IS-IS and BGP as CE-PE

Reza Sharifi · ‎09-30-2008

Hi,

Does any one know or has a document that explains why IS-IS is not supported as a protocol to use on CE routers?

Also, more specifically, IS-IS is not supported, because you can not run it per VRF?

I am just trying to understand why we can't use IS-IS the same way we use OSPF.

Thanks,

Reza

Harold Ritter · ‎09-30-2008

Reza,

ISIS is actually VRF aware.

http://www.cisco.com/en/US/docs/ios/iproute/configuration/guide/is_instance_vrf.html

What is missing is the standardization to use it as a CE-PE protocol. If you look at OSPF for instance, it required an RFC explaining how OSPF attributes could be propagated from one PE to the other using BGP extended communities (see RFC4577). This has not happen yet for ISIS and i haven't heard of anything coming soon in the IETF.

Regards

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
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Reza Sharifi · ‎09-30-2008

Harold,

Thanks for the link and explanation.

I will take a look at RFC4577.

Reza