draft-ietf-l2vpn-vpls-bgp-05.txt   draft-ietf-l2vpn-vpls-bgp-06.txt 
Network Working Group K. Kompella, Ed. Network Working Group K. Kompella, Ed.
Internet-Draft Y. Rekhter, Ed. Internet-Draft Y. Rekhter, Ed.
Expires: October 10, 2005 Juniper Networks Expires: July 1, 2006 Juniper Networks
April 8, 2005 December 28, 2005
Virtual Private LAN Service Virtual Private LAN Service
draft-ietf-l2vpn-vpls-bgp-05 draft-ietf-l2vpn-vpls-bgp-06
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2005).
Abstract Abstract
Virtual Private LAN Service (VPLS), also known as Transparent LAN Virtual Private LAN (Local Area Network) Service (VPLS), also known
Service, and Virtual Private Switched Network service, is a useful as Transparent LAN Service, and Virtual Private Switched Network
Service Provider offering. The service offers a Layer 2 Virtual service, is a useful Service Provider offering. The service offers a
Private Network (VPN); however, in the case of VPLS, the customers in Layer 2 Virtual Private Network (VPN); however, in the case of VPLS,
the VPN are connected by a multipoint network, in contrast to the the customers in the VPN are connected by a multipoint Ethernet LAN,
usual Layer 2 VPNs, which are point-to-point in nature. in contrast to the usual Layer 2 VPNs, which are point-to-point in
nature.
This document describes the functions required to offer VPLS, a This document describes the functions required to offer VPLS, a
mechanism for signaling a VPLS, and rules for forwarding VPLS frames mechanism for signaling a VPLS, and rules for forwarding VPLS frames
across a packet switched network. across a packet switched network.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Scope of this Document . . . . . . . . . . . . . . . . . . 3 1.1. Scope of this Document . . . . . . . . . . . . . . . . . . 4
1.2 Conventions used in this document . . . . . . . . . . . . 4 1.2. Conventions used in this document . . . . . . . . . . . . 5
1.3 Changes from version 04 to 05 . . . . . . . . . . . . . . 4 1.3. Changes from version 05 to 06 . . . . . . . . . . . . . . 5
1.4 Changes from version 03 to 04 . . . . . . . . . . . . . . 5 1.4. Changes from version 04 to 05 . . . . . . . . . . . . . . 5
2. Functional Model . . . . . . . . . . . . . . . . . . . . . . . 6 1.5. Changes from version 03 to 04 . . . . . . . . . . . . . . 6
2.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . 6 2. Functional Model . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Assumptions . . . . . . . . . . . . . . . . . . . . . . . 7 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Interactions . . . . . . . . . . . . . . . . . . . . . . . 7 2.2. Assumptions . . . . . . . . . . . . . . . . . . . . . . . 8
3. Control Plane . . . . . . . . . . . . . . . . . . . . . . . . 9 2.3. Interactions . . . . . . . . . . . . . . . . . . . . . . . 8
3.1 Autodiscovery . . . . . . . . . . . . . . . . . . . . . . 9 3. Control Plane . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.1 Functions . . . . . . . . . . . . . . . . . . . . . . 9 3.1. Autodiscovery . . . . . . . . . . . . . . . . . . . . . . 10
3.1.2 Protocol Specification . . . . . . . . . . . . . . . . 10 3.1.1. Functions . . . . . . . . . . . . . . . . . . . . . . 10
3.2 Signaling . . . . . . . . . . . . . . . . . . . . . . . . 10 3.1.2. Protocol Specification . . . . . . . . . . . . . . . . 11
3.2.1 Concepts . . . . . . . . . . . . . . . . . . . . . . . 10 3.2. Signaling . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.2 PW Setup and Teardown . . . . . . . . . . . . . . . . 11 3.2.1. Label Blocks . . . . . . . . . . . . . . . . . . . . . 12
3.2.3 Signaling PE Capabilities . . . . . . . . . . . . . . 12 3.2.2. VPLS BGP NLRI . . . . . . . . . . . . . . . . . . . . 12
3.3 BGP VPLS Operation . . . . . . . . . . . . . . . . . . . . 13 3.2.3. PW Setup and Teardown . . . . . . . . . . . . . . . . 13
3.4 Multi-AS VPLS . . . . . . . . . . . . . . . . . . . . . . 14 3.2.4. Signaling PE Capabilities . . . . . . . . . . . . . . 14
3.4.1 a) VPLS-to-VPLS connections at the AS border 3.3. BGP VPLS Operation . . . . . . . . . . . . . . . . . . . . 15
routers. . . . . . . . . . . . . . . . . . . . . . . . 15 3.4. Multi-AS VPLS . . . . . . . . . . . . . . . . . . . . . . 16
3.4.2 b) EBGP redistribution of VPLS information between 3.4.1. a) VPLS-to-VPLS connections at the ASBRs. . . . . . . 17
ASBRs. . . . . . . . . . . . . . . . . . . . . . . . . 15 3.4.2. b) EBGP redistribution of VPLS information between
3.4.3 c) Multi-hop EBGP redistribution of VPLS ASBRs. . . . . . . . . . . . . . . . . . . . . . . . . 17
information between ASes. . . . . . . . . . . . . . . 16 3.4.3. c) Multi-hop EBGP redistribution of VPLS
3.4.4 Allocation of VE IDs Across Multiple ASes . . . . . . 17 information between ASes. . . . . . . . . . . . . . . 18
3.5 Multi-homing and Path Selection . . . . . . . . . . . . . 17 3.4.4. Allocation of VE IDs Across Multiple ASes . . . . . . 19
4. Data Plane . . . . . . . . . . . . . . . . . . . . . . . . . . 19 3.5. Multi-homing and Path Selection . . . . . . . . . . . . . 19
4.1 Encapsulation . . . . . . . . . . . . . . . . . . . . . . 19 3.6. Hierarchical BGP VPLS . . . . . . . . . . . . . . . . . . 20
4.2 Forwarding . . . . . . . . . . . . . . . . . . . . . . . . 19 4. Data Plane . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.2.1 MAC address learning . . . . . . . . . . . . . . . . . 19 4.1. Encapsulation . . . . . . . . . . . . . . . . . . . . . . 22
4.2.2 Flooding . . . . . . . . . . . . . . . . . . . . . . . 19 4.2. Forwarding . . . . . . . . . . . . . . . . . . . . . . . . 22
4.2.3 "Split Horizon" Forwarding . . . . . . . . . . . . . . 20 4.2.1. MAC address learning . . . . . . . . . . . . . . . . . 22
5. Deployment Options . . . . . . . . . . . . . . . . . . . . . . 21 4.2.2. Aging . . . . . . . . . . . . . . . . . . . . . . . . 23
6. Security Considerations . . . . . . . . . . . . . . . . . . . 22 4.2.3. Flooding . . . . . . . . . . . . . . . . . . . . . . . 23
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 4.2.4. Broadcast and Multicast . . . . . . . . . . . . . . . 23
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.2.5. "Split Horizon" Forwarding . . . . . . . . . . . . . . 24
8.1 Normative References . . . . . . . . . . . . . . . . . . . 24 4.2.6. Qualified and Unqualified Learning . . . . . . . . . . 24
8.2 Informative References . . . . . . . . . . . . . . . . . . 24 4.2.7. Class of Service . . . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 25 5. Deployment Options . . . . . . . . . . . . . . . . . . . . . . 26
A. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 26 6. Security Considerations . . . . . . . . . . . . . . . . . . . 27
B. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 27 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
Intellectual Property and Copyright Statements . . . . . . . . 28 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.1. Normative References . . . . . . . . . . . . . . . . . . . 29
8.2. Informative References . . . . . . . . . . . . . . . . . . 29
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 31
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 32
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 33
Intellectual Property and Copyright Statements . . . . . . . . . . 34
1. Introduction 1. Introduction
Virtual Private LAN Service (VPLS), also known as Transparent LAN Virtual Private LAN Service (VPLS), also known as Transparent LAN
Service, and Virtual Private Switched Network service, is a useful Service, and Virtual Private Switched Network service, is a useful
service offering. A Virtual Private LAN appears in (almost) all service offering. A Virtual Private LAN appears in (almost) all
respects as a LAN to customers of a Service Provider. However, in a respects as an Ethernet LAN to customers of a Service Provider.
VPLS, the customers are not all connected to a single LAN; the However, in a VPLS, the customers are not all connected to a single
customers may be spread across a metro or wide area. In essence, a LAN; the customers may be spread across a metro or wide area. In
VPLS glues several individual LANs across a packet-switched network essence, a VPLS glues together several individual LANs across a
to appear and function as a single LAN ([6]). packet-switched network to appear and function as a single LAN ([7]).
This is accomplished by incorporating MAC address learning, flooding
and forwarding functions in the context of pseudowires that connect
these individual LANs across the packet-switched network.
This document describes the functions needed to offer VPLS, and goes This document details the functions needed to offer VPLS, and then
on to describe a mechanism for signaling a VPLS, as well as a goes on to describe a mechanism for the autodiscovery of the
mechanism for transport of VPLS frames over tunnels across a packet endpoints of a VPLS as well as for signaling a VPLS. It also
switched network. The signaling mechanism uses BGP as the control describes how VPLS frames are transported over tunnels across a
plane protocol. This document also briefly discusses deployment packet switched network. The autodiscovery and signaling mechanism
options, in particular, the notion of decoupling functions across uses BGP as the control plane protocol. This document also briefly
devices. discusses deployment options, in particular, the notion of decoupling
functions across devices.
Alternative approaches include: [11], which allows one to build a Alternative approaches include: [13], which allows one to build a
Layer 2 VPN with Ethernet as the interconnect; and [10]), which Layer 2 VPN with Ethernet as the interconnect; and [12]), which
allows one to set up an Ethernet connection across a packet-switched allows one to set up an Ethernet connection across a packet-switched
network. Both of these, however, offer point-to-point Ethernet network. Both of these, however, offer point-to-point Ethernet
services. What distinguishes VPLS from the above two is that a VPLS services. What distinguishes VPLS from the above two is that a VPLS
offers a multipoint service. A mechanism for setting up pseudowires offers a multipoint service. A mechanism for setting up pseudowires
for VPLS using the Label Distribution Protocol (LDP) is defined in for VPLS using the Label Distribution Protocol (LDP) is defined in
[7]. [8].
1.1 Scope of this Document 1.1. Scope of this Document
This document has four major parts: defining a VPLS functional model; This document has four major parts: defining a VPLS functional model;
defining a control plane for setting up VPLS; defining the data plane defining a control plane for setting up VPLS; defining the data plane
for VPLS (encapsulation and forwarding of data); and defining various for VPLS (encapsulation and forwarding of data); and defining various
deployment options. deployment options.
The functional model underlying VPLS is laid out in Section 2. This The functional model underlying VPLS is laid out in Section 2. This
describes the service being offered, the network components that describes the service being offered, the network components that
interact to provide the service, and at a high level their interact to provide the service, and at a high level their
interactions. interactions.
The control plane described in this document uses Multiprotocol BGP The control plane described in this document uses Multiprotocol BGP
[3] to establish VPLS service, i.e., for the autodiscovery of VPLS [3] to establish VPLS service, i.e., for the autodiscovery of VPLS
members and for the setup and teardown of the pseudowires that members and for the setup and teardown of the pseudowires that
constitute a given VPLS instance. Section 3 focuses on this, and constitute a given VPLS instance. Section 3 focuses on this, and
also describes how a VPLS that spans Autonomous System boundaries is also describes how a VPLS that spans Autonomous System boundaries is
set up, as well as how multi-homing is handled. Using BGP as the set up, as well as how multi-homing is handled. Using BGP as the
control plane for VPNs is not new (see [11], [9] and [8]): what is control plane for VPNs is not new (see [13], [10] and [9]): what is
described here is based on the mechanisms proposed in [9]. described here is based on the mechanisms proposed in [10].
The forwarding plane and the actions that a participating PE must The forwarding plane and the actions that a participating Provider
take is described in Section 4. Edge (PE) router offering the VPLS service must take is described in
Section 4.
In Section 5, the notion of 'decoupled' operation is defined, and the In Section 5, the notion of 'decoupled' operation is defined, and the
interaction of decoupled and non-decoupled PEs is described. interaction of decoupled and non-decoupled PEs is described.
Decoupling allows for more flexible deployment of VPLS. Decoupling allows for more flexible deployment of VPLS.
1.2 Conventions used in this document 1.2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 ([1]). document are to be interpreted as described in RFC 2119 ([1]).
1.3 Changes from version 04 to 05 1.3. Changes from version 05 to 06
[NOTE to RFC Editor: this section is to be removed before [NOTE to RFC Editor: this section is to be removed before
publication.] publication.]
Updated IANA section to reflect agreement with authors of [8] that Changes in response to GenART review.
Updated Abstract and Introduction to make it clear that VPLS is an
Ethernet-based service.
Added sections on Aging, Broadcast and Multicast, Qualified and
Unqualified learning and CoS. Also added a section on scaling the
BGP control plane. These were requested for consistency between the
BGP and LDP VPLS documents.
Added a section clarifying the concepts of label blocks, why they are
necessary and how they are used.
For multi-AS operation, added a short introduction to the three
options, comparing their usage.
Lots of clean-up: consistent usage of terms, expansion of acronyms
before use, references.
1.4. Changes from version 04 to 05
[NOTE to RFC Editor: this section is to be removed before
publication.]
Updated IANA section to reflect agreement with authors of [9] that
the two docs should use the same AFI for L2VPN information. the two docs should use the same AFI for L2VPN information.
Addressed comments received from Alex Zinin. No technical changes, Addressed comments received from Alex Zinin. No technical changes,
but a more complete description to cover the issues that Alex raised: but a more complete description to cover the issues that Alex raised:
1. encoding of BGP NEXT_HOP for the new AFI/SAFI is not described 1. encoding of BGP NEXT_HOP for the new AFI/SAFI is not described
2. VE ID, Block offset, Block size, Label base are not described 2. VE ID, Block offset, Block size, Label base are not described
anywhere anywhere
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Changes to address these: Changes to address these:
1. Broke up section 3.2.1 into "Concepts" and "PW Setup". 1. Broke up section 3.2.1 into "Concepts" and "PW Setup".
2. Expanded section on "Signaling PE Capabilities". 2. Expanded section on "Signaling PE Capabilities".
3. Added a new section 3.3 "BGP VPLS Operation". 3. Added a new section 3.3 "BGP VPLS Operation".
4. Minor tweaking, e.g. to fix section number references. 4. Minor tweaking, e.g. to fix section number references.
1.4 Changes from version 03 to 04 1.5. Changes from version 03 to 04
[NOTE to RFC Editor: this section is to be removed before [NOTE to RFC Editor: this section is to be removed before
publication.] publication.]
Incorporated IDR review comments from Eric Ji, Chaitanya Kodeboyina, Incorporated IDR review comments from Eric Ji, Chaitanya Kodeboyina,
and Mike Loomis. Most changes are clarifications and rewording for and Mike Loomis. Most changes are clarifications and rewording for
better readability. The substantive changes are to remove several better readability. The substantive changes are to remove several
flags from the control field. flags from the control field.
2. Functional Model 2. Functional Model
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|u-PE|--PE3 / \ / |u-PE|--PE3 / \ /
|----| -------- ------- |----| -------- -------
---- / | ---- ---- / | ----
/ \/ \ / \ CE = Customer Edge Device / \/ \ / \ CE = Customer Edge Device
| A3 CE3 --CE4 A4 | PE = Provider Edge Router | A3 CE3 --CE4 A4 | PE = Provider Edge Router
\ / \ / u-PE = Layer 2 Aggregation \ / \ / u-PE = Layer 2 Aggregation
---- ---- A<n> = Customer site n ---- ---- A<n> = Customer site n
Figure 1: Example of a VPLS Figure 1: Example of a VPLS
2.1 Terminology 2.1. Terminology
Terminology similar to that in [9] is used, with the addition of Terminology similar to that in [10] is used: a Service Provider (SP)
"u-PE", a Layer 2 PE device used for Layer 2 aggregation. The notion network with P (Provider-only) and PE (Provider Edge) routers, and
of u-PE is described further in Section 5. PE and u-PE devices are customers with CE (Customer Edge) devices. Here, however, there is
"VPLS-aware", which means that they know that a VPLS service is being an additional concept, that of a "u-PE", a Layer 2 PE device used for
offered. We will call these VPLS edge devices, which could be either Layer 2 aggregation. The notion of u-PE is described further in
a PE or an u-PE, a VE. Section 5. PE and u-PE devices are "VPLS-aware", which means that
they know that a VPLS service is being offered. We will call these
VPLS edge devices, which could be either a PE or an u-PE, a VE.
In contrast, the CE device (which may be owned and operated by either In contrast, the CE device (which may be owned and operated by either
the SP or the customer) is VPLS-unaware; as far as the CE is the SP or the customer) is VPLS-unaware; as far as the CE is
concerned, it is connected to the other CEs in the VPLS via a Layer 2 concerned, it is connected to the other CEs in the VPLS via a Layer 2
switched network. This means that there should be no changes to a CE switched network. This means that there should be no changes to a CE
device, either to the hardware or the software, in order to offer device, either to the hardware or the software, in order to offer
VPLS. VPLS.
A CE device may be connected to a PE or a u-PE via Layer 2 switches A CE device may be connected to a PE or a u-PE via Layer 2 switches
that are VPLS-unaware. From a VPLS point of view, such Layer 2 that are VPLS-unaware. From a VPLS point of view, such Layer 2
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The term "demultiplexor" refers to an identifier in a data packet The term "demultiplexor" refers to an identifier in a data packet
that identifies both the VPLS to which the packet belongs as well as that identifies both the VPLS to which the packet belongs as well as
the ingress PE. In this document, the demultiplexor is an MPLS the ingress PE. In this document, the demultiplexor is an MPLS
label. label.
The term "VPLS" will refer to the service as well as a particular The term "VPLS" will refer to the service as well as a particular
instantiation of the service (i.e., an emulated LAN); it should be instantiation of the service (i.e., an emulated LAN); it should be
clear from the context which usage is intended. clear from the context which usage is intended.
2.2 Assumptions 2.2. Assumptions
The Service Provider Network is a packet switched network. The PEs The Service Provider Network is a packet switched network. The PEs
are assumed to be (logically) full-meshed with tunnels over which are assumed to be (logically) fully meshed with tunnels over which
packets that belong to a service (such as VPLS) are encapsulated and packets that belong to a service (such as VPLS) are encapsulated and
forwarded. These tunnels can be IP tunnels, such as GRE, or MPLS forwarded. These tunnels can be IP tunnels, such as GRE, or MPLS
tunnels, established by RSVP-TE or LDP. These tunnels are tunnels, established by RSVP-TE or LDP. These tunnels are
established independently of the services offered over them; the established independently of the services offered over them; the
signaling and establishment of these tunnels are not discussed in signaling and establishment of these tunnels are not discussed in
this document. this document.
"Flooding" and MAC address "learning" (see Section 4) are an integral "Flooding" and MAC address "learning" (see Section 4) are an integral
part of VPLS. However, these activities are private to an SP device, part of VPLS. However, these activities are private to an SP device,
i.e., in the VPLS described below, no SP device requests another SP i.e., in the VPLS described below, no SP device requests another SP
device to flood packets or learn MAC addresses on its behalf. device to flood packets or learn MAC addresses on its behalf.
All the PEs participating in a VPLS are assumed to be fully meshed, All the PEs participating in a VPLS are assumed to be fully meshed in
i.e., every (ingress) PE can send a VPLS packet to the egress PE(s) the data plane, i.e., there is a bidirectional pseudowire between
directly, without the need for an intermediate PE (see every pair of PEs participating in that VPLS, and thus every
Section 4.2.3.) (ingress) PE can send a VPLS packet to the egress PE(s) directly,
without the need for an intermediate PE (see Section 4.2.5.) This
requires that VPLS PEs are logically fully meshed in the control
plane so that a PE can send a message to another PE to set up the
necessary pseudowires. See Section 3.6 for a discussion on
alternatives to achieve a logical full mesh in the control plane.
2.3 Interactions 2.3. Interactions
VPLS is a "LAN Service" in that CE devices that belong to VPLS V can VPLS is a "LAN Service" in that CE devices that belong to VPLS V can
interact through the SP network as if they were connected by a LAN. interact through the SP network as if they were connected by a LAN.
VPLS is "private" in that CE devices that belong to different VPLSs VPLS is "private" in that CE devices that belong to different VPLSs
cannot interact. VPLS is "virtual" in that multiple VPLSs can be cannot interact. VPLS is "virtual" in that multiple VPLSs can be
offered over a common packet switched network. offered over a common packet switched network.
PE devices interact to "discover" all the other PEs participating in PE devices interact to "discover" all the other PEs participating in
the same VPLS, and to exchange demultiplexors. These interactions the same VPLS, and to exchange demultiplexors. These interactions
are control-driven, not data-driven. are control-driven, not data-driven.
u-PEs interact with PEs to establish connections with remote PEs or u-PEs interact with PEs to establish connections with remote PEs or
u-PEs in the same VPLS. This interaction is control-driven. u-PEs in the same VPLS. This interaction is control-driven.
PE devices can participate simultaneously in both VPLS and IP VPNs PE devices can participate simultaneously in both VPLS and IP VPNs
([9]). These are independent services, and the information exchanged ([10]). These are independent services, and the information
for each type of service is kept separate as the Network Layer exchanged for each type of service is kept separate as the Network
Reachability Information (NLRI) used for this exchange have different Layer Reachability Information (NLRI) used for this exchange have
Address Family Identifiers (AFI) and Subsequent Address Family different Address Family Identifiers (AFI) and Subsequent Address
Identifiers (SAFI). Consequently, an implementation MUST maintain a Family Identifiers (SAFI). Consequently, an implementation MUST
separate routing storage for each service. However, multiple maintain a separate routing storage for each service. However,
services can use the same underlying tunnels; the VPLS or VPN label multiple services can use the same underlying tunnels; the VPLS or
is used to demultiplex the packets belonging to different services. VPN label is used to demultiplex the packets belonging to different
services.
3. Control Plane 3. Control Plane
There are two primary functions of the VPLS control plane: There are two primary functions of the VPLS control plane:
autodiscovery, and setup and teardown of the pseudowires that autodiscovery, and setup and teardown of the pseudowires that
constitute the VPLS, often called signaling. Section 3.1 and constitute the VPLS, often called signaling. Section 3.1 and
Section 3.2 describe these functions. Both of these functions are Section 3.2 describe these functions. Both of these functions are
accomplished with a single BGP Update advertisement; Section 3.3 accomplished with a single BGP Update advertisement; Section 3.3
describes how this is done by detailing BGP protocol operation for describes how this is done by detailing BGP protocol operation for
VPLS. Section 3.4 describes the setting up of pseudowires that span VPLS. Section 3.4 describes the setting up of pseudowires that span
Autonomous Systems. Section 3.5 describes how multi-homing is Autonomous Systems. Section 3.5 describes how multi-homing is
handled. handled.
3.1 Autodiscovery 3.1. Autodiscovery
Discovery refers to the process of finding all the PEs that Discovery refers to the process of finding all the PEs that
participate in a given VPLS. A PE can either be configured with the participate in a given VPLS instance. A PE can either be configured
identities of all the other PEs in a given VPLS, or the PE can use with the identities of all the other PEs in a given VPLS, or the PE
some protocol to discover the other PEs. The latter is called can use some protocol to discover the other PEs. The latter is
autodiscovery. called autodiscovery.
The former approach is fairly configuration-intensive, especially The former approach is fairly configuration-intensive, especially
since it is required that the PEs participating in a given VPLS are since it is required that the PEs participating in a given VPLS are
fully meshed (i.e., that every PE in a given VPLS establish fully meshed (i.e., that every PE in a given VPLS establish
pseudowires to every other PE in that VPLS). Furthermore, when the pseudowires to every other PE in that VPLS). Furthermore, when the
topology of a VPLS changes (i.e., a PE is added to, or removed from topology of a VPLS changes (i.e., a PE is added to, or removed from
the VPLS), the VPLS configuration on all PEs in that VPLS must be the VPLS), the VPLS configuration on all PEs in that VPLS must be
changed. changed.
In the autodiscovery approach, each PE "discovers" which other PEs In the autodiscovery approach, each PE "discovers" which other PEs
are part of a given VPLS by means of some protocol, in this case BGP. are part of a given VPLS by means of some protocol, in this case BGP.
This allows each PE's configuration to consist only of the identity This allows each PE's configuration to consist only of the identity
of the VPLS instance established on this PE, not the identity of of the VPLS instance established on this PE, not the identity of
every other PE in that VPLS instance -- that is auto-discovered. every other PE in that VPLS instance -- that is auto-discovered.
Moreover, when the topology of a VPLS changes, only the affected PE's Moreover, when the topology of a VPLS changes, only the affected PE's
configuration changes; other PEs automatically find out about the configuration changes; other PEs automatically find out about the
change and adapt. change and adapt.
3.1.1 Functions 3.1.1. Functions
A PE that participates in a given VPLS V must be able to tell all A PE that participates in a given VPLS instance V must be able to
other PEs in VPLS V that it is also a member of V. A PE must also tell all other PEs in VPLS V that it is also a member of V. A PE must
have a means of declaring that it no longer participates in a VPLS. also have a means of declaring that it no longer participates in a
To do both of these, the PE must have a means of identifying a VPLS VPLS. To do both of these, the PE must have a means of identifying a
and a means by which to communicate to all other PEs. VPLS and a means by which to communicate to all other PEs.
U-PE devices also need to know what constitutes a given VPLS; U-PE devices also need to know what constitutes a given VPLS;
however, they don't need the same level of detail. The PE (or PEs) however, they don't need the same level of detail. The PE (or PEs)
to which a u-PE is connected gives the u-PE an abstraction of the to which a u-PE is connected gives the u-PE an abstraction of the
VPLS; this is described in section 5. VPLS; this is described in section 5.
3.1.2 Protocol Specification 3.1.2. Protocol Specification
The specific mechanism for autodiscovery described here is based on The specific mechanism for autodiscovery described here is based on
[11] and [9]; it uses BGP extended communities [4] to identify [13] and [10]; it uses BGP extended communities [4] to identify
members of a VPLS. A more generic autodiscovery mechanism is members of a VPLS, in particular, the Route Target community, whose
described in [8]. The specific extended community used is the Route format is described in [4]. The semantics of the use of Route
Target, whose format is described in [4]. The semantics of the use Targets is described in [10]; their use in VPLS is identical.
of Route Targets is described in [9]; their use in VPLS is identical.
As it has been assumed that VPLSs are fully meshed, a single Route As it has been assumed that VPLSs are fully meshed, a single Route
Target RT suffices for a given VPLS V, and in effect that RT is the Target RT suffices for a given VPLS V, and in effect that RT is the
identifier for VPLS V. identifier for VPLS V.
A PE announces (typically via I-BGP) that it belongs to VPLS V by A PE announces (typically via I-BGP) that it belongs to VPLS V by
annotating its NLRIs for V (see next subsection) with Route Target annotating its NLRIs for V (see next subsection) with Route Target
RT, and acts on this by accepting NLRIs from other PEs that have RT, and acts on this by accepting NLRIs from other PEs that have
Route Target RT. A PE announces that it no longer participates in V Route Target RT. A PE announces that it no longer participates in V
by withdrawing all NLRIs that it had advertised with Route Target RT. by withdrawing all NLRIs that it had advertised with Route Target RT.
3.2 Signaling 3.2. Signaling
Once discovery is done, each pair of PEs in a VPLS must be able to Once discovery is done, each pair of PEs in a VPLS must be able to
establish (and tear down) pseudowires to each other, i.e., exchange establish (and tear down) pseudowires to each other, i.e., exchange
(and withdraw) demultiplexors. This process is known as signaling. (and withdraw) demultiplexors. This process is known as signaling.
Signaling is also used to transmit certain characteristics of the Signaling is also used to transmit certain characteristics of the
pseudowires that a PE sets up for a given VPLS. pseudowires that a PE sets up for a given VPLS.
Recall that a demultiplexor is used to distinguish among several Recall that a demultiplexor is used to distinguish among several
different streams of traffic carried over a tunnel, each stream different streams of traffic carried over a tunnel, each stream
possibly representing a different service. In the case of VPLS, the possibly representing a different service. In the case of VPLS, the
demultiplexor not only says to which specific VPLS a packet belongs, demultiplexor not only says to which specific VPLS a packet belongs,
but also identifies the ingress PE. The former information is used but also identifies the ingress PE. The former information is used
for forwarding the packet; the latter information is used for for forwarding the packet; the latter information is used for
learning MAC addresses. The demultiplexor described here is an MPLS learning MAC addresses. The demultiplexor described here is an MPLS
label. However, note that the PE-to-PE tunnels need not be MPLS label. However, note that the PE-to-PE tunnels need not be MPLS
tunnels. tunnels.
3.2.1 Concepts Using a distinct BGP Update message to send a demultiplexor to each
remote PE would require the originating PE to send N such messages
for N remote PEs. The solution described in this document allows a
PE to send a single (common) Update message that contains
demultiplexors for all the remote PEs, instead of N individual
messages. Doing this reduces the control plane load both on the
originating PE as well as on the BGP Route Reflectors that may be
involved in distributing this Update to other PEs.
3.2.1. Label Blocks
To accomplish this, we introduce the notion of "label blocks". A
label block, defined by a label base LB and a VE block size VBS, is a
contiguous set of labels {LB, LB+1, ..., LB+VBS-1}. Here's how label
blocks work. All PEs within a given VPLS are assigned unique VE IDs
as part of their configuration. A PE X wishing to send a VPLS update
sends the same label block information to all other PEs. Each
receiving PE infers the label intended for PE X by adding their
(unique) VE ID to the label base. In this manner, each receiving PE
gets a unique demultiplexor for PE X for that VPLS.
This simple notion is enhanced with the concept of a VE block offset
VBO. A label block defined by <LB, VBO, VBS> is the set {LB+VBO, LB+
VBO+1, ..., LB+VBO+VBS-1}. Thus, instead of a single large label
block to cover all VE IDs in a VPLS, one can have several label
blocks, each with a different label base. This makes label block
management easier, and also allows PE X to cater gracefully to a PE
joining a VPLS with a VE ID that is not covered by the set of label
blocks that that PE X has already advertised.
When a PE starts up, or is configured with a new VPLS instance, the
BGP process may wish to wait to receive several advertisements for
that VPLS instance from other PEs to improve the efficiency of label
block allocation.
3.2.2. VPLS BGP NLRI
The VPLS BGP NLRI described below, with a new AFI and SAFI (see [3]) The VPLS BGP NLRI described below, with a new AFI and SAFI (see [3])
is used to exchange VPLS membership and demultiplexors. is used to exchange VPLS membership and demultiplexors.
A VPLS BGP NLRI has the following information elements: a VE ID, a VE A VPLS BGP NLRI has the following information elements: a VE ID, a VE
Block Offset, a VE Block Size and a label base. The exact format is Block Offset, a VE Block Size and a label base. The format of the
given below. VPLS NLRI is given below. The AFI is the L2VPN AFI (to be assigned
by IANA), and the SAFI is the VPLS SAFI (65). The Length field is in
octets.
+------------------------------------+
| Length (2 octets) |
+------------------------------------+
| Route Distinguisher (8 octets) |
+------------------------------------+
| VE ID (2 octets) |
+------------------------------------+
| VE Block Offset (2 octets) |
+------------------------------------+
| VE Block Size (2 octets) |
+------------------------------------+
| Label Base (3 octets) |
+------------------------------------+
Figure 2: BGP NLRI for VPLS Information
A PE participating in a VPLS must have at least one VE ID. If the PE A PE participating in a VPLS must have at least one VE ID. If the PE
is the VE, it typically has one VE ID. If the PE is connected to is the VE, it typically has one VE ID. If the PE is connected to
several u-PEs, it has a distinct VE ID for each u-PE. It may several u-PEs, it has a distinct VE ID for each u-PE. It may
additionally have a VE ID for itself, if it itself acts as a VE for additionally have a VE ID for itself, if it itself acts as a VE for
that VPLS. In what follows, we will call the PE announcing the VPLS that VPLS. In what follows, we will call the PE announcing the VPLS
NLRI PE-a, and we will assume that PE-a owns VE ID V (either NLRI PE-a, and we will assume that PE-a owns VE ID V (either
belonging to PE-a itself, or to a u-PE connected to PE-a). belonging to PE-a itself, or to a u-PE connected to PE-a).
VE IDs are typically assigned by the network administrator. Their VE IDs are typically assigned by the network administrator. Their
scope is local to a VPLS. A given VE ID should belong to only one scope is local to a VPLS. A given VE ID should belong to only one
PE, unless a CE is multi-homed (see Section 3.5). PE, unless a CE is multi-homed (see Section 3.5).
A label block is a set of demultiplexor labels used to reach a given A label block is a set of demultiplexor labels used to reach a given
VE ID. A VPLS BGP NLRI with VE ID V, VE Block Offset VBO, VE Block VE ID. A VPLS BGP NLRI with VE ID V, VE Block Offset VBO, VE Block
Size VBS and label base LB implicitly announces Size VBS and label base LB communicates to its peers the following:
label block for V: labels from LB to (LB + VBS - 1), and label block for V: labels from LB to (LB + VBS - 1), and
remote VE set for V: from VBO to (VBO + VBS - 1). remote VE set for V: from VBO to (VBO + VBS - 1).
There is a one-to-one correspondance between the remote VE set and There is a one-to-one correspondence between the remote VE set and
the label block: VE ID (VBO + n) corresponds to label (LB + n). the label block: VE ID (VBO + n) corresponds to label (LB + n).
3.2.2 PW Setup and Teardown 3.2.3. PW Setup and Teardown
Suppose PE-a is part of VPLS foo, and makes an announcement with VE Suppose PE-a is part of VPLS foo, and makes an announcement with VE
ID V, VE Block Offset VBO, VE Block Size VBS and label base LB. If ID V, VE Block Offset VBO, VE Block Size VBS and label base LB. If
PE-b is also part of VPLS foo, and has VE ID W, PE-b does the PE-b is also part of VPLS foo, and has VE ID W, PE-b does the
following: following:
1. is W part of PE-a's 'remote VE set': if VBO <= W < VBO + VBS, 1. checks if W is part of PE-a's 'remote VE set': if VBO <= W < VBO
then W is part of PE-a's remote VE set. If not, PE-b ignores + VBS, then W is part of PE-a's remote VE set. If not, PE-b
this message, and skips the rest of this procedure. ignores this message, and skips the rest of this procedure.
2. set up a PW to PE-a: the demultiplexor label to send traffic from 2. sets up a PW to PE-a: the demultiplexor label to send traffic
PE-b to PE-a is computed as (LB + W - VBO). from PE-b to PE-a is computed as (LB + W - VBO).
3. is V part of any 'remote VE set' that PE-b announced: PE-b checks 3. checks if V is part of any 'remote VE set' that PE-b announced,
if V belongs to some remote VE set that PE-b announced, say with i.e., PE-b checks if V belongs to some remote VE set that PE-b
VE Block Offset VBO', VE Block Size VBS' and label base LB'. If announced, say with VE Block Offset VBO', VE Block Size VBS' and
not, PE-b MUST make a new announcement as described in label base LB'. If not, PE-b MUST make a new announcement as
Section 3.3. described in Section 3.3.
4. set up a PW from PE-a: the demultiplexor label over which PE-b 4. sets up a PW from PE-a: the demultiplexor label over which PE-b
should expect traffic from PE-a is computed as: (LB' + V - VBO'). should expect traffic from PE-a is computed as: (LB' + V - VBO').
If Y withdraws an NLRI for V that X was using, then X MUST tear down If Y withdraws an NLRI for V that X was using, then X MUST tear down
its ends of the pseudowire between X and Y. its ends of the pseudowire between X and Y.
The format of the VPLS NLRI is given below. The AFI is the L2VPN AFI 3.2.4. Signaling PE Capabilities
(to be assigned by IANA), and the SAFI is the VPLS SAFI (65).
+------------------------------------+
| Length (2 octets) |
+------------------------------------+
| Route Distinguisher (8 octets) |
+------------------------------------+
| VE ID (2 octets) |
+------------------------------------+
| VE Block Offset (2 octets) |
+------------------------------------+
| VE Block Size (2 octets) |
+------------------------------------+
| Label Base (3 octets) |
+------------------------------------+
Figure 2: BGP NLRI for VPLS Information
3.2.3 Signaling PE Capabilities
The following extended attribute, the "Layer2 Info Extended The following extended attribute, the "Layer2 Info Extended
Community", is used to signal control information about the Community", is used to signal control information about the
pseudowires to be setup for a given VPLS. This information includes pseudowires to be setup for a given VPLS. This information includes
the Encaps Type (type of encapsulation on the pseudowires), Control the Encaps Type (type of encapsulation on the pseudowires), Control
Flags (control information regarding the pseudowires) and the Maximum Flags (control information regarding the pseudowires) and the Maximum
Transmission Unit (MTU) to be used on the pseudowires. Transmission Unit (MTU) to be used on the pseudowires.
The Encaps Type for VPLS is 19. The Encaps Type for VPLS is 19.
skipping to change at page 13, line 4 skipping to change at page 14, line 45
| Encaps Type (1 octet) | | Encaps Type (1 octet) |
+------------------------------------+ +------------------------------------+
| Control Flags (1 octet) | | Control Flags (1 octet) |
+------------------------------------+ +------------------------------------+
| Layer-2 MTU (2 octet) | | Layer-2 MTU (2 octet) |
+------------------------------------+ +------------------------------------+
| Reserved (2 octets) | | Reserved (2 octets) |
+------------------------------------+ +------------------------------------+
Figure 3: Layer2 Info Extended Community Figure 3: Layer2 Info Extended Community
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| MBZ |C|S| (MBZ = MUST Be Zero) | MBZ |C|S| (MBZ = MUST Be Zero)
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 4: Control Flags Bit Vector Figure 4: Control Flags Bit Vector
With reference to Figure 4, the following bits in the Control Flags With reference to Figure 4, the following bits in the Control Flags
are defined; the remaining bits, designated MBZ, MUST be set to zero are defined; the remaining bits, designated MBZ, MUST be set to zero
when sending and MUST be ignored when receiving this community. when sending and MUST be ignored when receiving this community.
Name Meaning Name Meaning
C If set to 1 (0), Control word MUST (NOT) be present when C A Control word ([5]) MUST or MUST NOT be present when
sending VPLS packets to this PE [10]. sending VPLS packets to this PE, depending on whether C
S If set to 1 (0), Sequenced delivery of frames is (not) is 1 or 0, respectively
required when sending VPLS packets to this PE. S Sequenced delivery of frames MUST or MUST NOT be used
when sending VPLS packets to this PE. depending on
whether S is 1 or 0, respectively
3.3 BGP VPLS Operation 3.3. BGP VPLS Operation
To create a new VPLS, say VPLS foo, a network administrator must pick To create a new VPLS, say VPLS foo, a network administrator must pick
a RT for VPLS foo, say RT-foo. This will be used by all PEs that a RT for VPLS foo, say RT-foo. This will be used by all PEs that
serve VPLS foo. To configure a given PE, say PE-a, to be part of serve VPLS foo. To configure a given PE, say PE-a, to be part of
VPLS foo, the network administrator only has to choose a VE ID V for VPLS foo, the network administrator only has to choose a VE ID V for
PE-a. (If PE-a is connected to u-PEs, PE-a may be configured with PE-a. (If PE-a is connected to u-PEs, PE-a may be configured with
more than one VE ID; in that case, the following is done for each VE more than one VE ID; in that case, the following is done for each VE
ID). The PE may also be configured with a Route Distinguisher (RD); ID). The PE may also be configured with a Route Distinguisher (RD);
if not, it generates a unique RD for VPLS foo. Say the RD is if not, it generates a unique RD for VPLS foo. Say the RD is
RD-foo-a. PE-a then generates an initial label block and a remote VE RD-foo-a. PE-a then generates an initial label block and a remote VE
skipping to change at page 13, line 48 skipping to change at page 15, line 45
the BGP Next Hop for this NLRI as itself, and announces this NLRI to the BGP Next Hop for this NLRI as itself, and announces this NLRI to
its peers. The Network Layer protocol associated with the Network its peers. The Network Layer protocol associated with the Network
Address of the Next Hop for the combination <AFI=L2VPN AFI, SAFI=VPLS Address of the Next Hop for the combination <AFI=L2VPN AFI, SAFI=VPLS
SAFI> is IP; this association is required by [3], Section 5. If the SAFI> is IP; this association is required by [3], Section 5. If the
value of the Length of the Next Hop field is 4, then the Next Hop value of the Length of the Next Hop field is 4, then the Next Hop
contains an IPv4 address. If this value is 16, then the Next Hop contains an IPv4 address. If this value is 16, then the Next Hop
contains an IPv6 address. contains an IPv6 address.
If PE-a hears from another PE, say PE-b, a VPLS BGP announcement with If PE-a hears from another PE, say PE-b, a VPLS BGP announcement with
RT-foo and VE ID W, then PE-a knows that PE-b is a member of the same RT-foo and VE ID W, then PE-a knows that PE-b is a member of the same
VPLS (auto-discovery). PE-a then has to set up its part of a VPLS VPLS (autodiscovery). PE-a then has to set up its part of a VPLS
pseudowire between PE-a and PE-b, using the mechanisms in pseudowire between PE-a and PE-b, using the mechanisms in
Section 3.2. Similarly, PE-b will have discovered that PE-a is in Section 3.2. Similarly, PE-b will have discovered that PE-a is in
the same VPLS, and PE-b must set up its part of the VPLS pseudowire. the same VPLS, and PE-b must set up its part of the VPLS pseudowire.
Thus, signaling and pseudowire setup is also achieved with the same Thus, signaling and pseudowire setup is also achieved with the same
Update message. Update message.
If W is not in any remote VE set that PE-a announced for VE ID V in If W is not in any remote VE set that PE-a announced for VE ID V in
VPLS foo, PE-b will not be able to set up its part of the pseudowire VPLS foo, PE-b will not be able to set up its part of the pseudowire
to PE-a. To address this, PE-a can choose to withdraw the old to PE-a. To address this, PE-a can choose to withdraw the old
announcement(s) it made for VPLS foo, and announce a new Update with announcement(s) it made for VPLS foo, and announce a new Update with
skipping to change at page 14, line 25 skipping to change at page 16, line 22
and corresponding label block, and announce them in a new Update, and corresponding label block, and announce them in a new Update,
without withdrawing previous announcements. without withdrawing previous announcements.
If PE-a's configuration is changed to remove VE ID V from VPLS foo, If PE-a's configuration is changed to remove VE ID V from VPLS foo,
then PE-a MUST withdraw all its announcements for VPLS foo that then PE-a MUST withdraw all its announcements for VPLS foo that
contain VE ID V. If all of PE-a's links to its CEs in VPLS foo go contain VE ID V. If all of PE-a's links to its CEs in VPLS foo go
down, then PE-a SHOULD either withdraw all its NLRIs for VPLS foo, or down, then PE-a SHOULD either withdraw all its NLRIs for VPLS foo, or
let other PEs in the VPLS foo know in some way that PE-a is no longer let other PEs in the VPLS foo know in some way that PE-a is no longer
connected to its CEs. connected to its CEs.
3.4 Multi-AS VPLS 3.4. Multi-AS VPLS
As in [11] and [9], the above autodiscovery and signaling functions As in [13] and [10], the above autodiscovery and signaling functions
are typically announced via I-BGP. This assumes that all the sites are typically announced via I-BGP. This assumes that all the sites
in a VPLS are connected to PEs in a single Autonomous System (AS). in a VPLS are connected to PEs in a single Autonomous System (AS).
However, sites in a VPLS may connect to PEs in different ASes. This However, sites in a VPLS may connect to PEs in different ASes. This
leads to two issues: 1) there would not be an I-BGP connection leads to two issues: 1) there would not be an I-BGP connection
between those PEs, so some means of signaling across ASes may be between those PEs, so some means of signaling across ASes is needed;
needed; and 2) there may not be PE-to-PE tunnels between the ASes. and 2) there may not be PE-to-PE tunnels between the ASes.
A similar problem is solved in [9], Section 10. Three methods are A similar problem is solved in [10], Section 10. Three methods are
suggested to address issue (1); all these methods have analogs in suggested to address issue (1); all these methods have analogs in
multi-AS VPLS. multi-AS VPLS.
Here is a diagram for reference: Here is a diagram for reference:
__________ ____________ ____________ __________ __________ ____________ ____________ __________
/ \ / \ / \ / \ / \ / \ / \ / \
\___/ AS 1 \ / AS 2 \___/ \___/ AS 1 \ / AS 2 \___/
\ / \ /
+-----+ +-------+ | +-------+ +-----+ +-----+ +-------+ | +-------+ +-----+
| PE1 | ---...--- | ASBR1 | ======= | ASBR2 | ---...--- | PE2 | | PE1 | ---...--- | ASBR1 | ======= | ASBR2 | ---...--- | PE2 |
+-----+ +-------+ | +-------+ +-----+ +-----+ +-------+ | +-------+ +-----+
___ / \ ___ ___ / \ ___
/ \ / \ / \ / \ / \ / \
\__________/ \____________/ \____________/ \__________/ \__________/ \____________/ \____________/ \__________/
Figure 6: Inter-AS VPLS Figure 6: Inter-AS VPLS
As in the above reference, three methods for signaling inter-provider
VPLS are given; these are presented in order of increasing
scalability. Method (a) is the easiest to understand conceptually,
and the easiest to deploy; however, it requires an Ethernet
interconnect between the ASes, and both VPLS control and data plane
state on the AS border routers (ASBRs). Method (b) requires VPLS
control plane state on the ASBRs and MPLS on the AS-AS interconnect
(which need not be Ethernet). Method (c) requires MPLS on the AS-AS
interconnect, but no VPLS state of any kind on the ASBRs.
3.4.1 a) VPLS-to-VPLS connections at the AS border routers. 3.4.1. a) VPLS-to-VPLS connections at the ASBRs.
In this method, an AS Border Router (ASBR1) acts as a PE for all In this method, an AS Border Router (ASBR1) acts as a PE for all
VPLSs that span AS1 and an AS to which ASBR1 is connected, such as VPLSs that span AS1 and an AS to which ASBR1 is connected, such as
AS2 here. The ASBR on the neighboring AS (ASBR2) is viewed by ASBR1 AS2 here. The ASBR on the neighboring AS (ASBR2) is viewed by ASBR1
as a CE for the VPLSs that span AS1 and AS2; similarly, ASBR2 acts as as a CE for the VPLSs that span AS1 and AS2; similarly, ASBR2 acts as
a PE for this VPLS from AS2's point of view, and views ASBR1 as a CE. a PE for this VPLS from AS2's point of view, and views ASBR1 as a CE.
This method does not require MPLS on the ASBR1-ASBR2 link, but does This method does not require MPLS on the ASBR1-ASBR2 link, but does
require that this link carry Ethernet traffic, and that there be a require that this link carry Ethernet traffic, and that there be a
separate VLAN sub-interface for each VPLS traversing this link. It separate VLAN sub-interface for each VPLS traversing this link. It
further requires that ASBR1 does the PE operations (discovery, further requires that ASBR1 does the PE operations (discovery,
signaling, MAC address learning, flooding, encapsulation, etc.) for signaling, MAC address learning, flooding, encapsulation, etc.) for
all VPLSs that traverse ASBR1. This imposes a significant burden on all VPLSs that traverse ASBR1. This imposes a significant burden on
ASBR1, both on the control plane and the data plane, which limits the ASBR1, both on the control plane and the data plane, which limits the
number of multi-AS VPLSs. number of multi-AS VPLSs.
Note that in general, there will be multiple connections between a Note that in general, there will be multiple connections between a
pair of ASes, for redundancy. In this case, the Spanning Tree pair of ASes, for redundancy. In this case, the Spanning Tree
Protocol (STP), or some other means of loop detection and prevention, Protocol (STP) ([14]), or some other means of loop detection and
must be run on each VPLS that spans these ASes, so that a loop-free prevention, must be run on each VPLS that spans these ASes, so that a
topology can be constructed in each VPLS. This imposes a further loop-free topology can be constructed in each VPLS. This imposes a
burden on the ASBRs and PEs participating in those VPLSs, as these further burden on the ASBRs and PEs participating in those VPLSs, as
devices would need to run a loop detection algorithm for each such these devices would need to run a loop detection algorithm for each
VPLS. How this may be achieved is outside the scope of this such VPLS. How this may be achieved is outside the scope of this
document. document.
3.4.2 b) EBGP redistribution of VPLS information between ASBRs. 3.4.2. b) EBGP redistribution of VPLS information between ASBRs.
This method requires I-BGP peerings between the PEs in AS1 and ASBR1 This method requires I-BGP peerings between the PEs in AS1 and ASBR1
in AS1 (perhaps via route reflectors), an E-BGP peering between ASBR1 in AS1 (perhaps via route reflectors), an E-BGP peering between ASBR1
and ASBR2 in AS2, and I-BGP peerings between ASBR2 and the PEs in and ASBR2 in AS2, and I-BGP peerings between ASBR2 and the PEs in
AS2. In the above example, PE1 sends a VPLS NLRI to ASBR1 with a AS2. In the above example, PE1 sends a VPLS NLRI to ASBR1 with a
label block and itself as the BGP nexthop; ASBR1 sends the NLRI to label block and itself as the BGP nexthop; ASBR1 sends the NLRI to
ASBR2 with new labels and itself as the BGP nexthop; and ASBR2 sends ASBR2 with new labels and itself as the BGP nexthop; and ASBR2 sends
the NLRI to PE2 with new labels and itself as the nexthop. the NLRI to PE2 with new labels and itself as the nexthop.
The VPLS NLRI that ASBR1 sends to ASBR2 (and the NLRI that ASBR2 The VPLS NLRI that ASBR1 sends to ASBR2 (and the NLRI that ASBR2
skipping to change at page 16, line 44 skipping to change at page 18, line 38
In this method, one needs MPLS on the ASBR1-ASBR2 interface, but In this method, one needs MPLS on the ASBR1-ASBR2 interface, but
there is no requirement that the link layer be Ethernet. there is no requirement that the link layer be Ethernet.
Furthermore, the ASBRs take part in distributing VPLS information. Furthermore, the ASBRs take part in distributing VPLS information.
However, the data plane requirements of the ASBRs is much simpler However, the data plane requirements of the ASBRs is much simpler
than in method (a), being limited to label operations. Finally, the than in method (a), being limited to label operations. Finally, the
construction of loop-free VPLS topologies is done by routing construction of loop-free VPLS topologies is done by routing
decisions, viz. BGP path and nexthop selection, so there is no need decisions, viz. BGP path and nexthop selection, so there is no need
to run the Spanning Tree Protocol on a per-VPLS basis. Thus, this to run the Spanning Tree Protocol on a per-VPLS basis. Thus, this
method is considerably more scalable than method (a). method is considerably more scalable than method (a).
3.4.3 c) Multi-hop EBGP redistribution of VPLS information between 3.4.3. c) Multi-hop EBGP redistribution of VPLS information between
ASes. ASes.
In this method, there is a multi-hop E-BGP peering between the PEs In this method, there is a multi-hop E-BGP peering between the PEs
(or preferably, a Route Reflector) in AS1 and the PEs (or Route (or preferably, a Route Reflector) in AS1 and the PEs (or Route
Reflector) in AS2. PE1 sends a VPLS NLRI with labels and nexthop Reflector) in AS2. PE1 sends a VPLS NLRI with labels and nexthop
self to PE2; if this is via route reflectors, the BGP nexthop is not self to PE2; if this is via route reflectors, the BGP nexthop is not
changed. This requires that there be a tunnel LSP from PE1 to PE2. changed. This requires that there be a tunnel LSP from PE1 to PE2.
This tunnel LSP can be created exactly as in [10], section 10 (c),
This tunnel LSP can be created exactly as in [9], section 10 (c), for for example using E-BGP to exchange labeled IPv4 routes for the PE
example using E-BGP to exchange labeled IPv4 routes for the PE
loopbacks. loopbacks.
When PE1 wants to send a VPLS packet to PE2, it pushes the VPLS label When PE1 wants to send a VPLS packet to PE2, it pushes the VPLS label
corresponding to its own VE ID onto the packet. It then pushes the corresponding to its own VE ID onto the packet. It then pushes the
tunnel label(s) to reach PE2. tunnel label(s) to reach PE2.
This method requires no VPLS information (in either the control or This method requires no VPLS information (in either the control or
the data plane) on the ASBRs. The ASBRs only need to set up PE-to-PE the data plane) on the ASBRs. The ASBRs only need to set up PE-to-PE
tunnel LSPs in the control plane, and do label operations in the data tunnel LSPs in the control plane, and do label operations in the data
plane. Again, as in the case of method (b), the construction of plane. Again, as in the case of method (b), the construction of
loop-free VPLS topologies is done by routing decisions, i.e., BGP loop-free VPLS topologies is done by routing decisions, i.e., BGP
path and nexthop selection, so there is no need to run the Spanning path and nexthop selection, so there is no need to run the Spanning
Tree Protocol on a per-VPLS basis. This option is likely to be the Tree Protocol on a per-VPLS basis. This option is likely to be the
most scalable of the three methods presented here. most scalable of the three methods presented here.
3.4.4 Allocation of VE IDs Across Multiple ASes 3.4.4. Allocation of VE IDs Across Multiple ASes
In order to ease the allocation of VE IDs for a VPLS that spans In order to ease the allocation of VE IDs for a VPLS that spans
multiple ASes, one can allocate ranges for each AS. For example, AS1 multiple ASes, one can allocate ranges for each AS. For example, AS1
uses VE IDs in the range 1 to 100, AS2 from 101 to 200, etc. If uses VE IDs in the range 1 to 100, AS2 from 101 to 200, etc. If
there are 10 sites attached to AS1 and 20 to AS2, the allocated VE there are 10 sites attached to AS1 and 20 to AS2, the allocated VE
IDs could be 1-10 and 101 to 120. This minimizes the number of VPLS IDs could be 1-10 and 101 to 120. This minimizes the number of VPLS
NLRIs that are exchanged while ensuring that VE IDs are kept unique. NLRIs that are exchanged while ensuring that VE IDs are kept unique.
In the above example, if AS1 needed more than 100 sites, then another In the above example, if AS1 needed more than 100 sites, then another
range can be allocated to AS1. The only caveat is that there be no range can be allocated to AS1. The only caveat is that there be no
overlap between VE ID ranges among ASes. The exception to this rule overlap between VE ID ranges among ASes. The exception to this rule
is multi-homing, which is dealt with below. is multi-homing, which is dealt with below.
3.5 Multi-homing and Path Selection 3.5. Multi-homing and Path Selection
It is often desired to multi-home a VPLS site, i.e., to connect it to It is often desired to multi-home a VPLS site, i.e., to connect it to
multiple PEs, perhaps even in different ASes. In such a case, the multiple PEs, perhaps even in different ASes. In such a case, the
PEs connected to the same site can either be configured with the same PEs connected to the same site can either be configured with the same
VE ID or with different VE IDs. In the latter case, it is mandatory VE ID or with different VE IDs. In the latter case, it is mandatory
to run STP on the CE device, and possibly on the PEs, to construct a to run STP on the CE device, and possibly on the PEs, to construct a
loop-free VPLS topology. How this can be accomplished is outside the loop-free VPLS topology. How this can be accomplished is outside the
scope of this document; however, the rest of this section will scope of this document; however, the rest of this section will
describe in some detail the former case. describe in some detail the former case.
skipping to change at page 19, line 5 skipping to change at page 20, line 9
applies path selection to the remaining equivalent VPLS NLRIs to pick applies path selection to the remaining equivalent VPLS NLRIs to pick
another; if none remain, the forwarding information associated with another; if none remain, the forwarding information associated with
that NLRI is removed. that NLRI is removed.
Two VPLS NLRIs are considered equivalent from a path selection point Two VPLS NLRIs are considered equivalent from a path selection point
of view if the Route Distinguisher, the VE ID and the VE Block Offset of view if the Route Distinguisher, the VE ID and the VE Block Offset
are the same. If two PEs are assigned the same VE ID in a given are the same. If two PEs are assigned the same VE ID in a given
VPLS, they MUST use the same Route Distinguisher, and they SHOULD VPLS, they MUST use the same Route Distinguisher, and they SHOULD
announce the same VE Block Size for a given VE Offset. announce the same VE Block Size for a given VE Offset.
3.6. Hierarchical BGP VPLS
This section discusses how one can scale the VPLS control plane when
using BGP. There are at least three aspects of scaling the control
plane:
1. alleviating the full mesh connectivity requirement among VPLS BGP
speakers;
2. limiting BGP VPLS message passing to just the interested speakers
rather than all BGP speakers; and
3. simplifying the addition and deletion of BGP speakers, whether
for VPLS or other applications.
Fortunately, the use of BGP for Internet routing as well as for IP
VPNs has yielded several good solutions for all these problems. The
basic technique is hierarchy, using BGP Route Reflectors (RRs) ([6]).
The idea is to designate a small set of Route Reflectors which are
themselves fully meshed, and then establish a BGP session between
each BGP speaker and one or more RRs. In this way, there is no need
of direct full mesh connectivity among all the BGP speakers. If the
particular scaling needs of a provider requires a large number of
RRs, then this technique can be applied recursively: the full mesh
connectivity among the RRs can be brokered by yet another level of
RRs. The use of RRs solves problems 1 and 3 above.
It is important to note that RRs, as used for VPLS and VPNs, are
purely a control plane technique. The use of RRs introduces no data
plane state and no data plane forwarding requirements on the RRs, and
does not in any way change the forwarding path of VPLS traffic. This
is in contrast to the technique of Hierarchical VPLS defined in [8].
Another consequence of this approach is that it is not required that
one set of RRs handles all BGP messages, or that a particular RR
handle all messages from a given PE. One can define several sets of
RRs, for example a set to handle VPLS, another to handle IP VPNs and
another for Internet routing. Another partitioning could be to have
some subset of VPLSs and IP VPNs handled by one set of RRs, and
another subset of VPLSs and IP VPNs handled by another set of RRs;
the use of Route Target Filtering (RTF), described in [11] can make
this simpler and more effective.
Finally, problem 2 (that of limiting BGP VPLS message passing to just
the interested BGP speakers) is addressed by the use of RTF. This
technique is orthogonal to the use of RRs, but works well in
conjunction with RRs. RTF is also very effective in inter-AS VPLS;
more details on how RTF works and its benefits are provided in [11].
It is worth mentioning an aspect of the control plane that is often a
source of confusion. No MAC addresses are exchanged via BGP. All
MAC address learning and aging is done in the data plane individually
by each PE. The only task of BGP VPLS message exchange is
autodiscovery and label exchange.
Thus, BGP processing for VPLS occurs when
1. a PE joins or leaves a VPLS; or
2. a failure occurs in the network, bringing down a PE-PE tunnel or
a PE-CE link.
These events are relatively rare, and typically, each such event
causes one BGP update to be generated. Coupled with BGP's messaging
efficiency when used for signaling VPLS, these observations lead to
the conclusion that BGP as a control plane for VPLS will scale quite
well both in terms of processing and memory requirements.
4. Data Plane 4. Data Plane
This section discusses two aspects of the data plane for PEs and This section discusses two aspects of the data plane for PEs and
u-PEs implementing VPLS: encapsulation and forwarding. u-PEs implementing VPLS: encapsulation and forwarding.
4.1 Encapsulation 4.1. Encapsulation
Ethernet frames received from CE devices are encapsulated for Ethernet frames received from CE devices are encapsulated for
transmission over the packet switched network connecting the PEs. transmission over the packet switched network connecting the PEs.
The encapsulation is as in [10], with one change: a PE that sets the The encapsulation is as in [5], with one change: a PE that sets the P
P bit in the Control Flags strips the outermost VLAN from an Ethernet bit in the Control Flags strips the outermost VLAN from an Ethernet
frame received from a CE before encapsulating it, and pushes a VLAN frame received from a CE before encapsulating it, and pushes a VLAN
onto a decapsulated frame before sending it to a CE. onto a decapsulated frame before sending it to a CE.
4.2 Forwarding 4.2. Forwarding
VPLS packets are classified as belonging to a given service instance VPLS packets are classified as belonging to a given service instance
and associated forwarding table based on the interface over which the and associated forwarding table based on the interface over which the
packet is received. Packets are forwarded in the context of the packet is received. Packets are forwarded in the context of the
service instance based on the destination MAC address. The former service instance based on the destination MAC address. The former
mapping is determined by configuration. The latter is the focus of mapping is determined by configuration. The latter is the focus of
this section. this section.
4.2.1 MAC address learning 4.2.1. MAC address learning
As was mentioned earlier, the key distinguishing feature of VPLS is As was mentioned earlier, the key distinguishing feature of VPLS is
that it is a multipoint service. This means that the entire Service that it is a multipoint service. This means that the entire Service
Provider network should appear as a single logical learning bridge Provider network should appear as a single logical learning bridge
for each VPLS that the SP network supports. The logical ports for for each VPLS that the SP network supports. The logical ports for
the SP "bridge" are the customer ports on all of the VE on a given the SP "bridge" are the customer ports as well as the pseudowires on
service. Just as a learning bridge learns MAC addresses on its a VE. Just as a learning bridge learns MAC addresses on its ports,
ports, the SP bridge must learn MAC addresses at its VEs. the SP bridge must learn MAC addresses at its VEs.
Learning consists of associating source MAC addresses of packets with Learning consists of associating source MAC addresses of packets with
the (logical) ports on which they arrive; this association is the the (logical) ports on which they arrive; this association is the
Forwarding Information Base (FIB). The FIB is used for forwarding Forwarding Information Base (FIB). The FIB is used for forwarding
packets. For example, suppose the bridge receives a packet with packets. For example, suppose the bridge receives a packet with
source MAC address S on (logical) port P. If subsequently, the bridge source MAC address S on (logical) port P. If subsequently, the bridge
receives a packet with destination MAC address S, it knows that it receives a packet with destination MAC address S, it knows that it
should send the packet out on port P. should send the packet out on port P.
4.2.2 Flooding If a VE learns a source MAC address S on logical port P, then later
sees S on a different port P', then the VE MUST update its FIB to
reflect the new port P'. A VE MAY implement a mechanism to damp
flapping of source ports for a given MAC address.
4.2.2. Aging
VPLS PEs SHOULD have an aging mechanism to remove a MAC address
associated with a logical port, much the same as learning bridges do.
This is required so that a MAC address can be relearned if it "moves"
from a logical port to another logical port, either because the
station to which that MAC address belongs really has moved, or
because of a topology change in the LAN that causes this MAC address
to arrive on a new port. In addition, aging reduces the size of a
VPLS MAC table to just the active MAC addresses, rather than all MAC
addresses in that VPLS.
The "age" of a source MAC address S on a logical port P is the time
since it was last seen as a source MAC on port P. If the age exceeds
the aging time T, S MUST be flushed from the FIB. This of course
means that every time S is seen as a source MAC address on port P,
S's age is reset.
An implementation SHOULD provide a configurable knob to set the aging
time T on a per-VPLS basis. In addition, an implementation MAY
accelerate aging of all MAC addresses in a VPLS if it detects certain
situations, such as a Spanning Tree topology change in that VPLS.
4.2.3. Flooding
When a bridge receives a packet to a destination that is not in its When a bridge receives a packet to a destination that is not in its
FIB, it floods the packet on all the other ports. Similarly, a VE FIB, it floods the packet on all the other ports. Similarly, a VE
will flood packets to an unknown destination to all other VEs in the will flood packets to an unknown destination to all other VEs in the
VPLS. VPLS.
In Figure 1 above, if CE2 sent an Ethernet frame to PE2, and the In Figure 1 above, if CE2 sent an Ethernet frame to PE2, and the
destination MAC address on the frame was not in PE2's FIB (for that destination MAC address on the frame was not in PE2's FIB (for that
VPLS), then PE2 would be responsible for flooding that frame to every VPLS), then PE2 would be responsible for flooding that frame to every
other PE in the same VPLS. On receiving that frame, PE1 would be other PE in the same VPLS. On receiving that frame, PE1 would be
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knew which CE "owned" that MAC address). knew which CE "owned" that MAC address).
On the other hand, if PE3 received the frame, it could delegate On the other hand, if PE3 received the frame, it could delegate
further flooding of the frame to its u-PE. If PE3 was connected to 2 further flooding of the frame to its u-PE. If PE3 was connected to 2
u-PEs, it would announce that it has two u-PEs. PE3 could either u-PEs, it would announce that it has two u-PEs. PE3 could either
announce that it is incapable of flooding, in which case it would announce that it is incapable of flooding, in which case it would
receive two frames, one for each u-PE, or it could announce that it receive two frames, one for each u-PE, or it could announce that it
is capable of flooding, in which case it would receive one copy of is capable of flooding, in which case it would receive one copy of
the frame, which it would then send to both u-PEs. the frame, which it would then send to both u-PEs.
4.2.3 "Split Horizon" Forwarding 4.2.4. Broadcast and Multicast
When a PE capable of flooding receives a broadcast Ethernet frame, or There is a well-known broadcast MAC address. An Ethernet frame whose
one with an unknown destination MAC address, it must flood the frame. destination MAC address is the broadcast MAC address must be sent to
If the frame arrived from an attached CE, the PE must send a copy of all stations in that VPLS. This can be accomplished by the same
the frame to every other attached CE, as well as to all PEs means that is used for flooding.
participating in the VPLS. If the frame arrived from another PE,
however, the PE must only send a copy of the packet to attached CEs.
The PE MUST NOT send the frame to other PEs. This notion has been
termed "split horizon" forwarding, and is a consequence of the PEs
being logically full-meshed -- if a broadcast frame is received from
PEx, then PEx would have sent a copy to all other PEs.
Split horizon forwarding rules also apply to multicast frames (i.e., There is also an easily recognized set of "multicast" MAC addresses.
those with a multicast destination MAC address). In this case, when Ethernet frames with a destination multicast MAC address MAY be
a PE receives a multicast frame from another PE, the frame is broadcast to all stations; a VE MAY also use certain techniques to
replicated and sent to the relevant subset of attached CEs; however, restrict transmission of multicast frames to a smaller set of
it MUST NOT be sent to other PEs. receivers, those that have indicated interest in the corresponding
multicast group. Discussion of this is outside the scope of this
document.
4.2.5. "Split Horizon" Forwarding
When a PE capable of flooding (say PEx) receives a broadcast Ethernet
frame, or one with an unknown destination MAC address, it must flood
the frame. If the frame arrived from an attached CE, PEx must send a
copy of the frame to every other attached CE, as well as to all other
PEs participating in the VPLS. If, on the other hand, the frame
arrived from another PE (say PEy), PEx must send a copy of the packet
only to attached CEs. PEx MUST NOT send the frame to other PEs,
since PEy would have already done so. This notion has been termed
"split horizon" forwarding, and is a consequence of the PEs being
logically fully meshed for VPLS.
Split horizon forwarding rules apply to broadcast and multicast
packets, as well as packets to an unknown MAC address.
4.2.6. Qualified and Unqualified Learning
The key for normal Ethernet MAC learning is usually just the
(6-octet) MAC address. This is called "unqualified learning".
However, it is also possible that the key for learning includes the
VLAN tag when present; this is called "qualified learning".
In the case of VPLS, learning is done in the context of a VPLS
instance, which typically corresponds to a customer. If the customer
uses VLAN tags, one can make the same distinctions of qualified and
unqualified learning. If the key for learning within a VPLS is just
the MAC address, then this VPLS is operating under unqualified
learning. If the key for learning is (customer VLAN tag + MAC
address), then this VPLS is operating under qualified learning.
Choosing between qualified and unqualified learning involves several
factors, the most important of which is whether one wants a single
global broadcast domain (unqualified), or a broadcast domain per VLAN
(qualified). The latter makes flooding and broadcasting more
efficient, but requires larger MAC tables. These considerations
apply equally to normal Ethernet forwarding and to VPLS.
4.2.7. Class of Service
In order to offer different Classes of Service within a VPLS, an
implementation MAY choose to map 802.1p bits in a customer Ethernet
frame with a VLAN tag to an appropriate setting of EXP bits in the
pseudowire and/or tunnel label, allowing for differential treatment
of VPLS frames in the packet-switched network.
To be useful, an implementation SHOULD allow this mapping function to
be different for each VPLS, as each VPLS customer may have their own
view of the required behavior for a given setting of 802.1p bits.
5. Deployment Options 5. Deployment Options
In deploying a network that supports VPLS, the SP must decide what In deploying a network that supports VPLS, the SP must decide what
functions the VPLS-aware device closest to the customer (the VE) functions the VPLS-aware device closest to the customer (the VE)
supports. The default case described in this document is that the VE supports. The default case described in this document is that the VE
is a PE. However, there are a number of reasons that the VE might be is a PE. However, there are a number of reasons that the VE might be
a device that does all the Layer 2 functions (such as MAC address a device that does all the Layer 2 functions (such as MAC address
learning and flooding), and a limited set of Layer 3 functions (such learning and flooding), and a limited set of Layer 3 functions (such
as communicating to its PE), but, for example, doesn't do full- as communicating to its PE), but, for example, doesn't do full-
skipping to change at page 23, line 8 skipping to change at page 28, line 8
well-behaved (this is outside the scope of this document), and that well-behaved (this is outside the scope of this document), and that
VPLS labels are accepted only from valid interfaces. For a PE, valid VPLS labels are accepted only from valid interfaces. For a PE, valid
interfaces comprise links from P routers. For an ASBR, a valid interfaces comprise links from P routers. For an ASBR, a valid
interface is a link from an ASBR in an AS that is part of a given interface is a link from an ASBR in an AS that is part of a given
VPLS. It is especially important in the case of multi-AS VPLSs that VPLS. It is especially important in the case of multi-AS VPLSs that
one accept VPLS packets only from valid interfaces. one accept VPLS packets only from valid interfaces.
7. IANA Considerations 7. IANA Considerations
IANA is asked to allocate an AFI for L2VPN information (suggested IANA is asked to allocate an AFI for L2VPN information (suggested
value: 25). This should be the same as the AFI requested by [8]. value: 25). [NOTE to IANA: This should be the same as the AFI
requested by [9].]
8. References 8. References
8.1 Normative References 8.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[2] Heffernan, A., "Protection of BGP Sessions via the TCP MD5 [2] Heffernan, A., "Protection of BGP Sessions via the TCP MD5
Signature Option", RFC 2385, August 1998. Signature Option", RFC 2385, August 1998.
[3] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, "Multiprotocol [3] Bates, T., "Multiprotocol Extensions for BGP-4",
Extensions for BGP-4", draft-ietf-idr-rfc2858bis-06 (work in draft-ietf-idr-rfc2858bis-07 (work in progress), August 2005.
progress), May 2004.
[4] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended [4] Rekhter, Y., "BGP Extended Communities Attribute",
Communities Attribute", draft-ietf-idr-bgp-ext-communities-08 draft-ietf-idr-bgp-ext-communities-09 (work in progress),
(work in progress), February 2005. July 2005.
[5] Martini, L., "Encapsulation Methods for Transport of Ethernet [5] Martini, L., "Encapsulation Methods for Transport of Ethernet
Frames Over MPLS Networks", draft-ietf-pwe3-ethernet-encap-09 Over MPLS Networks", draft-ietf-pwe3-ethernet-encap-11 (work in
(work in progress), February 2005. progress), December 2005.
8.2 Informative References 8.2. Informative References
[6] Andersson, L. and E. Rosen, "Framework for Layer 2 Virtual [6] Bates, T., Chandra, R., and E. Chen, "BGP Route Reflection - An
Alternative to Full Mesh IBGP", RFC 2796, April 2000.
[7] Andersson, L. and E. Rosen, "Framework for Layer 2 Virtual
Private Networks (L2VPNs)", draft-ietf-l2vpn-l2-framework-05 Private Networks (L2VPNs)", draft-ietf-l2vpn-l2-framework-05
(work in progress), June 2004. (work in progress), June 2004.
[7] Lasserre, M. and V. Kompella, "Virtual Private LAN Services [8] Lasserre, M. and V. Kompella, "Virtual Private LAN Services
over MPLS", draft-ietf-l2vpn-vpls-ldp-06 (work in progress), over MPLS", draft-ietf-l2vpn-vpls-ldp-08 (work in progress),
February 2005. November 2005.
[8] Ould-Brahim, H., Rosen, E., and Y. Rekhter, "Using BGP as an [9] Ould-Brahim, H., "Using BGP as an Auto-Discovery Mechanism for
Auto-Discovery Mechanism for Layer-3 and Layer-2 VPNs", Layer-3 and Layer-2 VPNs", draft-ietf-l3vpn-bgpvpn-auto-06
draft-ietf-l3vpn-bgpvpn-auto-05 (work in progress), (work in progress), June 2005.
February 2005.
[9] Rosen, E., "BGP/MPLS IP VPNs", draft-ietf-l3vpn-rfc2547bis-03 [10] Rosen, E., "BGP/MPLS IP VPNs", draft-ietf-l3vpn-rfc2547bis-03
(work in progress), October 2004. (work in progress), October 2004.
[10] Martini, L., "Pseudowire Setup and Maintenance using LDP", [11] Marques, P., "Constrained VPN Route Distribution",
draft-ietf-pwe3-control-protocol-16 (work in progress), draft-ietf-l3vpn-rt-constrain-02 (work in progress), June 2005.
March 2005.
[11] Kompella, K., "Layer 2 VPNs Over Tunnels",
draft-kompella-l2vpn-l2vpn-00 (work in progress), January 2004.
Authors' Addresses
Kireeti Kompella (editor)
Juniper Networks
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: kireeti@juniper.net [12] Martini, L., "Pseudowire Setup and Maintenance using the Label
Distribution Protocol", draft-ietf-pwe3-control-protocol-17
(work in progress), June 2005.
Yakov Rekhter (editor) [13] Kompella, K., "Layer 2 VPNs Over Tunnels",
Juniper Networks draft-kompella-l2vpn-l2vpn-00 (work in progress), January 2004.
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: kireeti@juniper.net [14] Institute of Electrical and Electronics Engineers, "Information
technology - Telecommunications and information exchange
between systems - Local and metropolitan area networks - Common
specifications - Part 3: Media Access Control (MAC) Bridges:
Revision. This is a revision of ISO/IEC 10038: 1993, 802.1j-
1992 and 802.6k-1992. It incorporates P802.11c, P802.1p and
P802.12e. ISO/IEC 15802-3: 1998.", IEEE Standard 802.1D,
July 1998.
Appendix A. Contributors Appendix A. Contributors
The following contributed to this document: The following contributed to this document:
Javier Achirica, Telefonica Javier Achirica, Telefonica
Loa Andersson, Acreo Loa Andersson, Acreo
Chaitanya Kodeboyina, Juniper Chaitanya Kodeboyina, Juniper
Giles Heron, Alcatel Giles Heron, Tellabs
Sunil Khandekar, Alcatel Sunil Khandekar, Alcatel
Vach Kompella, Alcatel Vach Kompella, Alcatel
Marc Lasserre, Riverstone Marc Lasserre, Riverstone
Pierre Lin Pierre Lin
Pascal Menezes Pascal Menezes
Ashwin Moranganti, Appian Ashwin Moranganti, Appian
Hamid Ould-Brahim, Nortel Hamid Ould-Brahim, Nortel
Seo Yeong-il, Korea Tel Seo Yeong-il, Korea Tel
Appendix B. Acknowledgements Appendix B. Acknowledgements
Thanks to Joe Regan and Alfred Nothaft for their contributions. Many Thanks to Joe Regan and Alfred Nothaft for their contributions. Many
thanks too to Eric Ji, Chaitanya Kodeboyina, and Mike Loomis for thanks too to Eric Ji, Chaitanya Kodeboyina, Mike Loomis and Elwyn
their detailed reviews. Davies for their detailed reviews.
Authors' Addresses
Kireeti Kompella (editor)
Juniper Networks
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: kireeti@juniper.net
Yakov Rekhter (editor)
Juniper Networks
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: yakov@juniper.net
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
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