interface is less
than the packet size.
MetadataNoMatching
There is no matching when looking up the
metadata dispatch table.
ValidateErrorID
Indicating error type of the packet failed some
validation process.
12
uint32
AnyUnrecognizedValidateErrorCase
Any unrecognized validate error case.
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InvalidIPv4PacketSize
Packet size reported is less than 20
bytes.
NotIPv4Packet
Packet is not IP version 4.
InvalidIPv4HeaderLengthSize
Packet with header length less than
5 words.
InvalidIPv4LengthFieldSize
Packet with total length field less than
20 bytes.
InvalidIPv4Checksum
Packet with invalid checksum.
InvalidIPv4SrcAddr
Packet with invalid source address.
InvalidIPv4DstAddr
Packet with source address 0.
InvalidIPv6PacketSize
Packet size reported is less than 40
bytes.
NotIPv6Packet
Packet is not IP version 6.
InvalidIPv6SrcAddr
Packet with invalid source address.
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InvalidIPv6DstAddr
Packet with invalid destination address.
L3PortID
ID of L3 port. See the definition in
IPv4NextHopInfoType.
13
uint32
RedirectIndex
metadata CE sends to RedirectIn LFB for the
associated packet to select output port in the LFB group
output "PktsOut".
14
uint32
MediaEncapInfoIndex
A search key the packet uses to look up a media
encapsulation table to select its encapsulation media as
well as followed encapsulation LFB.
15
uint32
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5. LFB Class Description
According to ForCES specifications, LFB (Logical Function Block) is a
well defined, logically separable functional block that resides in an
FE, and is a functionally accurate abstraction of the FE's processing
capabilities. An LFB Class (or type) is a template that represents a
fine-grained, logically separable aspect of FE processing. Most LFBs
are related to packet processing in the data path. LFB classes are
the basic building blocks of the FE model. Note that [RFC5810] has
already defined an 'FE Protocol LFB' which is a logical entity in
each FE to control the ForCES protocol. [RFC5812] has already
defined an 'FE Object LFB'. Information like the FE Name, FE ID, FE
State, LFB Topology in the FE are represented in this LFB.
As specified in Section 3.1, this document focuses on the base LFB
library for implementing typical router functions, especially for IP
forwarding functions. As a result, LFB classes in the library are
all base LFBs to implement router forwarding.
In this section, the terms "upstream LFB" and "downstream LFB" are
used. These are used relative to an LFB to an LFB that is being
described. An "upstream LFB" is one whose output ports are connected
to input ports of the LFB under consideration such that output
(typically packets with metadata) can be sent from the "upstream LFB"
to the LFB under consideration. Similarly, a "downstream LFB" whose
input ports are connected to output ports of the LFB under
consideration such that the LFB under consideration can send
information to the "downstream LFB". Note that in some rare
topologies, an LFB may be both upstream and downstream relative to
another LFB.
Also note that, as a default provision of [RFC5812], in FE model, all
metadata produced by upstream LFBs will pass through all downstream
LFBs by default without being specified by input port or output port.
Only those metadata that will be used (consumed) by an LFB will be
explicitly marked in input of the LFB as expected metadata. For
instance, in downstream LFBs of a physical layer LFB, even there is
no specific metadata expected, metadata like PHYPortID produced by
the physical layer LFB will always pass through all downstream LFBs
regardless of whether the metadata has been expected by the LFBs or
not.
5.1. Ethernet Processing LFBs
As the most popular physical and data link layer protocols, Ethernet
is widely deployed. It becomes a basic requirement for a router to
be able to process various Ethernet data packets.
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Note that there exist different versions of Ethernet formats, like
Ethernet V2, 802.3 RAW, IEEE 802.3/802.2, IEEE 802.3/802.2 SNAP.
There also exist varieties of LAN techniques based on Ethernet, like
various VLANs, MACinMAC, etc. Ethernet processing LFBs defined here
are intended to be able to cope with all these variations of Ethernet
technology.
There are also various types of Ethernet physical interface media.
Among them, copper and fiber media may be the most popular ones. As
a base LFB definition and a starting point, the document only defines
an Ethernet physical LFB with copper media. For other media
interfaces, specific LFBs may be defined in the future versions of
the library.
5.1.1. EtherPHYCop
EtherPHYCop LFB abstracts an Ethernet interface physical layer with
media limited to copper.
5.1.1.1. Data Handling
This LFB is the interface to the Ethernet physical media. The LFB
handles ethernet frames coming in from or going out of the FE.
Ethernet frames sent and received cover all packets encapsulated with
different versions of Ethernet protocols, like Ethernet V2, 802.3
RAW, IEEE 802.3/802.2,IEEE 802.3/802.2 SNAP, including packets
encapsulated with varieties of LAN techniques based on Ethernet, like
various VLANs, MACinMAC, etc. Therefore in the XML an EthernetAll
frame type has been introduced.
Ethernet frames are received from the physical media port and passed
downstream to LFBs such as EtherMACIn via a singleton output known as
"EtherPHYOut". A 'PHYPortID' metadata, to indicate which physical
port the frame came into from the external world, is passed along
with the frame.
Ethernet packets are received by this LFB from upstream LFBs such as
EtherMacOut LFBs via the singleton input known as "EtherPHYIn" before
being sent out onto the external world.
5.1.1.2. Components
The AdminStatus component is defined for CE to administratively
manage the status of the LFB. The CE may administratively startup or
shutdown the LFB by changing the value of AdminStatus. The default
value is set to 'Down'.
An OperStatus component captures the physical port operational
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status. A PHYPortStatusChanged event is defined so the LFB can
report to the CE whenever there is an operational status change of
the physical port.
The PHYPortID component is a unique identification for a physical
port. It is defined as 'read-only' by CE. Its value is enumerated
by FE. The component will be used to produce a 'PHYPortID' metadata
at the LFB output and to associate it to every Ethernet packet this
LFB receives. The metadata will be handed to downstream LFBs for
them to use the PHYPortID.
A group of components are defined for link speed management. The
AdminLinkSpeed is for CE to configure link speed for the port and the
OperLinkSpeed is for CE to query the actual link speed in operation.
The default value for the AdminLinkSpeed is set to auto-negotiation
mode.
A group of components are defined for duplex mode management. The
AdminDuplexMode is for CE to configure proper duplex mode for the
port and the OperDuplexMode is for CE to query the actual duplex mode
in operation. The default value for the AdminDuplexMode is set to
auto-negotiation mode.
A CarrierStatus component captures the status of the carrier and
specifies whether the port link is operationally up. The default
value for the CarrierStatus is 'false'.
5.1.1.3. Capabilities
The capability information for this LFB includes the link speeds that
are supported by the FE (SupportedLinkSpeed) as well as the supported
duplex modes (SupportedDuplexMode).
5.1.1.4. Events
Several events are generated. There is an event for changes in the
status of the physical port (PhyPortStatusChanged). Such an event
will notify that the physical port status has been changed and the
report will include the new status of the physical port.
Another event captures changes in the operational link speed
(LinkSpeedChanged). Such an event will notify the CE that the
operational speed has been changed and the report will include the
new negotiated operational speed.
A final event captures changes in the duplex mode
(DuplexModeChanged). Such an event will notify the CE that the
duplex mode has been changed and the report will include the new
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negotiated duplex mode.
5.1.2. EtherMACIn
EtherMACIn LFB abstracts an Ethernet port at MAC data link layer.
This LFB describes Ethernet processing functions like MAC address
locality check, deciding if the Ethernet packets should be bridged,
providing Ethernet layer flow control, etc.
5.1.2.1. Data Handling
The LFB is expected to receive all types of Ethernet packets, via a
singleton input known as "EtherPktsIn", which are usually output from
some Ethernet physical layer LFB, like an EtherPHYCop LFB, alongside
with a metadata indicating the physical port ID that the packet
arrived on.
The LFB is defined with two separate singleton outputs. All Output
packets are emitted in the original ethernet format received at the
physical port, unchanged, and cover all types of ethernet types.
The first singleton output is known as "NormalPathOut". It usually
outputs Ethernet packets to some LFB like an EtherClassifier LFB for
further L3 forwarding process alongside with a PHYPortID metadata
indicating which physical port the packet came from.
The second singleton output is known as "L2BridgingPathOut".
Although the LFB library this document defines is basically to meet
typical router functions, it will attempt to be forward compatible
with future router functions. The "L2BridgingPathOut" is defined to
meet the requirement that L2 bridging functions may be optionally
supported simultaneously with L3 processing and some L2 bridging LFBs
that may be defined in the future. If the FE supports L2 bridging,
the CE can enable or disable it by means of a "L2BridgingPathEnable"
component in the FE. If it is enabled, by also instantiating some L2
bridging LFB instances following the L2BridgingPathOut, FEs are
expected to fulfill L2 bridging functions. L2BridgingPathOut will
output packets exactly the same as that in the NormalPathOut output.
This LFB can be set to work in a Promiscuous Mode, allowing all
packets to pass through the LFB without being dropped. Otherwise, a
locality check will be performed based on the local MAC addresses.
All packets that do not pass through the locality check will be
dropped.
This LFB participates in Ethernet flow control in cooperation with
EtherMACOut LFB. This document does not go into the details of how
this is implemented; the reader may refer to some relevant
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references. This document also does not describe how the buffers
which induce the flow control messages behave - it is assumed that
such artifacts exist and describing them is out of scope in this
document.
5.1.2.2. Components
The AdminStatus component is defined for the CE to administratively
manage the status of the LFB. The CE may administratively startup or
shutdown the LFB by changing the value of AdminStatus. The default
value is set to 'Down'.
The LocalMACAddresses component specifies the local MAC addresses
based on which locality checks will be made. This component is an
array of MAC addresses, and of 'read-write' access permission.
An L2BridgingPathEnable component captures whether the LFB is set to
work as a L2 bridge. An FE that does not support bridging will
internally set this flag to false, and additionally set the flag
property as read-only. The default value for is 'false'.
The PromiscuousMode component specifies whether the LFB is set to
work as in a promiscuous mode. The default value for is 'false'.
The TxFlowControl component defines whether the LFB is performing
flow control on sending packets. The default value for is 'false'.
The RxFlowControl component defines whether the LFB is performing
flow control on receiving packets. The default value for is 'false'.
A struct component, MACInStats, defines a set of statistics for this
LFB, including the number of received packets and the number of
dropped packets.
5.1.2.3. Capabilities
This LFB does not have a list of capabilities.
5.1.2.4. Events
This LFB does not have any events specified.
5.1.3. EtherClassifier
EtherClassifier LFB abstracts the process to decapsulate Ethernet
packets and then classify them.
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5.1.3.1. Data Handling
This LFB describes the process of decapsulating Ethernet packets and
classifying them into various network layer data packets according to
information included in the Ethernet packets headers.
The LFB is expected to receive all types of Ethernet packets, via a
singleton input known as "EtherPktsIn", which are usually output from
an upstream LFB like EtherMACIn LFB. This input is also capable of
multiplexing to allow for multiple upstream LFBs being connected.
For instance, when L2 bridging function is enabled in EtherMACIn LFB,
some L2 bridging LFBs may be applied. In this case, some Ethernet
packets after L2 processing may have to be input to EtherClassifier
LFB for classification, while simultaneously packets directly output
from EtherMACIn may also need to input to this LFB. This input is
capable of handling such a case. Usually, all expected Ethernet
Packets will be associated with a PHYPortID metadata, indicating the
physical port the packet comes from. In some cases, for instance,
like in a MACinMAC case, a LogicalPortID metadata may be expected to
associate with the Ethernet packet to further indicate which logical
port the Ethernet packet belongs to. Note that PHYPortID metadata is
always expected while LogicalPortID metadata is optionally expected.
Two output LFB ports are defined.
The first output is a group output port known as "ClassifyOut".
Types of network layer protocol packets are output to instances of
the port group. Because there may be various types of protocol
packets at the output ports, the produced output frame is defined as
arbitrary for the purpose of wide extensibility in the future.
Metadata to be carried along with the packet data is produced at this
LFB for consumption by downstream LFBs. The metadata passed
downstream includes PHYPortID, as well as information on Ethernet
type, source MAC address, destination MAC address and the logical
port ID. .If the original packet is a VLAN packet and contains a VLAN
ID and a VLAN priority value, then the VLAN ID and the VLAN priority
value are also carried downstream as metadata. As a result, the VLAN
ID and priority metadata are defined with the availability of
"conditional".
The second output is a singleton output port known as "ExceptionOut",
which will output packets for which the data processing failed, along
with an additional ExceptionID metadata to indicate what caused the
exception. Currently defined exception types include:
o There is no matching when classifying the packet.
Usually the exception out port may point to no where, indicating
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packets with exceptions are dropped, while in some cases, the output
may be pointed to the path to the CE for further processing,
depending on individual implementations.
5.1.3.2. Components
An EtherDispatchTable array component is defined in the LFB to
dispatch every Ethernet packet to the output group according to the
logical port ID assigned by the VlanInputTable to the packet and the
Ethernet type in the Ethernet packet header. Each row of the array
is a struct containing a Logical Port ID, an EtherType and an Output
Index. With the CE configuring the dispatch table, the LFB can be
expected to classify various network layer protocol type packets and
output them at different output ports. It is expected that the LFB
classify packets according to protocols like IPv4, IPv6, MPLS, ARP,
ND, etc.
A VlanInputTable array component is defined in the LFB to classify
VLAN Ethernet packets. Each row of the array is a struct containing
an Incoming Port ID, a VLAN ID and a Logical Port ID. According to
IEEE VLAN specifications, all Ethernet packets can be recognized as
VLAN types by defining that if there is no VLAN encapsulation in a
packet, a case with VLAN tag 0 is considered. Every input packet is
assigned with a new LogicalPortID according to the packet incoming
port ID and the VLAN ID. A packet incoming port ID is defined as a
logical port ID if a logical port ID is associated with the packet,
or a physical port ID if no logical port ID associated. The VLAN ID
is exactly the VLAN ID in the packet if it is a VLAN packet, or 0 if
it is not. Note that a logical port ID of a packet may be rewritten
with a new one by the VlanInputTable processing.
Note that the logical port ID and physical port ID mentioned above
are all originally configured by CE, and are globally effective
within a ForCES NE (Network Element). To distinguish a physical port
ID from a logical port ID in the incoming port ID field of the
VlanInputTable, physical port ID and logical port ID must be assigned
with separate number spaces.
An array component, EtherClassifyStats, defines a set of statistics
for this LFB, measuring the number of packets per EtherType. Each
row of the array is a struct containing an EtherType and a Packet
number.
5.1.3.3. Capabilities
This LFB does not have a list of capabilities.
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5.1.3.4. Events
This LFB has no events specified.
5.1.4. EtherEncap
The EtherEncap LFB abstracts the process to replace or attach
appropriate Ethernet headers to the packet.
5.1.4.1. Data Handling
This LFB abstracts the process of encapsulating Ethernet headers onto
received packets. The encapsulation is based on passed metadata.
The LFB is expected to receive IPv4 and IPv6 packets, via a singleton
input port known as "EncapIn" which may be connected to an upstream
LFB like an IPv4NextHop, an IPv6NextHop, BasicMetadataDispatch, or
any LFB which requires to output packets for Ethernet encapsulation.
The LFB always expects from upstream LFBs the MediaEncapInfoIndex
metadata which is used as a search key to lookup the Encapsulation
Table. An input packet may also optionally receive a VLAN priority
metadata, indicating that the packet is originally with a priority
value. The priority value will be loaded back to the packet when
encapsulating. The optional VLAN priority metadata is defined with a
default value 0.
Two singleton output LFB ports are defined.
The first singleton output known as "SuccessOut". Upon a successful
table lookup, the destination and source MAC addresses, and the
logical media port (L2PortID) are found in the matching table entry.
The CE may set the VlanID in case VLANs are used. By default the
table entry for VlanID of 0 is used as per IEEE rules. Whatever the
value of VlanID is, if the input metadata VlanPriority is non-zero,
the packet will have a VLAN tag. If the VlanPriority and the VlanID
are all zero, there is no VLAN tag to this packet. After replacing
or attaching the appropriate Ethernet headers to the packet is
complete, the packet is passed out on the "SuccessOut" LFB port to a
downstream LFB instance alongside with the L2PortID.
The second singleton output known as "ExceptionOut", which will
output packets for which the table lookup fails, along with an
additional ExceptionID metadata. Currently defined exception types
only include the following case:
o The MediaEncapInfoIndex value of the packet is invalid and can not
be allocated in the EncapTable.
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o The packet failed lookup of the EncapTable table even though the
MediaEncapInfoIndex is valid.
The upstream LFB may be programmed by the CE to pass along a
MediaEncapInfoIndex that does not exist in the EncapTable. That is
to allow for resolution of the L2 headers, if needed, to be made at
the L2 encapsulation level in this case (Ethernet) via ARP, or ND (or
other methods depending on the link layer technology) when a table
miss occurs.
For neighbor L2 header resolution(table miss exception), the
processing LFB may pass this packet to the CE via the redirect LFB or
FE software or another LFB instance for further resolution. In such
a case the metadata NexthopIPv4Addr or NexthopIPv6Addr generated by
Nexthop LFB is also passed to the exception handling. Such an IP
address could be used to do activities such as ARP or ND by the
handler it is passed to.
The result of the L2 resolution is to update the EncapTable as well
as the Nexthop LFB so subsequent packets do not fail EncapTable
lookup. The EtherEncap LFB does not make any assumptions of how the
EncapTable is updated by the CE (or whether ARP/ND is used
dynamically or static maps exist).
Downstream LFB instances could be either an EtherMACOut type or a
BasicMetadataDispatch type. If the final packet L2 processing is
possible to be on per-media-port basis or resides on a different FE
or in cases where L2 header resolution is needed, then the model
makes sense to use a BasicMetadataDispatch LFB to fanout to different
LFB instances. If there is a direct egress port point, then the
model makes sense to have a downstream LFB instance being an
EtherMACOut.
5.1.4.2. Components
This LFB has only one component named EncapTable which is defined as
an array. Each row of the array is a struct containing the
destination MAC address, the source MAC address, the VLAN ID with a
default value of zero and the output logical L2 port ID.
5.1.4.3. Capabilities
This LFB does not have a list of capabilities.
5.1.4.4. Events
This LFB does not have any events specified.
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5.1.5. EtherMACOut
EtherMACOut LFB abstracts an Ethernet port at MAC data link layer.
This LFB describes Ethernet packet output process. Ethernet output
functions are closely related to Ethernet input functions, therefore
many components defined in this LFB are as aliases of EtherMACIn LFB
components.
5.1.5.1. Data Handling
The LFB is expected to receive all types of Ethernet packets, via a
singleton input known as "EtherPktsIn", which are usually output from
an Ethernet encapsulation LFB, alongside with a metadata indicating
the physical port ID that the packet will go through.
The LFB is defined with a singleton output. All Output packets are
in Ethernet format, possibly with various Ethernet types, alongside
with a metadata indicating the physical port ID the packet is to go
through. This output links to a downstream LFB that is usually an
Ethernet physical LFB like EtherPHYcop LFB.
This LFB participates in Ethernet flow control in cooperation with
EtherMACIn LFB. This document does not go into the details of how
this is implemented; the reader may refer to some relevant
references. This document also does not describe how the buffers
which induce the flow control messages behave - it is assumed that
such artifacts exist and describing them is out of scope in this
document.
Note that as a base definition, functions like multiple virtual MAC
layers are not supported in this LFB version. It may be supported in
the future by defining a subclass or a new version of this LFB.
5.1.5.2. Components
The AdminStatus component is defined for CE to administratively
manage the status of the LFB. The CE may administratively startup or
shutdown the LFB by changing the value of AdminStatus. The default
value is set to 'Down'. Note that this component is defined as an
alias of the AdminStatus component in the EtherMACIn LFB. This
infers that an EtherMACOut LFB usually coexists with an EtherMACIn
LFB, both of which share the same administrative status management by
CE. Alias properties as defined in the ForCES FE model [RFC5812]
will be used by CE to declare the target component this alias refers,
which include the target LFB class and instance IDs as well as the
path to the target component.
The MTU component defines the maximum transmission unit.
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The TxFlowControl component defines whether the LFB is performing
flow control on sending packets. The default value for is 'false'.
Note that this component is defined as an alias of TxFlowControl
component in the EtherMACIn LFB.
The RxFlowControl component defines whether the LFB is performing
flow control on receiving packets. The default value for is 'false'.
Note that this component is defined as an alias of RxFlowControl
component in the EtherMACIn LFB.
A struct component, MACOutStats, defines a set of statistics for this
LFB, including the number of transmitted packets and the number of
dropped packets.
5.1.5.3. Capabilities
This LFB does not have a list of capabilities.
5.1.5.4. Events
This LFB does not have any events specified.
5.2. IP Packet Validation LFBs
The LFBs are defined to abstract IP packet validation process. An
IPv4Validator LFB is specifically for IPv4 protocol validation and an
IPv6Validator LFB for IPv6.
5.2.1. IPv4Validator
The IPv4Validator LFB performs IPv4 packets validation according to
[RFC5812].
5.2.1.1. Data Handling
This LFB performs IPv4 validation according to [RFC5812]. The IPv4
packet will be output to the corresponding LFB port the indication
whether the packet is unicast, multicast or whether an exception has
occurred or the validation failed.
This LFB always expects, as input, packets which have been indicated
as IPv4 packets by an upstream LFB, like an EtherClassifier LFB.
There is no specific metadata expected by the input of the LFB.
Four output LFB ports are defined.
All validated IPv4 unicast packets will be output at the singleton
port known as "IPv4UnicastOut". All validated IPv4 multicast packets
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will be output at the singleton port known as "IPv4MulticastOut"
port.
A singleton port known as "ExceptionOut" is defined to output packets
which have been validated as exception packets. An exception ID
metadata is produced to indicate what has caused the exception. An
exception case is the case when a packet needs further processing
before being normally forwarded. Currently defined exception types
include:
o Packet with expired TTL
o Packet with header length more than 5 words
o Packet IP head including Router Alert options
o Packet with exceptional source address
o Packet with exceptional destination address
Note that although TTL is checked in this LFB for validity,
operations like TTL decrement are made by the downstream forwarding
LFB.
The final singleton port known as "FailOut" is defined for all
packets which have errors and failed the validation process. An
error case is the case when a packet is unable to be further
processed nor forwarded except being dropped. An error ID is
associated a packet to indicate the failure reason. Currently
defined failure reasons include:
o Packet with size reported less than 20 bytes
o Packet with version is not IPv4
o Packet with header length less than 5 words
o Packet with total length field less than 20 bytes
o Packet with invalid checksum
o Packet with invalid source address
o Packet with invalid destination address
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5.2.1.2. Components
This LFB has only one struct component, the
IPv4ValidatorStatisticsType, which defines a set of statistics for
validation process, including the number of bad header packets, the
number of bad total length packets, the number of bad TTL packets,
and the number of bad checksum packets.
5.2.1.3. Capabilities
This LFB does not have a list of capabilities
5.2.1.4. Events
This LFB does not have any events specified.
5.2.2. IPv6Validator
The IPv6Validator LFB performs IPv6 packets validation according to
[RFC2460].
5.2.2.1. Data Handling
This LFB performs IPv6 validation according to [RFC2460]. Then the
IPv6 packet will be output to the corresponding port regarding of the
validation result, whether the packet is a unicast or a multicast
one, an exception has occurred or the validation failed.
This LFB always expects, as input, packets which have been indicated
as IPv6 packets by an upstream LFB, like an EtherClassifier LFB.
There is no specific metadata expected by the input of the LFB.
Similar to the IPv4validator LFB, IPv6Validator LFB has also defined
four output ports to emit packets with various validation results.
All validated IPv6 unicast packets will be output at the singleton
port known as "IPv6UnicastOut". All validated IPv6 multicast packets
will be output at the singleton port known as "IPv6MulticastOut"
port. There is no metadata produced at this LFB.
A singleton port known as "ExceptionOut" is defined to output packets
which have been validated as exception packets. An exception case is
the case when a packet needs further processing before being normally
forwarded. An exception ID metadata is produced to indicate what
caused the exception. Currently defined exception types include:
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o Packet with hop limit to zero
o Packet with next header set to Hop-by-Hop
o Packet with exceptional source address
o Packet with exceptional destination address
The final singleton port known as "FailOut" is defined for all
packets which have errors and failed the validation process. An
error case is the case when a packet is unable to be further
processed nor forwarded except being dropped. A validate error ID is
associated to every failed packet to indicate the reason. Currently
defined reasons include:
o Packet with size reported less than 40 bytes
o Packet with not IPv6 version
o Packet with invalid source address
o Packet with invalid destination address
Note that in the base type library, definitions for exception ID and
validate error ID metadata are applied to both IPv4Validator and
IPv6Validator LFBs, i.e., the two LFBs share the same medadata
definition, with different ID assignment inside.
5.2.2.2. Components
This LFB has only one struct component, the
IPv6ValidatorStatisticsType, which defines a set of statistics for
validation process, including the number of bad header packets, the
number of bad total length packets, and the number of bad hop limit
packets.
5.2.2.3. Capabilities
This LFB does not have a list of capabilities
5.2.2.4. Events
This LFB does not have any events specified.
5.3. IP Forwarding LFBs
IP Forwarding LFBs are specifically defined to abstract the IP
forwarding processes. As definitions for a base LFB library, this
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document restricts its LFB definition scope only to IP unicast
forwarding. IP multicast may be defined in future documents.
A typical IP unicast forwarding job is usually realized by looking up
the forwarding information table to find next hop information, and
then based on the next hop information, forwarding packets to
specific physical output ports. It usually takes two steps to do so,
firstly to look up a forwarding information table by means of Longest
Prefix Matching(LPM) rule to find a next hop index, then to use the
index as a search key to look up a next hop information table to find
enough information to submit packets to output ports. This document
abstracts the forwarding processes mainly based on the two steps
model. However, there actually exists other models, like one which
may only have a forwarding information base that have conjoined next
hop information together with forwarding information. In this case,
if ForCES technology is to be applied, some translation work will
have to be done in the FE to translate attributes defined by this
document into attributes related to the implementation.
Based on the IP forwarding abstraction, two kind of typical IP
unicast forwarding LFBs are defined, Unicast LPM lookup LFB and next
hop application LFB. They are further distinguished by IPv4 and IPv6
protocols.
5.3.1. IPv4UcastLPM
The IPv4UcastLPM LFB abstracts the IPv4 unicast Longest Prefix Match
(LPM) process.
This LFB also provides facilities to support users to implement
equal-cost multi-path routing (ECMP) or reverse path forwarding
(RPF). However, this LFB itself does not provide ECMP or RPF. To
fully implement ECMP or RPF, additional specific LFBs, like a
specific ECMP LFB or an RPF LFB, will have to be defined. This work
may be done in the future version of the document.
5.3.1.1. Data Handling
This LFB performs the IPv4 unicast LPM table looking up. It always
expects as input IPv4 unicast packets from one singleton input known
as "PktsIn". Then the LFB uses the destination IPv4 address of every
packet as search key to look up the IPv4 prefix table and generate a
hop selector as the matching result. The hop selector is passed as
packet metadata to downstream LFBs, and will usually be used there as
a search index to find more next hop information.
Three singleton output LFB ports are defined.
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The first singleton output known as "NormalOut" outputs IPv4 unicast
packets that succeed the LPM lookup and (got a hop selector). The
hop selector is associated with the packet as a metadata. Downstream
from the LPM LFB is usually a next hop application LFB, like an
IPv4NextHop LFB.
The second singleton output known as "ECMPOut" is defined to provide
support for users wishing to implement ECMP.
An ECMP flag is defined in the LPM table to enable the LFB to support
ECMP. When a table entry is created with the flag set true, it
indicates this table entry is for ECMP only. A packet, which has
passed through this prefix lookup, will always output from "ECMPOut"
output port, with the hop selector being its lookup result. The
output will usually directly go to a downstream ECMP processing LFB,
where the hop selector can usually further generate optimized one or
multiple next hop routes by use of ECMP algorithms.
A default route flag is defined in the LPM table to enable the LFB to
support a default route as well as loose RPF. When this flag is set
true, the table entry is identified a default route which also
implies that the route is forbidden for RPF. If a user wants to
implement RPF on FE, a specific RPF LFB will have to be defined. In
such RPF LFB, a component can be defined as an alias of the prefix
table component of this LFB as described below.
The final singleton output is known as "ExceptionOut" and is defined
to allow exception packets to output here, along with an ExceptionID
metadata to indicate what caused the exception. Currently defined
exception types include:
o The packet failed the LPM lookup of the prefix table.
The upstream LFB of this LFB is usually IPv4Validator LFB. If RPF is
to be adopted, the upstream can be an RPF LFB, when defined.
The downstream LFB is usually IPv4NextHop LFB. If ECMP is adopted,
the downstream can be an ECMP LFB, when defined.
5.3.1.2. Components
This LFB has two components.
The IPv4PrefixTable component is defined as an array component of the
LFB. Each row of the array contains an IPv4 address, a Prefix
length, a Hop Selector, an ECMP flag and a Default Route flag. The
LFB uses the destination IPv4 address of every input packet as search
key to look up this table in order extract a next hop selector. The
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ECMP flag is for the LFB to support ECMP. The default route flag is
for the LFB to support a default route and for loose RPF.
The IPv4UcastLPMStats component is a struct component which collects
statistics information, including the total number of input packets
received, the IPv4 packets forwarded by this LFB and the number of IP
datagrams discarded due to no route found.
5.3.1.3. Capabilities
This LFB does not have a list of capabilities
5.3.1.4. Events
This LFB does not have any events specified.
5.3.2. IPv4NextHop
This LFB abstracts the process of selecting ipv4 next hop action.
5.3.2.1. Data Handling
The LFB abstracts the process of next hop information application to
IPv4 packets. It receives an IPv4 packet with an associated next hop
identifier (HopSelector), and uses the identifier as a table index to
look up a next hop table to find an appropriate LFB output port.
The LFB is expected to receive unicast IPv4 packets, via a singleton
input known as "PcktsIn" along with a HopSelector metadata which is
used as a table index to lookup the NextHop table. The data
processing involves the forwarding TTL decrement and IP checksum
recalculation.
Two output LFB ports are defined.
The first output is a group output port known as "SuccessOut". On
successful data processing the packet is sent out an LFB-port from
within the LFB port group as selected by the LFBOutputSelectIndex
value of the matched table entry. The packet is sent to a downstream
LFB alongside with the L3PortID and MediaEncapInfoIndex metadata.
The second output is a singleton output port known as "ExceptionOut",
which will output packets for which the data processing failed, along
with an additional ExceptionID metadata to indicate what caused the
exception. Currently defined exception types include:
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o The HopSelector for the packet is invalid.
o The packet failed lookup of the NextHop table even though the
HopSelector is valid.
o The MTU for outgoing interface is less than the packet size.
Downstream LFB instances could be either a BasicMetadataDispatch type
(Section 5.5.1), used to fanout to different LFB instances or a media
encapsulation related type, such as an EtherEncap type or a
RedirectOut type(Section 5.4.2). For example, if there are Ethernet
and other tunnel Encapsulation, then a BasicMetadataDispatch LFB can
use the L3PortID metadata (Section 5.3.2.2) to dispatch packets to
different Encapsulator.
5.3.2.2. Components
This LFB has only one component named IPv4NextHopTable which is
defined as an array. The HopSelector received is used to match the
array index of IPv4NextHopTable to find out a row of the table as the
next hop information result. Each row of the array is a struct
containing:
o The L3PortID, which is the ID of the Logical Output Port that is
passed onto the downstream LFB instance. This ID indicates what
port to the neighbor is as defined by L3. Usually this ID is used
for the NextHop LFB to distinguish packets that need different L2
encapsulating. For instance, some packets may require general
Ethernet encapsulation while others may require various types of
tunnel encapsulations. In such case, different L3PortIDs are
assigned to the packets and are as metadata passed to downstream
LFB. A BasicMetadataDispatch LFB(Section 5.5.1) may have to be
applied as the downstream LFB so as to dispatch packets to
different encapsulation LFB insatnces according to the L3PortIDs.
o MTU, the Maximum Transmission Unit for the outgoing port.
o NextHopIPAddr, the IPv4 next hop Address.
o MediaEncapInfoIndex, the index we pass onto the downstream
encapsulation LFB instance and that is used there as a search key
to lookup a table (typically media encapsulation related) for
further encapsulation information. Note that an encapsulation LFB
instance may not directly follow the NextHop LFB, but the index is
passed as a metadata associated, as such an encapsulation LFB
instance even further downstream to the NextHop LFB can still use
the index. In some cases, depending on implementation, the CE may
set the MediaEncapInfoIndex passed downstream to a value that will
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fail lookup when it gets to a target encapsulation LFB; such a
lookup failure at that point is an indication that further
resolution is needed. For an example of this approach refer to
Section 7.2 which talks about ARP and mentions this approach.
o LFBOutputSelectIndex, the LFB Group output port index to select
downstream LFB port. It is a 1-to-1 mapping with FEObject LFB's
table LFBTopology (See [RFC5812]) component FromPortIndex
corresponding to the port group mapping FromLFBID as IPv4NextHop
LFB instance.
5.3.2.3. Capabilities
This LFB does not have a list of capabilities
5.3.2.4. Events
This LFB does not have any events specified.
5.3.3. IPv6UcastLPM
The IPv6UcastLPM LFB abstracts the IPv6 unicast Longest Prefix Match
(LPM) process. The definition of this LFB is similar to the
IPv4UcastLPM LFB except that all IP addresses refer to IPv6
addresses.
This LFB also provides facilities to support users to implement
equal-cost multi-path routing (ECMP) or reverse path forwarding
(RPF). However, this LFB itself does not provide ECMP or RPF. To
fully implement ECMP or RPF, additional specific LFBs, like a
specific ECMP LFB or an RPF LFB, will have to be defined. This work
may be done in the future version of the document.
5.3.3.1. Data Handling
This LFB performs the IPv6 unicast LPM table look up. It always
expects as input IPv6 unicast packets from one singleton input known
as "PktsIn". The destination IPv6 address of an incoming packet is
used as search key to look up the IPv6 prefix table and generate a
hop selector. This hop selector result is associated to the packet
as a metadata and sent to downstream LFBs, and will usually be used
in downstream LFBs as a search key to find more next hop information.
Three singleton output LFB ports are defined.
The first singleton output known as "NormalOut" outputs IPv6 unicast
packets that succeed the LPM lookup (and got a hop selector). The
hop selector is associated with the packet as a metadata. Downstream
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from the LPM LFB is usually a next hop application LFB, like an
IPv6NextHop LFB.
The second singleton output known as "ECMPOut" is defined to provide
support for users wishing to implement ECMP.
An ECMP flag is defined in the LPM table to enable the LFB to support
ECMP. When a table entry is created with the flag set true, it
indicates this table entry is for ECMP only. A packet, which has
passed through this prefix lookup, will always output from "ECMPOut"
output port, with the hop selector being its lookup result. The
output will usually directly go to a downstream ECMP processing LFB,
where the hop selector can usually further generate optimized one or
multiple next hop routes by use of ECMP algorithms.
A default route flag is defined in the LPM table to enable the LFB to
support a default route as well as loose RPF. When this flag is set
true, the table entry is identified a default route which also
implies that the route is forbidden for RPF.
If a user wants to implement RPF on FE, a specific RPF LFB will have
to be defined. In such RPF LFB, a component can be defined as an
alias of the prefix table component of this LFB as described below.
The final singleton output is known as "ExceptionOut" and is defined
to allow exception packets to output here, along with an ExceptionID
metadata to indicate what caused the exception. Currently defined
exception types include:
o The packet failed the LPM lookup of the prefix table.
The upstream LFB of this LFB is usually IPv6Validator LFB. If RPF is
to be adopted, the upstream can be an RPF LFB, when defined.
The downstream LFB is usually an IPv6NextHop LFB. If ECMP is
adopted, the downstream can be an ECMP LFB, when defined.
5.3.3.2. Components
This LFB has two components.
The IPv6PrefixTable component is defined as an array component of the
LFB. Each row of the array contains an IPv6 address, a Prefix
length, a Hop Selector, an ECMP flag and a Default Route flag. The
ECMP flag is so the LFB can support ECMP. The default route flag is
for the LFB to support a default route and for loose RPF as described
earlier.
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The IPv6UcastLPMStats component is a struct component which collects
statistics information, including the total number of input packets
received, the IPv6 packets forwarded by this LFB and the number of IP
datagrams discarded due to no route found.
5.3.3.3. Capabilities
This LFB does not have a list of capabilities
5.3.3.4. Events
This LFB does not have any events specified.
5.3.4. IPv6NextHop
This LFB abstracts the process of selecting IPv6 next hop action.
5.3.4.1. Data Handling
The LFB abstracts the process of next hop information application to
IPv6 packets. It receives an IPv6 packet with an associated next hop
identifier (HopSelector), and uses the identifier to look up a next
hop table to find an appropriate output port from the LFB.
The LFB is expected to receive unicast IPv6 packets, via a singleton
input known as "PcktsIn" along with a HopSelector metadata which is
used as a table index to lookup the NextHop table.
Two output LFB ports are defined.
The first output is a group output port known as "SuccessOut". On
successful data processing the packet is sent out an LFB port from
within the LFB port group as selected by the LFBOutputSelectIndex
value of the matched table entry. The packet is sent to a downstream
LFB alongside with the L3PortID and MediaEncapInfoIndex metadata.
The second output is a singleton output port known as "ExceptionOut",
which will output packets for which the data processing failed, along
with an additional ExceptionID metadata to indicate what caused the
exception. Currently defined exception types include:
o The HopSelector for the packet is invalid.
o The packet failed lookup of the NextHop table even though the
HopSelector is valid.
o The MTU for outgoing interface is less than the packet size.
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Downstream LFB instances could be either a BasicMetadataDispatch
type, used to fanout to different LFB instances or a media
encapsulatation related type, such as an EtherEncap type or a
RedirectOut type. For example, when the downstream LFB is
BasicMetadataDispatch, and there exist Ethernet and other tunnel
Encapsulation downstream from BasicMetadataDispatch, then the
BasicMetadataDispatch LFB can use the L3PortID metadata (See section
below) to dispatch packets to the different Encapsulator LFBs.
5.3.4.2. Components
This LFB has only one component named IPv6NextHopTable which is
defined as an array. The array index of IPv6NextHopTable is used for
a HopSelector to find out a row of the table as the next hop
information. Each row of the array is a struct containing:
o The L3PortID, which is the ID of the Logical Output Port that is
passed onto the downstream LFB instance. This ID indicates what
port to the neighbor is as defined by L3. Usually this ID is used
for the NextHop LFB to distinguish packets that need different L2
encapsulating. For instance, some packets may require general
Ethernet encapsulation while others may require various types of
tunnel encapsulations. In such case, different L3PortIDs are
assigned to the packets and are as metadata passed to downstream
LFB. A BasicMetadataDispatch LFB(Section 5.5.1) may have to be
applied as the downstream LFB so as to dispatch packets to
different encapsulation LFB instances according to the L3PortIDs.
o MTU, the Maximum Transmission Unit for the outgoing port.
o NextHopIPAddr, the IPv6 next hop Address.
o MediaEncapInfoIndex, the index we pass onto the downstream
encapsulation LFB instance and that is used there as a search key
to lookup a table (typically media encapsulation related) for
further encapsulation information. Note that an encapsulation LFB
instance may not directly follow the NextHop LFB, but the index is
passed as a metadata associated, as such an encapsulation LFB
instance even further downstream to the NextHop LFB can still use
the index. In some cases, depending on implementation, the CE may
set the MediaEncapInfoIndex passed downstream to a value that will
fail lookup when it gets to a target encapsulation LFB; such a
lookup failure at that point is an indication that further
resolution is needed. For an example of this approach refer to
Section 7.2 which talks about ARP and mentions this approach.
o LFBOutputSelectIndex, the LFB Group output port index to select
downstream LFB port. It is a 1-to-1 mapping with FEObject LFB's
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table LFBTopology (See [RFC5812]) component FromPortIndex
corresponding to the port group mapping FromLFBID as IPv4NextHop
LFB instance.
5.3.4.3. Capabilities
This LFB does not have a list of capabilities
5.3.4.4. Events
This LFB does not have any events specified.
5.4. Redirect LFBs
Redirect LFBs abstract data packets transportation process between CE
and FE. Some packets output from some LFBs may have to be delivered
to CE for further processing, and some packets generated by CE may
have to be delivered to FE and further to some specific LFBs for data
path processing. According to [RFC5810], data packets and their
associated metadata are encapsulated in ForCES redirect message for
transportation between CE and FE. We define two LFBs to abstract the
process, a RedirectIn LFB and a RedirectOut LFB. Usually, in an LFB
topology of an FE, only one RedirectIn LFB instance and one
RedirectOut LFB instance exist.
5.4.1. RedirectIn
RedirectIn LFB abstracts the process for the CE to inject data
packets into the FE data path.
5.4.1.1. Data Handling
A RedirectIn LFB abstracts the process for the CE to inject data
packets into the FE LFB topology so as to input data packets into FE
data paths. From LFB topology point of view, the RedirectIn LFB acts
as a source point for data packets coming from CE, therefore
RedirectIn LFB is defined with a single output LFB port (and no input
LFB port).
The single output port of RedirectIn LFB is defined as a group output
type, with the name of "PktsOut". Packets produced by this output
will have arbitrary frame types decided by the CE which generated the
packets. Possible frames may include IPv4, IPv6, or ARP protocol
packets. The CE may associate some metadata to indicate the frame
types and may also associate other metadata to indicate various
information on the packets. Among them, there MUST exist a
'RedirectIndex' metadata, which is an integer acting as an index.
When the CE transmits the metadata along with the packet to a
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RedirectIn LFB, the LFB will read the RedirectIndex metadata and
output the packet to one of its group output port instance, whose
port index is indicated by this metadata. Any other metadata, in
addition to 'RedirectIndex', will be passed untouched along the
packet delivered by the CE to downstream LFB. This means the
'RedirectIndex' metadata from CE will be "consumed" by the RedirectIn
LFB and will not be passed to downstream LFB. Note that, a packet
from CE without a 'RedirectIndex' metadata associated will be dropped
by the LFB.
5.4.1.2. Components
There are no components defined for the current version of RedirectIn
LFB.
5.4.1.3. Capabilities
This LFB does not have a list of capabilities
5.4.1.4. Events
This LFB does not have any events specified.
5.4.2. RedirectOut
RedirectOut LFB abstracts the process for LFBs in the FE to deliver
data packets to the CE.
5.4.2.1. Data Handling
A RedirectOut LFB abstracts the process for LFBs in the FE to deliver
data packets to the CE. From the LFB's topology point of view, the
RedirectOut LFB acts as a sink point for data packets going to the
CE, therefore RedirectOut LFB is defined with a single input LFB port
(and no output LFB port).
The RedirectOut LFB has only one singleton input known as "PktsIn",
but is capable of receiving packets from multiple LFBs by
multiplexing this input. The input expects any kind of frame type
therefore the frame type has been specified as arbitrary, and also
all types of metadata are expected. All associated metadata produced
(but not consumed) by previous processed LFBs should be delivered to
CE via the ForCES protocol redirect message [RFC5810]. The CE can
decide on how to process the redirected packet by referencing the
associated metadata. As an example, a packet could be redirected by
the FE to the CE because the EtherEncap LFB is not able to resolve L2
information. The metadata "ExceptionID", created by the EtherEncap
LFB is passed along with the packet and should be sufficient for the
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CE to do the necessary processing and resolve the L2 entry required.
5.4.2.2. Components
There are no components defined for the current version of
RedirectOut LFB.
5.4.2.3. Capabilities
This LFB does not have a list of capabilities
5.4.2.4. Events
This LFB does not have any events specified.
5.5. General Purpose LFBs
5.5.1. BasicMetadataDispatch
The BasicMetadataDispatch LFB is defined to abstract the process in
which a packet is dispatched to some output path based on its
associated metadata value.
5.5.1.1. Data Handling
The BasicMetadataDispatch has only one singleton input known as
"PktsIn". Every input packet should be associated with a metadata
that will be used by the LFB to do the dispatch. This LFB contains a
Metadata ID component a dispatch table named MetadataDispatchTable,
all configured by the CE. The Metadata ID specifies which metadata
is to be used for dispatching packets. The MetadataDispatchTable
contains entries of a Metadata value and an OutputIndex, specifying
that the packet with the metadata value must go out from the LFB
group output port instance with the OutputIndex.
Two output LFB ports are defined.
The first output is a group output port known as "PktsOut". A packet
with its associated metadata having found an OutputIndex by
successfully looking up the dispatch table will be output to the
group port instance with the corresponding index.
The second output is a singleton output port known as "ExceptionOut",
which will output packets for which the data processing failed, along
with an additional ExceptionID metadata to indicate what caused the
exception. Currently defined exception types include:
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o There is no matching when looking up the metadata dispatch table.
As an example, if the CE decides to dispatch packets according to a
physical port ID (PHYPortID), the CE may set the ID of PHYPortID
metadata to the LFB first. Moreover, the CE also sets the PHYPortID
actual values (the metadata values) and assigned OutputIndex for the
values to the dispatch table in the LFB. When a packet arrives, a
PHYPortID metadata is found associated with the packet, the metadata
value is further used as a key to look up the dispatch table to find
out an output port instance for the packet.
Currently the BasicMetadataDispatch LFB only allows the metadata
value of the dispatch table entry be 32-bits integer. A metadata
with other types of value is not supported in this version. A more
complex metadata dispatch LFB may be defined in future version of the
library. In that LFB, multiple tuples of metadata with more value
types supported may be used to dispatch packets.
5.5.1.2. Components
This LFB has two components. One component is MetadataID and the
other is MetadataDispatchTable. Each row entry of the dispatch table
is a struct containing metadata value and the OutputIndex. Note that
currently, the metadata value is only allowed to be 32-bits integer.
The metadata value is also defined as a content key for the table.
The concept of content key is a searching key for tables which is
defined in the ForCES FE Model [RFC5812]. See this document and also
the ForCES Protocol [RFC5810] for more details on the definition and
use of a content key.
5.5.1.3. Capabilities
This LFB does not have a list of capabilities
5.5.1.4. Events
This LFB does not have any events specified.
5.5.2. GenericScheduler
This is a preliminary generic scheduler LFB for abstracting a simple
scheduling process.
5.5.2.1. Data Handling
There exist various kinds of scheduling strategies with various
implementations. As a base LFB library, this document only defines a
preliminary generic scheduler LFB for abstracting a simple scheduling
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process. Users may use this LFB as a basic scheduler LFB to further
construct more complex scheduler LFBs by means of inheritance as
described in [RFC5812].
Packets of any arbitrary frame type are received via a group input
known as "PktsIn" with no additional metadata expected. This group
input is capable of multiple input port instances. Each port
instance may be connected to different upstream LFB output.
Multiple queues reside at the input side, with every input LFB port
instance connected to one queue. Every queue is marked with a queue
ID, and the queue ID is exactly the same as the index of
corresponding input port instance. Scheduling disciplines are
applied to all queues and also all packets in the queues.
Scheduled packets are output from a singleton output port of the LFB
knows as "PktsOut" with no corresponding metadata.
More complex scheduler LFBs may be defined with more complex
scheduling disciplines by succeeding this LFB. For instance, a
priority scheduler LFB may be defined by inheriting this LFB and
defining a component to indicate priorities for all input queues.
5.5.2.2. Components
The QueueCount component is defined to specify the number of queues
to be scheduled.
The SchedulingDiscipline component is for the CE to specify a
scheduling discipline to the LFB. Currently defined scheduling
disciplines only include Round Robin (RR) strategy. The default
scheduling discipline is RR then.
The QueueStats component is defined to allow CE to query every queue
status of the scheduler. It is an array component and each row of
the array is a struct containing a queue ID. Currently defined queue
status includes the queue depth in packets and the queue depth in
bytes. Using the queue ID as the index, the CE can query every queue
for its used length in unit of packets or bytes.
5.5.2.3. Capabilities
The following capability is currently defined for the
GenericScheduler.
o The queue length limit providing the storage ability for every
queue.
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5.5.2.4. Events
This LFB does not have any events specified.
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6. XML for LFB Library
EtherPHYCop
The LFB describes an Ethernet port abstracted at
physical layer.It limits its physical media to copper.
Multiple virtual PHYs isn't supported in this LFB version.
1.0
EtherPHYIn
The input port of the EtherPHYCop LFB. It
expects any kind of Ethernet frame.
[EthernetAll]
EtherPHYOut
The output port of the EtherPHYCop LFB. It
can produce any kind of Ethernet frame and along with
the frame passes the ID of the Physical Port as
metadata to be used by the next LFBs.
[EthernetAll]
[PHYPortID]
PHYPortID
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The ID of the physical port that this LFB
handles.
uint32
AdminStatus
Admin status of the LFB
PortStatusValues
2
OperStatus
Operational status of the LFB.
PortStatusValues
AdminLinkSpeed
The link speed that the admin has requested.
LANSpeedType
LAN_SPEED_AUTO
OperLinkSpeed
The actual operational link speed.
LANSpeedType
AdminDuplexMode
The duplex mode that the admin has requested.
DuplexType
Auto
OperDuplexMode
The actual duplex mode.
DuplexType
CarrierStatus
The status of the Carrier. Whether the port
is linked with an operational connector.
boolean
false
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SupportedLinkSpeed
Supported Link Speeds
LANSpeedType
SupportedDuplexMode
Supported Duplex Modes
DuplexType
PHYPortStatusChanged
When the status of the Physical port is
changed,the LFB sends the new status.
OperStatus
OperStatus
LinkSpeedChanged
When the operational speed of the link
is changed, the LFB sends the new operational link
speed.
OperLinkSpeed
OperLinkSpeed
DuplexModeChanged
When the operational duplex mode
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is changed, the LFB sends the new operational mode.
OperDuplexMode
OperDuplexMode
EtherMACIn
An LFB abstracts an Ethernet port at MAC data link
layer. It specifically describes Ethernet processing functions
like MAC address locality check, deciding if the Ethernet
packets should be bridged, provide Ethernet layer flow control,
etc.Multiple virtual MACs isn't supported in this LFB
version.
1.0
EtherPktsIn
The input port of the EtherMACIn. It
expects any kind of Ethernet frame.
[EthernetAll]
[PHYPortID]
NormalPathOut
The normal output port of the EtherMACIn.
It can produce any kind of Ethernet frame and along
with the frame passes the ID of the Physical Port as
metadata to be used by the next LFBs.
[EthernetAll]
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[PHYPortID]
L2BridgingPathOut
The Bridging Output Port of the EtherMACIn.
It can produce any kind of Ethernet frame and along
with the frame passes the ID of the Physical Port as
metadata to be used by the next LFBs.
[EthernetAll]
[PHYPortID]
AdminStatus
Admin status of the port
PortStatusValues
2
LocalMACAddresses
Local Mac addresses
IEEEMAC
L2BridgingPathEnable
Is the LFB doing L2 Bridging?
boolean
false
PromiscuousMode
Is the LFB in Promiscuous Mode?
boolean
false
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TxFlowControl
Transmit flow control
boolean
false
RxFlowControl
Receive flow control
boolean
false
MACInStats
MACIn statistics
MACInStatsType
EtherClassifier
This LFB abstracts the process to decapsulate
Ethernet packets and classify the data packets into
various network layer data packets according to information
included in the Ethernet packets headers.
1.0
EtherPktsIn
Input port for data packet.
[EthernetAll]
[PHYPortID]
[
LogicalPortID]
ClassifyOut
Output port for classification.
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[Arbitrary]
[PHYPortID]
[SrcMAC]
[DstMAC]
[EtherType]
[VlanID]
[VlanPriority]
EtherDispatchTable
Ether classify dispatch table
EtherDispatchTableType
VlanInputTable
Vlan input table
VlanInputTableType
EtherClassifyStats
Ether classify statistic table
EtherClassifyStatsTableType
EtherEncap
This LFB abstracts the process to encapsulate IP
packets to Ethernet packets according to the L2 information.
1.0
EncapIn
A Single Packet Input
[IPv4]
[IPv6]
[MediaEncapInfoIndex]
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[
VlanPriority]
SuccessOut
Output port for Packets which have found
Ethernet L2 information and have been successfully
encapsulated to an Ethernet packet.
[IPv4]
[IPv6]
[L2PortID]
ExceptionOut
All packets that fail with the other
operations in this LFB are output via this port.
[IPv4]
[IPv6]
[ExceptionID]
[MediaEncapInfoIndex]
[VlanPriority]
EncapTable
Ethernet Encapsulation table.
EncapTableType
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EtherMACOut
EtherMACOut LFB abstracts an Ethernet port at MAC
data link layer. It specifically describes Ethernet packet
output process. Ethernet output functions are closely related
to Ethernet input functions, therefore some components
defined in this LFB are actually alias of EtherMACIn LFB.
1.0
EtherPktsIn
The Input Port of the EtherMACIn. It expects
any kind of Ethernet frame.
[EthernetAll]
[PHYPortID]
EtherPktsOut
The Normal Output Port of the EtherMACOut. It
can produce any kind of Ethernet frame and along with
the frame passes the ID of the Physical Port as
metadata to be used by the next LFBs.
[EthernetAll]
[PHYPortID]
AdminStatus
Admin status of the port. It is the alias of
"AdminStatus" component defined in EtherMACIn.
PortStatusValues
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MTU
Maximum transmission unit.
uint32
TxFlowControl
Transmit flow control. It is the alias of
"TxFlowControl" component defined in EtherMACIn.
boolean
RxFlowControl
Receive flow control. It is the alias of
"RxFlowControl" component defined in EtherMACIn.
boolean
MACOutStats
MACOut statistics
MACOutStatsType
IPv4Validator
An LFB that performs IPv4 packets validation
according to RFC1812. At the same time, ipv4 unicast and
multicast are classified in this LFB.
1.0
ValidatePktsIn
Input port for data packet.
[Arbitrary]
IPv4UnicastOut
Output for IPv4 unicast packet.
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[IPv4Unicast]
IPv4MulticastOut
Output for IPv4 multicast packet.
[IPv4Multicast]
ExceptionOut
Output for exception packet.
[IPv4]
[ExceptionID]
FailOut
Output for failed validation packet.
[IPv4]
[ValidateErrorID]
IPv4ValidatorStats
IPv4 validator statistics information.
IPv4ValidatorStatsType
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IPv6Validator
An LFB that performs IPv6 packets validation
according to RFC2460. At the same time, ipv6 unicast and
multicast are classified in this LFB.
1.0
ValidatePktsIn
Input port for data packet.
[Arbitrary]
IPv6UnicastOut
Output for IPv6 unicast packet.
[IPv6Unicast]
IPv6MulticastOut
Output for IPv6 multicast packet.
[IPv6Multicast]
ExceptionOut
Output for exception packet.
[IPv6]
[ExceptionID]
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FailOut
Output for failed validation packet.
[IPv6]
[ValidateErrorID]
IPv6ValidatorStats
IPv6 validator statistics information.
IPv6ValidatorStatsType
IPv4UcastLPM
An LFB that performs IPv4 Longest Prefix Match
Lookup.It is defined to provide some facilities to support
users to implement equal-cost multi-path routing(ECMP) or
reverse path forwarding (RPF).
1.0
PktsIn
A Single Packet Input
[IPv4Unicast]
NormalOut
This output port is connected with
IPv4NextHop LFB
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[IPv4Unicast]
[HopSelector]
ECMPOut
This output port is connected with ECMP LFB,
if there is ECMP LFB in the FE.
[IPv4Unicast]
[HopSelector]
ExceptionOut
The output for the packet if an exception
occurs
[IPv4Unicast]
[ExceptionID]
IPv4PrefixTable
The IPv4 prefix table.
IPv4PrefixTableType
IPv4UcastLPMStats
Statistics for IPv4 Unicast Longest Prefix
Match
IPv4UcastLPMStatsType
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IPv6UcastLPM
An LFB that performs IPv6 Longest Prefix Match
Lookup.It is defined to provide some facilities to support
users to implement equal-cost multi-path routing(ECMP) or
reverse path forwarding (RPF).
1.0
PktsIn
A Single Packet Input
[IPv6Unicast]
NormalOut
This output port is connected with
IPv6NextHop LFB
[IPv6Unicast]
[HopSelector]
ECMPOut
This output port is connected with ECMP LFB,
if there is ECMP LFB in the FE.
[IPv6Unicast]
[HopSelector]
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ExceptionOut
The output for the packet if an exception
occurs
[IPv6Unicast]
[ExceptionID]
IPv6PrefixTable
The IPv6 prefix table.
IPv6PrefixTableType
IPv6UcastLPMStats
Statistics for IPv6 Unicast Longest Prefix
Match
IPv6UcastLPMStatsType
IPv4NextHop
This LFB abstracts the process of selecting ipv4
next hop action. It receives an IPv4 packet with an
associated next hop ID, and uses the ID to look up a next
hop table to find an appropriate output port from the LFB.
1.0
PktsIn
A Single Packet Input
[IPv4Unicast]
[HopSelector]
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SuccessOut
The output for the packet if it is valid to be
forwarded
[IPv4Unicast]
[L3PortID]
[NextHopIPv4Addr]
[
MediaEncapInfoIndex]
ExceptionOut
The output for the packet if an exception
occurs
[IPv4Unicast]
[ExceptionID]
IPv4NextHopTable
The next hop table.
IPv4NextHopTableType
IPv6NextHop
The LFB abstracts the process of next hop
information application to IPv6 packets. It receives an IPv4
packet with an associated next hop ID, and uses the ID to
look up a next hop table to find an appropriate output port
from the LFB..
1.0
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PktsIn
A single packet input.
[IPv6Unicast]
[HopSelector]
SuccessOut
The output for the packet if it is valid to
be forwarded
[IPv6Unicast]
[L3PortID]
[NextHopIPv6Addr]
[
MediaEncapInfoIndex]
ExceptionOut
The output for the packet if an exception
occurs
[IPv6Unicast]
[ExceptionID]
IPv6NextHopTable
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The next hop table.
IPv6NextHopTableType
RedirectIn
The RedirectIn LFB abstracts the process for CE to
inject data packets into FE LFB topology, so as to input data
packets into FE data paths. CE may associate some
metadata to data packets to indicate various information on
the packets. Among them, there MUST exist a 'RedirectIndex'
metadata, which is an integer acting as an output port index.
1.0
PktsOut
This output group sends the redirected packet
in the data path.
[Arbitrary]
RedirectOut
The LFB abstracts the process for LFBs in
FE to deliver data packets to CE. All metadata
associated with the input packets will be delivered to CE
via the redirect message of ForCES protocol [RFC5810].
1.0
PktsIn
This input receives packets to send to
the CE.
[Arbitrary]
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BasicMetadataDispatch
This LFB provides the function to dispatch input
packets to a group output according to a metadata and a
dispatch table.This LFB currently only allow a metadata with
an interger value to be used for dispatch.
1.0
PktsIn
Input port for data packet.
[Arbitrary]
[Arbitrary]
PktsOut
Data packet output
[Arbitrary]
MetadataID
the metadata ID for dispatching
uint32
MetadataDispatchTable
Metadata dispatch table.
MetadataDispatchTableType
GenericScheduler
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This is a preliminary generic scheduler LFB for
abstracting a simple scheduling process.Users may use this
LFB as a basic scheduler LFB to further construct more
complex scheduler LFBs by means of inheritance as described
in RFC5812.
1.0
PktsIn
Input port for data packet.
[Arbitrary]
PktsOut
Data packet output.
[Arbitrary]
QueueCount
The number of queues to be scheduled.
uint32
SchedulingDiscipline
the Scheduler discipline.
SchdDisciplineType
QueueStats
Current statistics for all queues
QueueStatsTableType
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QueueLenLimit
Maximum length of each queue,the unit is
byte.
uint32
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7. LFB Class Use Cases
This section demonstrates examples on how the LFB classes defined by
the Base LFB library in Section 6 can be applied to achieve some
typical router functions. The functions demonstrated are:
o IPv4 forwarding
o ARP processing
It is assumed the LFB topology on the FE described has already been
established by the CE and maps to the use cases illustrated in this
section.
The use cases demonstrated in this section are mere examples and by
no means should be treated as the only way one would construct router
functionality from LFBs; based on the capability of the FE(s), a CE
should be able to express different NE applications.
7.1. IPv4 Forwarding
Figure 1 (Section 3.2.3) shows a typical IPv4 forwarding processing
path by use of the base LFB classes.
A number of EtherPHYCop LFB(Section 5.1.1) instances are used to
describe physical layer functions of the ports. PHYPortID metadata
is generated by EtherPHYCop LFB and is used by all the subsequent
downstream LFBs. An EtherMACIn LFB(Section 5.1.2), which describe
the MAC layer processing, follows every EtherPHYCop LFB. The
EtherMACIn LFB may do a locality check of MAC addresses if the CE
configures the appropriate EtherMACIn LFB component.
Ethernet packets out of the EtherMACIn LFB are sent to an
EtherClassifier LFB (Section 5.1.3) to be decapsulated and classified
into network layer types like IPv4, IPv6, ARP, etc. In the example
use case, every physical Ethernet interface is associated with one
Classifier instance; although not illustrated, it is also feasible
that all physical interfaces are associated with only one Ethernet
Classifier instance.
EtherClassifier uses the PHYPortID metadata, the Ethernet type of the
input packet, and VlanID (if present in the input Ethernet packets),
to decide the packet network layer type and the LFB output port to
the downstream LFB. The EtherClassifier LFB also assigns a new
logical port ID metadata to the packet for later use. The
EtherClassifier may also generate some new metadata for every packet
like EtherType, SrcMAC, DstMAC, LogicPortID, etc for consumption by
downstream LFBs.
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If a packet is classified as an IPv4 packet, it is sent downstream to
an IPv4Validator LFB (Section 5.2.1) to validate the IPv4 packet. In
the validator LFB, IPv4 packets are validated and are additionally
classified into either IPv4 unicast packets or multicast packets.
IPv4 unicast packets are sent to downstream to the IPv4UcastLPM LFB
(Section 5.3.1).
The IPv4UcastLPM LFB is where the longest prefix match decision is
made, and a next hop selection is selected. The nexthop ID metadata
is generated by the IPv4UcastLPM LFB to be consumed downstream by the
IPv4NextHop LFB (Section 5.3.2).
The IPv4NextHop LFB uses the nexthop ID metadata to do derive where
the packet is to go next and the media encapsulation type for the
port, etc. The IPv4NextHop LFB generates the L3PortID metadata used
to identify a next hop output physical/logical port. In the example
use case, the next hop output port is an Ethernet type; as a result,
the packet and its L3 port ID metadata are sent downstream to an
EtherEncap LFB (Section 5.1.4).
The EtherEncap LFB encapsulates the incoming packet into an Ethernet
frame. A BasicMetadataDispatch LFB (Section 5.5.1) follows the
EtherEncap LFB. The BasicMetadataDispatch LFB is where packets are
finally dispatched to different output physical/logical ports based
on the L3PortID metadata sent to the LFB.
7.2. ARP processing
Figure 2 shows the processing path for ARP protocol in the case the
CE implements the ARP processing function. By no means is this the
only way ARP processing could be achieved; as an example ARP
processing could happen at the FE - but that discussion is out of
scope for this use case.
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+---+ +---+
| | ARP packets | |
| |------------------------+--->| | To CE
...-->| | . | | |
| | . | +---+
| | . | RedirectOut
+---+ |
Ether EtherEncap | IPv4 packets lack
Classifier +---+ | address resolution information
| | |
Packets need | |--------->---+
...--------->| |
L2 Encapsulation| |
+---+ | | +------+
| | +-->| |--+ +---+ |Ether |
| | | +---+ | | |--------->|MACOut|-->...
From CE| |--+ +-->| | . +------+
| |ARP Packets | | .
| |from CE | | . +------+
| | | |--------> |Ether |-->...
+---+ +---+ |MACOut|
RedirectIn BasicMetadata +------+
Dispatch
Figure 2: LFB use case for ARP
There are two ways ARP processing could be triggered in the CE as
illustrated in Figure 2:
o ARP packets arriving from outside of the NE.
o IPV4 packets failing to resolve within the FE.
ARP packets from network interfaces are filtered out by
EtherClassifier LFB. The classified ARP packets and associated
metadata are then sent downstream to the RedirectOut LFB
(Section 5.4.2) to be transported to CE.
The EtherEncap LFB, as described earlier, receives packets that need
Ethernet L2 encapsulating. When the EtherEncap LFB fails to find the
necessary L2 Ethernet information to encapsulate the packet with, it
outputs the packet to its ExceptionOut LFB port. Downstream to
EtherEncap LFB's ExceptionOut LFB port is the RedirectOut LFB which
transports the packet to the CE (Section 5.1.4 on EtherEncap LFB for
details).
To achieve its goal, the CE needs to generate ARP request and
response packets and send them to external (to the NE) networks. ARP
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request and response packets from the CE are redirected to an FE via
a RedirectIn LFB (Section 5.4.1).
As was the case with forwarded IPv4 packets, outgoing ARP packets are
also encapsulated to Ethernet format by the EtherEncap LFB, and then
dispatched to different interfaces via a BasicMetadataDispatch LFB.
The BasicMetadataDispatch LFB dispatches the packets according to the
L3PortID metadata included in every ARP packet sent from CE.
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8. Contributors
The authors would like to thank Jamal Hadi Salim, Ligang Dong, and
Fenggen Jia who made major contributions to the development of this
document.
Jamal Hadi Salim
Mojatatu Networks
Ottawa, Ontario
Canada
Email: hadi@mojatatu.com
Ligang Dong
Zhejiang Gongshang University
149 Jiaogong Road
Hangzhou 310035
P.R.China
Phone: +86-571-28877751
EMail: donglg@mail.zjgsu.edu.cn
Fenggen Jia
National Digital Switching Center(NDSC)
Jianxue Road
Zhengzhou 452000
P.R.China
EMail: jfg@mail.ndsc.com.cn
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9. Acknowledgements
This document is based on earlier documents from Joel Halpern, Ligang
Dong, Fenggen Jia and Weiming Wang.
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10. IANA Considerations
IANA has created a registry of ForCES LFB Class Names and the
corresponding ForCES LFB Class Identifiers, with the location of the
definition of the ForCES LFB Class, in accordance with the rules to
use the namespace.
The LFB library in this document needs for unique class names and
numeric class identifiers of all LFBs. Besides, this document also
needs to define the following namespaces:
o Metadata ID, defined in Section 4.3 and Section 4.4
o Exception ID, defined in Section 4.4
o Validate Error ID, defined in Section 4.4
10.1. LFB Class Names and LFB Class Identifiers
LFB classes defined by this document belongs to IETF defined LFBs by
Standard Track RFCs. According to IANA, the identifier namespace for
these LFB classes is from 3 to 65535.
The assignment of LFB class names and LFB class identifiers is as in
the following table.
+-----------+---------------+------------------------+--------------+
| LFB Class | LFB Class Name| Description | Reference |
| Identifier| | | |
+-----------+---------------+------------------------+--------------+
| 3 | EtherPHYCop | Define an Ethernet port| RFC????(this|
| | | abstracted at physical | document) |
| | | layer | Section 5.1.1|
| | | -------------- | |
| 4 | EtherMACIn | Define an Ethernet | RFC???? |
| | | input port at MAC data | Section 5.1.2|
| | | link layer | |
| | | -------------- | |
| 5 |EtherClassifier| Define the process to | RFC???? |
| | | decapsulate Ethernet | Section 5.1.3|
| | | packets and classify | |
| | | the packets | |
| | | -------------- | |
| 6 | EtherEncap | Define the process to | RFC???? |
| | | encapsulate IP packets | Section 5.1.4|
| | | to Ethernet packets | |
| | | -------------- | |
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| 7 | EtherMACOut | Define an Ethernet | RFC ???? |
| | | output port at MAC | Section 5.1.5|
| | | data link layer | |
| | | -------------- | |
| 8 | IPv4Validator | Perform IPv4 packets | RFC ???? |
| | | validation. | Section 5.2.1|
| | | -------------- | |
| 9 | IPv6Validator | Perform IPv6 packets | RFC ???? |
| | | validation | Section 5.2.2|
| | | -------------- | |
| 10 | IPv4UcastLPM | Perform IPv4 Longest | RFC ???? |
| | | Prefix Match Lookup | Section 5.3.1|
| | | -------------- | |
| 11 | IPv6UcastLPM | Perform IPv6 Longest | RFC ???? |
| | | Prefix Match Lookup | Section 5.3.3|
| | | -------------- | |
| 12 | IPv4NextHop | Define the process of | RFC ??? |
| | | selecting Ipv4 next hop| Section 5.3.2|
| | | action | |
| | | -------------- | |
| 13 | IPv6NextHop | Define the process of | RFC ??? |
| | | selecting Ipv6 next hop| Section 5.3.4|
| | | action | |
| | | -------------- | |
| 14 | RedirectIn | Define the process for | RFC ??? |
| | | CE to inject data | Section 5.4.1|
| | | packets into FE LFB | |
| | | topology | |
| | | -------------- | |
| 15 | RedirectOut | Define the process for | RFC ??? |
| | | LFBs in FE to deliver | Section 5.4.2|
| | | data packets to CE | |
| | | -------------- | |
| 16 |BasicMetadata | Dispatch input packets | RFC ??? |
| |Dispatch | to a group output | Section 5.5.1|
| | | according to a metadata| |
| | | -------------- | |
| 17 |Generic | Define a preliminary | RFC ???? |
| |Scheduler | generic scheduling | Section 5.5.2|
| | | process | |
+-----------+---------------+------------------------+--------------+
Table 1
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10.2. Metadata ID
The Metadata ID namespace is 32 bits long. The following is the
guideline for managing the namespace.
Metadata ID 0x00000000-0x7FFFFFFF
Metadata with IDs in this range are Specification Required
[RFC5226]. A metadata ID using this range MUST be documented in
an RFC or other permanent and readily available references.
Values assigned by this specification:
+--------------+-------------------------+--------------------------+
| Value | Name | Definition |
+--------------+-------------------------+--------------------------+
| 0x00000001 | PHYPortID | See Section 4.4 |
| 0x00000002 | SrcMAC | See Section 4.4 |
| 0x00000003 | DstMAC | See Section 4.4 |
| 0x00000004 | LogicalPortID | See Section 4.4 |
| 0x00000005 | EtherType | See Section 4.4 |
| 0x00000006 | VlanID | See Section 4.4 |
| 0x00000007 | VlanPriority | See Section 4.4 |
| 0x00000008 | NexthopIPv4Addr | See Section 4.4 |
| 0x00000009 | NexthopIPv6Addr | See Section 4.4 |
| 0x0000000A | HopSelector | See Section 4.4 |
| 0x0000000B | ExceptionID | See Section 4.4 |
| 0x0000000C | ValidateErrorID | See Section 4.4 |
| 0x0000000D | L3PortID | See Section 4.4 |
| 0x0000000E | RedirectIndex | See Section 4.4 |
| 0x0000000F | MediaEncapInfoIndex | See Section 4.4 |
+--------------+-------------------------+--------------------------+
Table 2
Metadata ID 0x80000000-0xFFFFFFFF
Metadata IDs in this range are reserved for vendor private
extensions and are the responsibility of individuals.
10.3. Exception ID
The Exception ID namespace is 32 bits long. The following is the
guideline for managing the namespace.
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Exception ID 0x00000000-0x7FFFFFFF
Exception IDs in this range are Specification Required [RFC5226].
An exception ID using this range MUST be documented in an RFC or
other permanent and readily available references.
Values assigned by this specification:
+--------------+---------------------------------+------------------+
| Value | Name | Definition |
+--------------+---------------------------------+------------------+
| 0x00000000 | AnyUnrecognizedExceptionCase | See Section 4.4 |
| 0x00000001 | ClassifyNoMatching | See Section 4.4 |
| 0x00000002 | MediaEncapInfoIndexInvalid | See Section 4.4 |
| 0x00000003 | EncapTableLookupFailed | See Section 4.4 |
| 0x00000004 | BadTTL | See Section 4.4 |
| 0x00000005 | IPv4HeaderLengthMismatch | See Section 4.4 |
| 0x00000006 | RouterAlertOptions | See Section 4.4 |
| 0x00000007 | IPv6HopLimitZero | See Section 4.4 |
| 0x00000008 | IPv6NextHeaderHBH | See Section 4.4 |
| 0x00000009 | SrcAddressExecption | See Section 4.4 |
| 0x0000000A | DstAddressExecption | See Section 4.4 |
| 0x0000000B | LPMLookupFailed | See Section 4.4 |
| 0x0000000C | HopSelectorInvalid | See Section 4.4 |
| 0x0000000D | NextHopLookupFailed | See Section 4.4 |
| 0x0000000E | FragRequired | See Section 4.4 |
| 0x0000000F | MetadataNoMatching | See Section 4.4 |
+--------------+---------------------------------+------------------+
Table 3
Exception ID 0x80000000-0xFFFFFFFF
Exception IDs in this range are reserved for vendor private
extensions and are the responsibility of individuals.
10.4. Validate Error ID
The Validate Error ID namespace is 32 bits long. The following is
the guideline for managing the namespace.
Validate Error ID 0x00000000-0x7FFFFFFF
Validate Error IDs in this range are Specification Required
[RFC5226]. A Validate Error ID using this range MUST be
documented in an RFC or other permanent and readily available
references.
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Values assigned by this specification:
+--------------+---------------------------------+------------------+
| Value | Name | Definition |
+--------------+---------------------------------+------------------+
| 0x00000000 | AnyUnrecognizedValidateErrorCase| See Section 4.4 |
| 0x00000001 | InvalidIPv4PacketSize | See Section 4.4 |
| 0x00000002 | NotIPv4Packet | See Section 4.4 |
| 0x00000003 | InvalidIPv4HeaderLengthSize | See Section 4.4 |
| 0x00000004 | InvalidIPv4LengthFieldSize | See Section 4.4 |
| 0x00000005 | InvalidIPv4Checksum | See Section 4.4 |
| 0x00000006 | InvalidIPv4SrcAddr | See Section 4.4 |
| 0x00000007 | InvalidIPv4DstAddr | See Section 4.4 |
| 0x00000008 | InvalidIPv6PakcetSize | See Section 4.4 |
| 0x00000009 | NotIPv6Packet | See Section 4.4 |
| 0x0000000A | InvalidIPv6SrcAddr | See Section 4.4 |
| 0x0000000B | InvalidIPv6DstAddr | See Section 4.4 |
+--------------+---------------------------------+------------------+
Table 4
Validate Error ID 0x80000000-0xFFFFFFFF
Validate Error IDs in this range are reserved for vendor private
extensions and are the responsibility of individuals.
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11. Security Considerations
The ForCES framework document [RFC3746] provides a comprehensive
security analysis for the overall ForCES architecture. For example,
the ForCES protocol entities must be authenticated per the ForCES
requirements before they can access the information elements
described in this document via ForCES. Access to the information
contained in this document is accomplished via the ForCES
protocol[RFC5810], which is defined in separate documents, and thus
the security issues will be addressed there.
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12. References
12.1. Normative References
[RFC5810] Doria, A., Hadi Salim, J., Haas, R., Khosravi, H., Wang,
W., Dong, L., Gopal, R., and J. Halpern, "Forwarding and
Control Element Separation (ForCES) Protocol
Specification", RFC 5810, March 2010.
[RFC5812] Halpern, J. and J. Hadi Salim, "Forwarding and Control
Element Separation (ForCES) Forwarding Element Model",
RFC 5812, March 2010.
12.2. Informative References
[RFC1122] Braden, R., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, October 1989.
[RFC1812] Baker, F., "Requirements for IP Version 4 Routers",
RFC 1812, June 1995.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
July 2003.
[RFC3654] Khosravi, H. and T. Anderson, "Requirements for Separation
of IP Control and Forwarding", RFC 3654, November 2003.
[RFC3746] Yang, L., Dantu, R., Anderson, T., and R. Gopal,
"Forwarding and Control Element Separation (ForCES)
Framework", RFC 3746, April 2004.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
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Authors' Addresses
Weiming Wang
Zhejiang Gongshang University
18 Xuezheng Str., Xiasha University Town
Hangzhou, 310018
P.R.China
Phone: +86-571-28877721
Email: wmwang@zjgsu.edu.cn
Evangelos Haleplidis
University of Patras
Patras,
Greece
Email: ehalep@ece.upatras.gr
Kentaro Ogawa
NTT Corporation
Tokyo,
Japan
Email: ogawa.kentaro@lab.ntt.co.jp
Chuanhuang Li
Hangzhou BAUD Networks
408 Wen-San Road
Hangzhou, 310012
P.R.China
Phone: +86-571-28877751
Email: chuanhuang_li@zjgsu.edu.cn
Halpern Joel
Ericsson
P.O. Box 6049
Leesburg, 20178
VA
Phone: +1 703 371 3043
Email: joel.halpern@ericsson.com
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