Subject: RE: [Isis-wg] isisSysInstance

From: Anand Ammundi <[email-masked]>
Date: Wed, 10 Oct 2001 17:15:11 -0700

Biju,
 my 2C on this...
 firstly most of the multi-instance routing protocol is
 fairly vendor specific. One of driving forces behind 
 multi-instancing is from the VPN angle. So for example, 
 BGP with 2547 would route between PE's, preserving the 
 respective VPN route identities, while the local CE - PE
 IGP (typically RIP or OSPF) would multi-instance themselves,
 typically per VPN routing space and run independently.
 (and then there is that virtual router !!)
 IP for it's part would have to maintain it's routes seperately
 per VPN, but here is where things are different from vendor 
 to vendor. One could have a many-to-many relationship between 
 IGP and IP. so you could have multi-instance IS-IS over 1 IP
 as also an instance over an instance of IP. (do note when I say
 ISIS o IP, I mean the routing table part)
 However, whatever be the implementation, the LSP database 
 would logically be separate for each instance and each instance
 runs on its own steam.
 I don't know much about Cisco multi-area support though.

 hope this helps. 
 regards
 anand

-----Original Message-----
From: Mammen, Biju [mailto:[email-masked]]
Sent: Wednesday, October 10, 2001 4:24 PM
To: [email-masked]'
Subject: [Isis-wg] isisSysInstance

Hello all,
This question seems to have popped up time and again but have gone 
unanswered on all occasions. Some guidance is really appreciated: 

a) What would be the implication of defining multiple instances of 
ISIS (as per draft-ietf-isis-wg-mib-05.txt)?

b) Would all these instances work on the same Unified routing table or
different ones?

c) Would each of this instance have its own LSDatabases?

d) Is this the same as CISCO's view of multi area support in a single
router?
( A single Level 2 and 28 Level 1s)

Thanks and regards
Biju

_______________________________________________
Isis-wg mailing list  -  [email-masked]
http://external.juniper.net/mailman/listinfo/isis-wg