Subject: [Isis-wg] up/down bit question..

From: Saravana Kumar <[email-masked]>
Date: Tue, 03 Sep 2002 11:34:17 -0600

Hi Everyone,

I have a little doubt on the section about the up/down bit in the 
ISIS IPV6 draft, which goes like this..

  "As is described in [2], "the up/down bit is set to 0 when a 
   prefix is first injected into IS-IS.  If a prefix is 
   redistributed from a higher level to a lower level (e.g., 
   level two to level one), the bit shall be set to 1 to indicate
   that the prefix has travelled down the hierarchy.  If a prefix
   is redistributed from an area to another area at the same level
   then the up/down bit shall be set to 1."

I can understand the first two cases, but i cant put my finger on the
third. In which cases do we re-distribute from one area to another 
area 'at the same level' ?

If we re-distribute the routes from one area 'A' into another area 'B',
my guess is that it will be done by the L1L2 router in area 'B',which
would actually do a selective L2->L1 prefix distribution ( i.e 
distributing all the prefixes that it learns from the L2 LSP's coming 
from area 'A') This is again a case of redistributing routes from a 
higher level to a lower level. When do we redistribute from an area to
another area at the same level ?

Thanks,
Sarav

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From: Chris Hopps <[email-masked]>
Date: Thu, 5 Sep 2002 11:34:31 -0700

Perhaps I didn't quote enough from [2] :)

If you look at the referenced document you'll find:

   "If a prefix is advertised from an area to another area at the same
   level, then the up/down bit shall be set to 1. This situation can
   arise when a router implements multiple virtual routers at the same
   level, but in different areas."

Chris.

-----Original Message-----
From: Saravana Kumar [mailto:[email-masked]]
Sent: Tuesday, September 03, 2002 10:34 AM
To: [email-masked]
Subject: [Isis-wg] up/down bit question..

Hi Everyone,

Thanks,
Sarav

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From: Saravana Kumar <[email-masked]>
Date: Thu, 05 Sep 2002 13:08:18 -0600

>   level, but in different areas."

Ah well.. that makes sense !! Thanks Chris..
Sarav

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From: "Abarbanel, Benjamin" <[email-masked]>
Date: Thu, 5 Sep 2002 15:48:31 -0400

Hi Chris:

Got a general but basic question for you. Can you leak IPv4 L1L2 addresses
into IPv6 L1L2 LSP database and vice versa? 

Do you keep one LSP database containing both IP address families; or two LSP
databases one for each IP address family?

Ben

> From: Chris Hopps [mailto:[email-masked]]
> Sent: Thursday, September 05, 2002 2:35 PM
> To: [email-masked]'
> Cc: [email-masked]
> Subject: RE: [Isis-wg] up/down bit question..
> 
>