From: Aidan Marks (aidan@cisco.com)
Date: Mon Dec 29 2003 - 02:51:15 GMT-3
At 10:30 AM 28/12/2003, Jonathan Hays wrote:
>you wrote:
>Until I added the redistribute connected under the ospf and is-is I
>could
>see the routes on R4 but they were not pingable.
[snip]
>I'm not sure anyone has posted an in-depth coherent discussion of the
>internal working of IS-IS
>on this list. And I think that is the ultimate reason for this behavior.
I have responded to this before but I couldn't find it so I'll quickly
cover it again. ISIS doesn't use the 'network' command, so a special bit
does not get set on each connected route. When protocol X is evaluating a
route for redistribution from protocol Y, it checks to see if it is either
owned by Y or if this special bit if set. Since we don't set the bit for
connected routes with ISIS, no redistribution happens.
This is behaviour only to ISIS. A known low priority issue for a long
time, might be fixed one day, until then use the well understood workaround.
Aidan
>Regardless of the underlying theory, be prepared to redistribute
>connected into ISIS, regardless of what the other protocol is. I doubt
>you would be penalized (but I'm not a Cisco exam grader) it's also a
>good idea to use a route map whenever doing redistribute connected. It's
>best to lock down everything you can in your configuration. The more
>control, the better. And when you create a route-map for a connected
>interface you can skip the extra step of creating an access-list:
>
>redistribute connected route-map CONN2ISIS
>!
>route-map CONN2ISIS
> match interface Serial0/0.123 loopback 0
>
>The book "IS-IS Network Design Solutions" by Abe Martey (ISBN
>1-57870-220-8) has a 26 page section (pages 192-217) entitled "Comparing
>Integrated IS-IS and OSPF." There is also a brief section on
>redistribution (pages 273-278) but I don't believe the specific issue of
>"redistribute connected" is examined in the book. However, it's a great
>resource for CCIE Lab preparation.
>
>That said, the ISIS Technical Support page is a good place to start
>looking for answers:
>
>http://www.cisco.com/pcgi-bin/Support/browse/psp_view.pl?p=Internetworki
>ng:ISIS&viewall=true
>
>Have fun!
>
>Jonathan
>
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