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VPLS via IS-IS for Data Centers

This document proposes extending IS-IS to support VPLS signaling and auto-discovery in a lightweight manner. It describes adding a new TLV to IS-IS to advertise VPLS membership. PE routers would use this to automatically discover other PEs in a VPLS and assign the same MPLS label for signaling without needing separate BGP or LDP sessions. The control plane on P routers is unaffected, and only data forwarding behavior on PEs needs to change to use the source IP for MAC learning instead of the VPLS label. Next steps are to get more WG feedback and ask for adoption of this IS-IS VPLS proposal.

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115 views7 pages

VPLS via IS-IS for Data Centers

This document proposes extending IS-IS to support VPLS signaling and auto-discovery in a lightweight manner. It describes adding a new TLV to IS-IS to advertise VPLS membership. PE routers would use this to automatically discover other PEs in a VPLS and assign the same MPLS label for signaling without needing separate BGP or LDP sessions. The control plane on P routers is unaffected, and only data forwarding behavior on PEs needs to change to use the source IP for MAC learning instead of the VPLS label. Next steps are to get more WG feedback and ask for adoption of this IS-IS VPLS proposal.

Uploaded by

aslamzohaib
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© © All Rights Reserved
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VPLS using IS-IS

draft-xu-l2vpn-vpls-isis-00

Xiaohu Xu (xuxh@huawei.com) www.huawei.com

IETF 80, Prague



Motivation!
l  VPLS could be a good option for cloud data center network
 technology due to its following capabilities:
p  Shortest path forwarding.
p  Equal Cost Multi-Path (ECMP).
p  A large amount of VPN instances (>4096).
p  Forwarding table scalability, especially for P routers.
l  However, BGP VPLS [RFC4761] and LDP VPLS [RFC4762]
protocols seem a bit heavy-weight.
p  Separate protocol for VPLS should be deployed besides IGP.
l  Could the already deployed IGP (e.g., IS-IS) be extended a
bit so as to deliver a light-weight VPLS?

Page 2


Extended IS-IS TLV for VPLS

Page 3

Auto-Discovery and Signaling in IS-IS VPLS


l  Auto-Discovery
p  Each PE router could automatically discover which other PE routers
are part of a given VPLS instance identified by the globally unique
VPLS ID.
p  PE router's configuration consists only of the identities of the VPLS
instances established on this PE router, not the identities of any other
PE routers belonging to that VPLS instance.
l  Signaling
p  PE router assigns the same MPLS label for a given VPLS instance to
any other PE routers.
p  The VPLS label doesn’t need to be globally unique. 

Page 4


Implications on the Control Plane!


l  The extended IS-IS TLV for VPLS is partially transparent to P
routers.
p  P routers don't need to process the VPLS membership information
contained in that IS-IS TLV, but only need to synchronize the Link
State PDUs with their IS-IS neighbors.

Page 5


Implications on the Data Plane


l  Data encapsulation and data forwarding are not changed.
l  The only change is to the data-driven MAC learning:
p  The VPLS label in the received VPLS packet is only intended to
identify a given VPLS instance on the egress PE.
p  Hence, the source IP address in the IP-based tunnel header should
be resorted to identify the ingress PE of the received VPLS packet.

Page 6


Next Steps


l  Solicit more comments from the WG.
l  Ask for WG adoption.

Page 7

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