Technical Summary
This document describes the Virtual Private LAN Service (VPLS), also known as
Transparent LAN Service and Virtual Private Switched Network service. The
service offers a Layer 2 Virtual Private Network (VPN); however, in the case
ofVPLS, the customers in the VPN are connected by a multipoint network, in
contrast to traditional Layer 2 VPNs, which are point-to-point in nature.
Thisdocument describes the functions required to offer VPLS, a mechanism for
signaling a VPLS using BGP, and rules for forwarding VPLS frames across a
packet switched network.
Working Group Summary
The VPLS solutions have been one of great controversies within the VPN
workinggroups ever since the PPVPN days. There have been two sets of
solutionsand
much debate on the relative merits of these solutions. An agreement was
reached that it is not really the choice of signaling protocol that is the
major difference between the LDP and BGP based solutions, but the kind of
environment they are targeted at. VPLS-LDP is aimed at a market of networks
built on relatively small and functionally simple switches, while VPLS-BGP is
primarily suited for use by high-end routers. There is a comparatively good
understanding for this agreement in the working group. Within the working
group there is no one that wants to go over that debate again. VPLS-BGP has
been through a number of reviews, including reviews in the L2VPN working group
and the IDR WG. We know that Alex has requested that it shall be reviewed in
routing directorate.
Protocol Quality
The protocol is implemented and deployed. There is one vendor who is known
tohave implemented, and widely deployed, the VPLS-BGP spec. There is believed
to
be two other implementations, but that hasn't been confirmed. The number of
deployments is larger, but I don't have figures. We have not had any reviewer
stand up and saying there is any need for major re-work. This is most likely
attributable to the fact that this specification is rather limited in scope,
specifically: signaling and discovery of VPLS instances.
The specification has been reviewed by Alex Zinin, the IDR WG, and
Mark Townsley.
IESG Note
The L2VPN Working Group produced two separate documents,
[RFC-draft-ietf-l2vpn-vpls-ldp] and [RFC-draft-ietf-l2vpn-vpls-bgp], that
ultimately perform similar functions in different manners. Be aware that each
method is commonly referred to as "VPLS" even though they are distinct and
incompatible with one another.