Subject: ERO List with numbered and unnumbered interfaces

From: Bora Akyol <[email-masked]>
Date: Mon, 02 Oct 2000 18:33:35 -0700

When filling in the ERO, there are three options:

1) Put in the router ID of the routers. This does not work for cases
when routers have multiple links and for unnumbered interfaces.

2) Put in the egress interface of the routers on the path and finish it
with the router ID of the final router. So that from router A to router
B, we represent the hop as the IP address/interface index of the
interface from A to B on router A.

3) Put in the ingress interface of the routers on the path starting with
the router ID of ingress and finishing with the router ID of the egress
LSRs. This is kind of opposite of (2).

I believe that (2) is the only option that works with unnumbered
interfaces.

Does anyone think otherwise?

Bora

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From: Markus Jork <[email-masked]>
Date: Tue, 03 Oct 2000 09:49:29 -0400

Bora,

> Does anyone think otherwise?

your option (1) will work when you only have a single link (which may
be unnumbered) between the routers. Using router IDs in the
ERO may also be useful in the presence of multiple links when you
don't care which of the multiple links between a pair of routers will
be used.

I'm kind of confused about your option (2). Have you read
draft-kompella-mpls-unnum or are you trying to reinvent it here?

Markus

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From: Bora Akyol <[email-masked]>
Date: Tue, 03 Oct 2000 10:33:52 -0700

> don't care which of the multiple links between a pair of routers will

Thanks for pointing out the obvious which I have already stated in my previous
email. Next time, you may want to actually read the message before jumping on
the trigger ;-)

> draft-kompella-mpls-unnum or are you trying to reinvent it here?

Yes, and this is exactly why I think only option (2) would work, since only
the local router has information about its ifindex to interface mapping.

Bora

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From: Markus Jork <[email-masked]>
Date: Wed, 04 Oct 2000 10:32:15 -0400

Bora,

> email. Next time, you may want to actually read the message before jumping on

Yes, one of us should have read your previous message more thoroughly :-)
I'm sure you knew all this but you did write just the opposite in
your message, namely that option (1) does *not* work with unnumbered

> when routers have multiple links and for unnumbered interfaces.

This is why I felt compelled to state the obvious...

Markus