From: Thomas Bridge (thomasb@gmail.com)
Date: Mon Aug 02 2004 - 13:04:29 GMT-3
On Mon, 2 Aug 2004 12:19:42 +0100, steve.skinner@uk.pwc.com
<steve.skinner@uk.pwc.com> wrote:
> i have a quiery regarding
>
> IS -IS
>
> R1 (l1/l2) ------R2 (L1/L2)-----R3 L1
>
> R1 and R2/3 are in the same area
>
> this is about routes seen from R3
>
> if on R1 i do two things
>
> redistribute ip static type-L1 ( i think )
>
> this put`smy connected interfaces ( lo10) into L1 only ( i.,e loopback
> 150.150.1.1)
> and
> i advertisre a summary addres of 150.150.1.0 ( same class) into L2 only
>
> i now have two routes for 150.150.1.1..
> 1 coming from an L1 update ...and 1 from an L2 update
>
> if both these routes were both identical ( which bieng a summary that would
> not usually be the case )
>
> then R3 should recieve two route`s
> 1 from the L1 update and 1 from the L2 update .
>
> which 1 would go into the main ip routing table ???
>
> iam not doing route leaking or anything else
Funny - I was probably doing a scenario with ISIS at the exact time
you sent this email.
I had the following situation:
R7 - (serial link) - R8
Both in the same area. With the default settings for isis R7 was
inserting Level 1 routes into the routing table.
By enabling "isis circuit-type level-2-only" on R7's serial interface,
I ensured that the ISIS routes on R7 were Level 2 routes.
So I think the answer is that ISIS will insert Level 1 routes if it
has a choice between Level 1 and Level 2 routes.
Thomas
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