Internet-Draft Bitstream EVPN-VPWS October 2023
Gringeri, et al. Expires 25 April 2024 [Page]
Workgroup:
Network Working Group
Internet-Draft:
draft-schmutzer-bess-bitstream-vpws-signalling-00
Published:
Intended Status:
Standards Track
Expires:
Authors:
S. Gringeri
Verizon
J. Whittaker
Verizon
C. Schmutzer, Ed.
Cisco Systems, Inc.
B. Vasudevan
Cisco Systems, Inc.
P. Brissette
Cisco Systems, Inc.

Ethernet VPN Signalling Extensions for Bit-stream VPWS

Abstract

This document specifies the mechanisms to allow for dynamic signalling of Virtual Private Wire Services (VPWS) carrying bit-stream signals over Packet Switched Networks (PSN).

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-Drafts is at https://datatracker.ietf.org/drafts/current/.

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 25 April 2024.

Table of Contents

1. Introduction and Motivation

Virtual Private Wire Service (VPWS) is a widely deployed technology for providing point-to-point (P2P) services for various layer 2 and also layer 1 technologies. Initially VPWS were define in the Pseudowire Emulation Edge-to-Edge (PWE3) architecture [RFC3985] for Frame Relay, ATM, HDLC, PPP, Ethernet, TDM and SONET/SDH.

How Ethernet VPWS can be signalled using Ethernet VPN has already been specified in [RFC8214]. This document is defining necessary signalling extension for Ethernet VPN to also support the following bit stream VPWS instance types:

A generic VPWS reference model similar to the one defined in [RFC3985] and [I-D.ietf-pals-ple] is shown in Figure 1. Data received from a CEs is encapsulated by PEs into the respective VPWS established between the attachment circuits of the local and remote PE and transmitted across the Packet Switched Network (PSN) using a PSN tunnel.

CE1 & CE2 physical                       CE3 & CE4 physical
  interfaces                                interfaces
       |      <------- PSN tunnels ----->      |
       |    +-----------------------------+    |
       |    |                             |    |
+---+  v  +---+                         +---+  v  +---+
|CE1|-----|   |.......... VPWS1 ........|PE2|-----|CE3|
+---+     |   |                         +---+     +---+
          |PE1| packet switched network   |
+----     |   |                         +---+     +---+
|CE2|-----|   |.......... VPWS2 ........|PE3|-----|CE4|
+---+     +---+                         +---+     +---+
          ^ |                             | ^
          | +-----------------------------+ |
          |                                 |
      attachment                       attachment
       circuits                         circuits
          |                                 |
          |<------ emulated services ------>|
Figure 1: VPWS Reference Model

2. Requirements Notation

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 BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

3. Terminology

4. Solution Requirements

To avoid redefining PW types for [RFC8214] the notion of "PW type" from [RFC8077] is maintained and only a new PW type for [I-D.ietf-pals-ple] has been assigned by IANA.

The concept of "CEP type" from [RFC5287] to distinguish different connection types that use the same PW type is adopted. In this document it is referred to as "PLE/CEP type". Two new connection types are defined Section 7.3.

To unambiguously identify the rate of an attachment circuit, also the concept of "CEP/TDM bit-rate" from [RFC5287] is adopted and called "PLE/CEP/TDM bit-rate" herein.

The VPWS signalling requirements are as follows:

5. Service Types

The following sections list all possible service types that are supported by the proposed signalling mechanisms.

5.1. Ethernet Service Types

Table 1: Ethernet Service Types
Service Type Encapsulation Standard PW Type PLE/CEP Type PLE/CEP/TDM Bit-rate
1000Base-X [I-D.ietf-pals-ple] TBD1 0x3 1,250,000
10GBASE-R [I-D.ietf-pals-ple] TBD1 0x3 10,312,500
25GBASE-R [I-D.ietf-pals-ple] TBD1 0x3 25,791,300
40GBASE-R [I-D.ietf-pals-ple] TBD1 0x3 41,250,000
50GBASE-R [I-D.ietf-pals-ple] TBD1 0x3 51,562,500
100GBASE-R [I-D.ietf-pals-ple] TBD1 0x3 103,125,000
200GBASE-R [I-D.ietf-pals-ple] TBD1 0x3 212,500,000
400GBASE-R [I-D.ietf-pals-ple] TBD1 0x3 425,000,000

5.2. Fibre Channel Service Types

Table 2: Fibre Channel Service Types
Service Type Encapsulation Standard PW Type PLE/CEP Type PLE/CEP/TDM Bit-rate
1GFC [I-D.ietf-pals-ple] TBD1 0x3 1,062,500
2GFC [I-D.ietf-pals-ple] TBD1 0x3 2,125,000
4GFC [I-D.ietf-pals-ple] TBD1 0x3 4,250,000
8GFC [I-D.ietf-pals-ple] TBD1 0x3 8,500,000
10GFC [I-D.ietf-pals-ple] TBD1 0x3 10,518,750
16GFC [I-D.ietf-pals-ple] TBD1 0x3 14,025,000
32GFC [I-D.ietf-pals-ple] TBD1 0x3 28,050,000
64GFC [I-D.ietf-pals-ple] TBD1 0x3 57,800,000
128GFC [I-D.ietf-pals-ple] TBD1 0x3 112,200,000

5.3. OTN Service Types

Table 3: OTN Service Types
Service Type Encapsulation Standard PW Type PLE/CEP Type PLE/CEP/TDM Bit-rate
ODU0 [I-D.ietf-pals-ple] TBD1 0x4 1,244,160
ODU1 [I-D.ietf-pals-ple] TBD1 0x4 2,498,775
ODU2 [I-D.ietf-pals-ple] TBD1 0x4 10,037,273
ODU2e [I-D.ietf-pals-ple] TBD1 0x4 10,399,525
ODU3 [I-D.ietf-pals-ple] TBD1 0x4 40,319,218
ODU4 [I-D.ietf-pals-ple] TBD1 0x4 104,794,445

5.4. TDM Service Types

Table 4: TDM Service Types
Service Type Encapsulation Standard PW Type PLE/CEP Type PLE/CEP/TDM Bit-rate
CESoPSN basic mode [RFC5086] 0x0015 N/A N
CESoPSN with CAS [RFC5086] 0x0017 N/A N
E1 [RFC4553] 0x0011 N/A 32
DS1 [RFC4553] 0x0012 N/A 24
DS1 octet-aligned [RFC4553] 0x0012 N/A 25
E3 [RFC4553] 0x0013 N/A 535
T3 [RFC4553] 0x0014 N/A 699

5.5. SONET/SDH Service Types

Table 5: Ethernet Service Types
Service Type Encapsulation Standard PW Type PLE/CEP Type PLE/CEP/TDM Bit-rate
VT1.5/VC-11 [RFC4842] 0x0010 0x1 26
VT2/VC-12 [RFC4842] 0x0010 0x1 35
VT3 [RFC4842] 0x0010 0x1 53
VT6/VC-2 [RFC4842] 0x0010 0x1 107
STS-Nc [RFC4842] 0x0010 0x0 783*N
VC-4-Mc [RFC4842] 0x0010 0x0 7833M
Fract. STS1/VC-3 [RFC4842] 0x0010 0x2 783
Fract. VC-4 [RFC4842] 0x0010 0x2 783*4
Async STS1/VC-3 [RFC4842] 0x0010 0x2 783
OC3/STM1 [I-D.ietf-pals-ple] TBD1 0x3 155,520
OC12/STM4 [I-D.ietf-pals-ple] TBD1 0x3 622,080
OC48/STM16 [I-D.ietf-pals-ple] TBD1 0x3 2,488,320
OC192/STM64 [I-D.ietf-pals-ple] TBD1 0x3 9,953,280
OC768/STM256 [I-D.ietf-pals-ple] TBD1 0x3 39,813,120

6. Reuse of existing BGP EVPN-VPWS Capabilities

A PLE VPWS instance is identified by a pair of per-EVI ethernet A-D routes advertised by two PE nodes establishing the VPWS in accordance to [RFC8214].

The EVPN layer 2 attribute extended community defined in [RFC8214] MUST be supported and added to the per-EVI ethernet A-D route.

7. BGP Bitstream Attribute

To exchange and validate bit-stream specific attachment circuit parameters during the VPWS setup, a new BGP path attribute called "BGP Bitstream attribute" is defined.

The BGP Bitstream attribute defined in this document can be attached to EVPN VPWS routes [RFC8214]. The usage for other Address Family Identifier (AFI) / Subsequent Address Family Identifier (SAFI) combinations is not defined herein but may be specified in future specifications.

The BGP bitstream attribute is an optional and transitive BGP path attribute. The attribute type code TBD2 has been assigned by IANA (see Section 10)

The format is defined as a set of Type/Length/Value (TLV) triplets, described in the following sections and listed in Table 6. This attribute SHOULD only be included with EVPN Network Layer Reachability Information (NLRI).

Table 6: BGP Bitstream attribute TLV
TLV Type Name Length Mandatory
1 PW Type TLV 3 Y
2 PLE/CEP/TDM Bit-rate TLV 5 Y
3 PLE/CEP Options TLV 3 Y 1*
4 TDM Options TLV 13 Y 2*
5 PLE/CEP/TDM Payload Bytes TLV 3 N
6 Endpoint-ID TLV 0..80 N

For a particular PSN it is expected that the network operator will choose a common set of parameters per VPWS type, hence efficient BGP update packing as discussed in Section 12 of [RFC4277] is expected to happen.

7.1. PW Type TLV

The PW Type TLV MUST be present in the BGP bitstream attribute to signal what type of VPWS instance has to be established. Valid PW types for the mechanisms described in this document can be found in Section 5.

The PW Type TLV format is shown in Figure 2

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|      Type     |             Length            |    Reserved   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|           PW Type           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: PW Type TLV

Type : 1

Length : 3

  • The total length in octets of the value portion of the TLV.

Reserved / R :

  • For future use. MUST be set to ZERO and ignored by receiver.

PW Type :

  • A 15-bit quantity containing a value that represents the type of VPWS. Assigned Values are specified in "IANA Allocations for Pseudowire Edge to Edge Emulation (PWE3)" [RFC4446].

7.2. PLE/CEP/TDM Bit-rate TLV

The PLE/CEP/TDM Bit-rate TLV is MANDATORY but MAY be omitted if the attachment circuit type can be unambiguously derived from the PW Type carried in the PW Type TLV. The PLE/CEP/TDM Bit-rate TLV format is shown in Figure 3.

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|      Type     |             Length            |    Reserved   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     PLE/CEP/TDM Bit-rate                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: PLE/CEP/TDM Bit-rate TLV

Type : 2

Length : 5

  • The total length in octets of the value portion of the TLV.

Reserved :

  • 8-bit field for future use. MUST be set to ZERO and ignored by receiver.

PLE/CEP/TDM Bit-rate :

  • A four byte field denoting the desired payload size to be used. Rules defined in [RFC5287] do apply for signalling TDM VPWS. Rules for CEP VPWS are defined in [RFC4842].

    • For PLE [PLE] the bit rate MUST be set to the data rate in units of 1-kbps of the PLE payload.

    • Guidelines for setting the bit rate for SAToP VPWS and CESoP VPWS can be found in [RFC5287]. And for CEP VPWS in [RFC4842].

7.3. PLE/CEP Options TLV

The PLE/CEP Options TLV MUST be present when signalling CEP and PLE VPWS instances. The PLE/CPE Options TLV format is shown in Figure 4.

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|      Type     |             Length            |    Reserved   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        PLE/CEP Options        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: PLE/CEP Options TLV

Type : 3

Length : 3

  • The total length in octets of the value portion of the TLV.

Reserved :

  • 8-bit field for future use. MUST be set to ZERO and ignored by receiver.

PLE/CEP Options :

  • A two byte field with the format as shown in Figure 5

 0                                       1
 0   1   2   3   4   5   6   7   8   9   0   1   2   3   4   5
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|AIS|UNE|RTP|EBM|      Reserved [0:6]       |  PLE/CEP  | Async |
|   |   |   |   |                           |    Type   |T3 |E3 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
Figure 5: PLE/CEP Options

AIS, UNE, RTP, EBM :

  • These bits MUST be set to zero and ignored by the receiver except for CEP VPWS. Guidelines for CEP are defined in [RFC4842]

Reserved :

  • 7-bit field for future use. MUST be set to ZERO and ignored by receiver.

CEP/PLE Type :

  • Indicates the connection type for CEP and PLE. CEP connection types are defined in [RFC4842]. Two new values for PLE are defined in this document:

    • 0x3 - Basic PLE payload

    • 0x4 - Byte aligned PLE payload

Async :

  • These bits MUST be set to zero and ignored by the receiver except for CEP VPWS. Guidelines for CEP are defined in [RFC4842]

7.4. TDM options TLV

Whether when signalling TDM VPWS the TDM Options TLV MUST be present or MAY be omitted when signalling TDM VPWS instances is defined in [RFC5287]. The TDM Options TLV format is shown in Figure 6.

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|      Type     |             Length            |    Reserved   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
+                                                               +
|                         TDM Options                           |
+                                                               +
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: TDM Options TLV

Type : 4

Length : 13

  • The total length in octets of the value portion of the TLV.

Reserved :

  • 8-bit field for future use. MUST be set to ZERO and ignored by receiver.

TDM Options :

  • A twelve byte field with the format as defined in {Section 3.8 of RFC5287}

7.5. PLE/CEP/TDM Payload Bytes TLV

The PLE/CEP/TDM Payload Bytes TLV MAY be included if a non-default payload size is to be used. If this TLV is omitted then the default payload sizes defined in [RFC4553], [RFC5086], [RFC4842] and [PLE] MUST be assumed. The format of the PLE/CEP/TDM Payload Bytes TLV is shown in Figure 7.

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|      Type     |             Length            |    Reserved   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   PLE/CEP/TDM Payload Bytes   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: PLE/CEP/TDM Payload Bytes TLV

Type : 5

Length : 3

  • The total length in octets of the value portion of the TLV.

Reserved :

  • 8-bit field for future use. MUST be set to ZERO and ignored by receiver.

PLE/CEP/TDM Payload Bytes :

  • A two byte field denoting the desired payload size to be used. Rules defined in [RFC5287] do apply for signalling TDM VPWS. Rules for CEP VPWS are defined in [RFC4842].

7.6. Endpoint-ID TLV

The Endpoint-ID TLV MAY be included to allow for misconnection detection. The Endpoint-ID TLV format is shown in Figure 8.

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|      Type     |             Length            |               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               +
//                Endpoint Identifier (variable)               //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Endpoint-ID TLV

Type : 6

Length : 0-80

  • The total length in octets of the value portion of the TLV.

Endpoint Identifier :

  • Arbitrary string of variable length from 0 to 80 octets used to describe the attachment circuit to the remote PE node.

8. Control Plane Operations

The deployment model shown in figure 3 of [RFC8214] does equally apply to the operations defined in this document.

8.1. VPWS Setup and Teardown

After an attachment circuit has been configured to be part of a VPWS instance and has not declared any local defect, the PE node announces his endpoint using a per-EVI ethernet A-D route to other PEs in the PSN via BGP. The Ethernet Tag ID is set to the VPWS instance identifier and the BGP bitstream attribute is included to carry mandatory and optional bit-stream specific attachment circuit parameters.

Both endpoints receiving the EVPN per-EVI A-D route, validate the end to end connectivity by comparing BGP bitstream attributes. Upon successful validation, the VPWS instance comes up and traffic can flow through the PSN. In the scenario where the validation phase fails, the remote PE reachability information is simply ignored and dismissed as a destination candidate. The VPWS instance validation is performed as follow:

  • The mandatory PW type parameter MUST be identical

  • The mandatory PLE/CEP/TDM Bit-rate parameter MUST be identical. This MAY be skipped if this parameter was not signalled because the attachment circuit rate can be unambiguously derived from the PW type [RFC5287].

  • For CEP and PLE, the mandatory CEP/PLE Type parameter signalled via the CEP/PLE Options TLV MUST be identical

  • If the payload size was signalled via the optional PLE/CEP/TDM Payload Bytes TLV it MUST be identical and supported by the PE node. Else the default payload size MUST be assumed.

If any of the previous statements is no true or any of the signal CEP/PLE or TDM options is not supported by the PE node, the VPWS instance must stay down and a appropriate defect MUST be declared.

PLE is structure agnostic for SONET/SDH service types and hence can not validate whether a mix of SONET and SDH attachment circuits are connected (by incident) via VPWS. The detection of such misconfiguration is the responsibility of the operator managing the CE nodes.

In case of multi-homed CEs the mechanisms defined in [RFC8214] apply but are limited to the single-active and port-active scenarios.

Whenever the VPWS instance configuration is removed, the PE node MUST widthdraw its associated per-EVI ethernet A-D route.

8.2. Misconnection Handling

In circuit switched networks it is a common requirement to have the ability to check if the correct two endpoints got connected via a circuit. To confirm that the established bit-stream VPWS service is connecting the appropriate pair of attachment circuits, a Endpoint-ID string MAY be configured on each attachment circuit and communicated to the peer PE node using the Endpoint-ID TLV defined in Section 7.6.

Each endpoint MAY be configured to compare the Endpoint-ID received from the peer PE node to a locally configured expected Endpoint-ID and raise a fault (defect) when the IDs don't match. When a fault is raised, the R bit in the control word must bet set to 1 (backward defect indication) for the VPWS packets sent to the peer PE node. Each endpoint MAY be configured to only compare and report mismatches, but not to raise a fault.

8.3. Failure Scenarios

8.3.1. Single-homed CEs

Whenever a attachment circuit does declare a local fault the following operations MUST happen:

Whenever the CE-bound IWF does enter packet loss state the operations defined in [RFC4553], [RFC5086], [RFC4842] and [I-D.ietf-pals-ple] MUST happen.

8.3.2. Multi-homed CEs

Figure 9 demonstrates a multi-homing scenario. CE1 is connected to PE1 and PE2 where PE1 is the designated forwarder while PE2 is the non designated forwarder.

                    PSN
                 +---------+
    DF  +---+    |         |   +---+   +---+
     +--|PE1|----|---------|---|PE3|---|CE2|
+---+/   +---+    |   VPWS1/|   +---+   +---+
|CE1|             |       / |
+---+\   +---+    |      /  |
     +--|PE2|----|-----+   |
   NDF  +---+    |         |
                 +---------+
Figure 9: EVPN-VPWS Multi-homing Redundancy

In Figure 9 PE1 and PE2 are configured for single-active load-balancing mode. Both PEs are advertising a per-ES ethernet A-D route with the same non-zero Ethernet Segment (ES) value and the single-active bit set. This non-zero ES value is called Ethernet Segment Identifier (ESI).

In this example PE1 is elected as Designated Forwarder (DF) for the shared ESI where as PE2 is the Non-Designated Forwarder (NDF) for that segment. The signalling of primary / backup follows exactly the procedure defined in [RFC8214] where P and B bits of the layer 2 attribute extended community are used to settle proper connectivity.

Upon link failure between CE1 and PE1, PE1 and PE2 follows EVPN Ethernet Segment DF Election procedures described in [RFC8214] and [I-D.ietf-bess-evpn-pref-df] for EVPN-VPWS. PE1 leverage mass-withdraw mechanism to tell PE3 to steer traffic over backup connectivity. The per-EVI ethernet A-D route advertisement remains intact. The main purpose is to keep reachability information available for fast convergence purpose. Therefore, the per-EVI ethernet A-D route MAY be withdrawn only under local fault and MUST be withdraw when the circuit is unconfigured.

Port-active operation happens in the same way as single-active load-balancing mode described before but at the port level instead of being at the sub-interface level.

9. Security Considerations

The same Security Considerations described in [RFC8214] are valid for this document.

10. IANA Considerations

This document defines a new BGP path attribute known as the BGP bitstream attribute. IANA is requested to assign attribute code type TBD2 to the BGP bitstream attribute from the "BGP Path Attributes" registry.

This document defines a new PW Type for PLE VPWS. IANA is requested to assign a PW type value TBD1 from the "MPLS Pseudowire Types" registry.

11. Acknowledgements

to be added

12. References

12.1. Normative References

[I-D.ietf-bess-evpn-pref-df]
Rabadan, J., Sathappan, S., Lin, W., Drake, J., and A. Sajassi, "Preference-based EVPN DF Election", Work in Progress, Internet-Draft, draft-ietf-bess-evpn-pref-df-13, , <https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-pref-df-13>.
[I-D.ietf-pals-ple]
Gringeri, S., Whittaker, J., Leymann, N., Schmutzer, C., and C. Brown, "Private Line Emulation over Packet Switched Networks", Work in Progress, Internet-Draft, draft-ietf-pals-ple-01, , <https://datatracker.ietf.org/doc/html/draft-ietf-pals-ple-01>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC4277]
McPherson, D. and K. Patel, "Experience with the BGP-4 Protocol", RFC 4277, DOI 10.17487/RFC4277, , <https://www.rfc-editor.org/rfc/rfc4277>.
[RFC4553]
Vainshtein, A., Ed. and YJ. Stein, Ed., "Structure-Agnostic Time Division Multiplexing (TDM) over Packet (SAToP)", RFC 4553, DOI 10.17487/RFC4553, , <https://www.rfc-editor.org/rfc/rfc4553>.
[RFC4842]
Malis, A., Pate, P., Cohen, R., Ed., and D. Zelig, "Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) Circuit Emulation over Packet (CEP)", RFC 4842, DOI 10.17487/RFC4842, , <https://www.rfc-editor.org/rfc/rfc4842>.
[RFC5086]
Vainshtein, A., Ed., Sasson, I., Metz, E., Frost, T., and P. Pate, "Structure-Aware Time Division Multiplexed (TDM) Circuit Emulation Service over Packet Switched Network (CESoPSN)", RFC 5086, DOI 10.17487/RFC5086, , <https://www.rfc-editor.org/rfc/rfc5086>.
[RFC5287]
Vainshtein, A. and Y. Stein, "Control Protocol Extensions for the Setup of Time-Division Multiplexing (TDM) Pseudowires in MPLS Networks", RFC 5287, DOI 10.17487/RFC5287, , <https://www.rfc-editor.org/rfc/rfc5287>.
[RFC7432]
Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, , <https://www.rfc-editor.org/rfc/rfc7432>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8214]
Boutros, S., Sajassi, A., Salam, S., Drake, J., and J. Rabadan, "Virtual Private Wire Service Support in Ethernet VPN", RFC 8214, DOI 10.17487/RFC8214, , <https://www.rfc-editor.org/rfc/rfc8214>.
[RFC8986]
Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer, D., Matsushima, S., and Z. Li, "Segment Routing over IPv6 (SRv6) Network Programming", RFC 8986, DOI 10.17487/RFC8986, , <https://www.rfc-editor.org/rfc/rfc8986>.
[RFC9252]
Dawra, G., Ed., Talaulikar, K., Ed., Raszuk, R., Decraene, B., Zhuang, S., and J. Rabadan, "BGP Overlay Services Based on Segment Routing over IPv6 (SRv6)", RFC 9252, DOI 10.17487/RFC9252, , <https://www.rfc-editor.org/rfc/rfc9252>.

12.2. Informative References

[RFC1925]
Callon, R., "The Twelve Networking Truths", RFC 1925, DOI 10.17487/RFC1925, , <https://www.rfc-editor.org/rfc/rfc1925>.
[RFC3985]
Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture", RFC 3985, DOI 10.17487/RFC3985, , <https://www.rfc-editor.org/rfc/rfc3985>.
[RFC8077]
Martini, L., Ed. and G. Heron, Ed., "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", STD 84, RFC 8077, DOI 10.17487/RFC8077, , <https://www.rfc-editor.org/rfc/rfc8077>.

Authors' Addresses

Steven Gringeri
Verizon
United States of America
Jeremy Whittaker
Verizon
United States of America
Christian Schmutzer (editor)
Cisco Systems, Inc.
Austria
Bharath Vasudevan
Cisco Systems, Inc.
Bangalore
India
Patrice Brissette
Cisco Systems, Inc.
Ottawa
Canada