NVO3 Working Group G. Mirsky
Internet-Draft ZTE Corp.
Intended status: Standards Track N. Kumar
Expires: August 31, 2017 D. Kumar
Cisco Systems, Inc.
M. Chen
Y. Li
Huawei Technologies
D. Mozes
Mellanox Technologies Ltd.
D. Dolson
February 27, 2017

Echo Request and Echo Reply for Overlay Networks


This document defines Overlay Echo Request and Echo Reply that enable on-demand Continuity Check, Connectivity Verification among other operations in overlay networks.

Status of This Memo

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This Internet-Draft will expire on August 31, 2017.

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Table of Contents

1. Introduction

Operations, Administration, and Maintenance (OAM) toolset provides methods for fault management and performance monitoring in each layer of the network, in order to improve their ability to support services with guaranteed and strict Service Level Agreements (SLAs) while reducing operational costs.

1.1. Conventions used in this document

1.1.1. Terminology

Term "Overlay OAM" used in this document interchangeably with longer version "set of OAM protocols, methods and tools for Overlay networks". And "Overlay ping" is used intercheangeably with longer version Overlay Echo Request/Reply.

CC Continuity Check

CV Connectivity Verification

ECMP Equal Cost Multipath

FM Fault Management

Geneve Generic Network Virtualization Encapsulation

GUE Generic UDP Encapsulation

MPLS Multiprotocol Label Switching

NVO3 Network Virtualization Overlays

OAM Operations, Administration, and Maintenance

SFC Service Function Chaining

SFP Service Function Path

VXLAN Virtual eXtensible Local Area Network

VXLAN-GPE Generic Protocol Extension for VXLAN

1.1.2. Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].

2. On-demand Continuity Check and Connectivity Verification

2.1. Requirements Towards On-demand CC/CV OAM

Availability, not as performance metric, is understood as ability to reach the node, i.e. the fact that path between ingress and egress does exist. Such OAM mechanism also referred as Continuity Check (CC). Connectivity Verification (CV) extends Continuity Check functionality in order to provide confirmation that the desired source is connected to the desired sink.

Echo Request/Reply OAM mechanism enables detection of the loss of continuity defect, its localization and collection information in order to discover root cause. These are requirements considered:

2.2. Proposed Solution

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      |         Version Number        |         Global Flags          |
      | Message Type  |   Reply mode  |  Return Code  | Return S.code |
      |                        Sender's Handle                        |
      |                         Sequence Number                       |
      ~                              TLVs                             ~

Figure 1: Overlay OAM Ping format

The format of the Echo Request/Echo Reply control packet is to support ping and traceroute functionality in overlay networks Figure 1 resembles the format of MPLS LSP Ping [RFC4379] with some exceptions.

The interpretation of the fields is as following:

2.3. Overlay Echo Request Transmission

Overlay Echo Request control packet MUST use the appropriate encapsulation of the monitored overlay network. Overlay network encpsulation MUST identify Echo Request as OAM packet. Overlay encapsulation uses different methods to identify OAM payload [I-D.ietf-nvo3-vxlan-gpe], [I-D.ietf-nvo3-gue], [I-D.ietf-nvo3-geneve], [I-D.ietf-sfc-nsh],[I-D.ietf-bier-mpls-encapsulation]. Overlay network's header MUST be immediately followed by the Overlay OAM Header [I-D.ooamdt-rtgwg-ooam-header]. Message Type field in the Overlay OAM Header MUST be set to Overlay Echo Request value (TBA2).

Value of the Reply Mode field MAY be set to:

2.4. Overlay Echo Request Reception

2.5. Overlay Echo Reply Transmission

The Reply Mode field directs whether and how the Echo Reply message should be sent. The sender of the Echo Request MAY use TLVs to request that corresponding Echo Reply be sent using the specified path. Value TBA3 is referred as "Do not reply" mode and suppresses transmission of Echo Reply packet. Default value (TBA5) for the Reply mode field requests the responder to send the Echo Reply packet out-of-band as IPv4 or IPv6 UDP packet. [Selection of destination and source IP addresses and UDP port numbers to be provided in the next update.]

2.6. Overlay Echo Reply Reception

3. IANA Considerations

3.1. Overlay Echo Request/Echo Reply Type

IANA is requested to assign new type from the Overlay OAM Protocol Types registry as follows:

Overlay Echo Request/Echo Reply Type
Value Description Reference
TBA1 Overlay Echo Request/Echo Reply This document

3.2. Overlay Ping Parameters

IANA is requested to create new Overlay Echo Request/Echo Reply Parameters registry.

3.3. Overlay Echo Request/Echo Reply Message Types

IANA is requested to create in the Overlay Echo Request/Echo Reply Parameters registry the new sub-registry Message Types. All code points in the range 1 through 191 in this registry shall be allocated according to the "IETF Review" procedure as specified in [RFC5226] and assign values as follows:

Overlay Echo Request/Echo Reply Message Types
Value Description Reference
0 Reserved
TBA2 Overlay Echo Request This document
TBA3 Overlay Echo Reply This document
TBA3+1-191 Unassigned IETF Review
192-251 Unassigned First Come First Served
252-254 Unassigned Private Use
255 Reserved

3.4. Overlay Echo Reply Modes

IANA is requested to create in the Overlay Echo Request/Echo Reply Parameters registry the new sub-registry Reply Modes All code points in the range 1 through 191 in this registry shall be allocated according to the "IETF Review" procedure as specified in [RFC5226] and assign values as follows:

Overlay Echo Reply Modes
Value Description Reference
0 Reserved
TBA4 Do Not Reply This document
TBA5 Reply via an IPv4/IPv6 UDP Packet This document
TBA6 Reply via Application Level Control Channel This document
TBA7 Reply via Specified Path This document
TBA7+1-191 Unassigned IETF Review
192-251 Unassigned First Come First Served
252-254 Unassigned Private Use
255 Reserved

4. Security Considerations

Overlay Echo Request/Reply operates withing the domain of the overlay network and thus inherits any security considerations that apply to the use of that overlay technology and, consequently, underlay data plane. Also, the security needs for Overlay Echo Request/Reply are similar to those of ICMP ping [RFC0792], [RFC4443] and MPLS LSP ping [I-D.ietf-mpls-rfc4379bis].

There are at least three approaches of attacking a node in the overlay network using the mechanisms defined in the document. One is a Denial-of-Service attack, by sending Overlay ping to overload a node in the overlay network. The second may use spoofing, hijacking, replying, or otherwise tampering with Overlay Echo Requests and/or Replies to misrepresent, alter operator's view of the state of the overlay network. The third is an unauthorized source using an Overlay Echo Request/Reply to obtain information about the overlay and/or underlay network.

To mitigate potential Denial-of-Service attacks, it is RECOMMENDED that implementations throttle the Overlay ping traffic going to the control plane.

Reply and spoofing attacks involving faking or replying Overlay Echo Reply messages would have to match the Sender's Handle and Sequence Number of an outstanding Overlay Echo Request message which is highly unlikely. Thus the non-matching reply would be discarded. But since "even a broken clock is right twice a day" implementations MAY use Timestamp control block [I-D.ooamdt-rtgwg-ooam-header] to validate the TimeStamp Sent by requiring an exact match on this field.

To protect against unauthorized sources trying to obtain information about the overlay and/or underlay an implementation MAY check that the source of the Echo Request is indeed part of the overlay domain.

5. Contributors

Work on this documented started by Overlay OAM Design Team with contributions from:

Carlos Pignataro

Cisco Systems, Inc.


Santosh Pallagatti


Erik Nordmark

Arista Networks


Ignas Bagdonas


6. Acknowledgment


7. References

7.1. Normative References

[I-D.ietf-bier-mpls-encapsulation] Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J., Aldrin, S. and I. Meilik, "Encapsulation for Bit Index Explicit Replication in MPLS and non-MPLS Networks", Internet-Draft draft-ietf-bier-mpls-encapsulation-06, December 2016.
[I-D.ietf-nvo3-geneve] Gross, J., Ganga, I. and T. Sridhar, "Geneve: Generic Network Virtualization Encapsulation", Internet-Draft draft-ietf-nvo3-geneve-03, September 2016.
[I-D.ietf-nvo3-gue] Herbert, T., Yong, L. and O. Zia, "Generic UDP Encapsulation", Internet-Draft draft-ietf-nvo3-gue-05, October 2016.
[I-D.ietf-nvo3-vxlan-gpe] Maino, F., Kreeger, L. and U. Elzur, "Generic Protocol Extension for VXLAN", Internet-Draft draft-ietf-nvo3-vxlan-gpe-03, October 2016.
[I-D.ietf-sfc-nsh] Quinn, P. and U. Elzur, "Network Service Header", Internet-Draft draft-ietf-sfc-nsh-12, February 2017.
[I-D.ooamdt-rtgwg-ooam-header] Mirsky, G., Nordmark, E., Kumar, N., Kumar, D., Chen, M., Yizhou, L., Mozes, D., Dolson, D. and I. Bagdonas, "OAM Header for use in Overlay Networks", Internet-Draft draft-ooamdt-rtgwg-ooam-header-01, October 2016.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.

7.2. Informative References

[I-D.ietf-mpls-rfc4379bis] Kompella, K., Swallow, G., Pignataro, C., Kumar, N., Aldrin, S. and M. Chen, "Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures", Internet-Draft draft-ietf-mpls-rfc4379bis-09, October 2016.
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, DOI 10.17487/RFC0792, September 1981.
[RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures", RFC 4379, DOI 10.17487/RFC4379, February 2006.
[RFC4443] Conta, A., Deering, S. and M. Gupta, "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", RFC 4443, DOI 10.17487/RFC4443, March 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, DOI 10.17487/RFC5226, May 2008.

Authors' Addresses

Greg Mirsky ZTE Corp. EMail: gregimirsky@gmail.com
Nagendra Kumar Cisco Systems, Inc. EMail: naikumar@cisco.com
Deepak Kumar Cisco Systems, Inc. EMail: dekumar@cisco.com
Mach Chen Huawei Technologies EMail: mach.chen@huawei.com
Yizhou Li Huawei Technologies EMail: liyizhou@huawei.com
David Mozes Mellanox Technologies Ltd. EMail: davidm@mellanox.com
David Dolson Sandvine EMail: ddolson@sandvine.com