[j-nsp] Joining OPSF & IS-IS areas via 2 ABRs

[Clarke Morledge]

On Sat, 9 Oct 2010, Smith W. Stacy wrote:

> I think you misunderstood. My example in no way requires virtual/logical 
> routers. I simply used them because I only had access to a single 
> physical router and wanted to create a more complex topology to verify 
> the solution to your redistribution question.
>
> The only configuration necessary is on abr1 and abr2.
>
> The other routers in my topology (ospf1, ospf2, isis1, and isis2) were 
> simply to verify the redistribution on abr1 and abr2 was working 
> correctly. ospf1 and ospf2 are OSPF-only speaking routers. isis1 and 
> isis2 are ISIS-only speaking routers.
>
> --Stacy

Stacy,

Oh, I understood you completely.

In fact, you didn't know it, but the idea of virtual/logical routers is a 
more elegant solution in my case.  In my case, abr1 and isis1 are but one 
physical router -- same for abr2 and isis2. My only problem is the issue 
of stealing bandwidth from the MX PFEs to support 10Gig logical tunnels.

On the isis-only speaking routers (isis1 and isis2), getting transit 
traffic to go where I want it to go via abr1 or abr2 is easy.  The 
problem, for example, is with traffic coming in from some *other* 
isis-only router, isis3, via abr2.  In this case, physically isis3 must 
pass traffic through abr2 to get to abr1. I want that traffic to transit 
through abr1-ospf1 to the OSPF world, but since ospf internal routes have 
a better preference over isis routes, it will take the abr2-ospf2 path 
when it hits abr2, even though the metric from isis is engineered to be 
better going through the isis domain via abr1.

In other words, dropping in a separate abr1 and abr2 router between the 
ospf and isis worlds is a lot cleaner  -- but it costs me something in 
terms of bandwidth resources to support the logical tunnels.

Does that clarify my challenge a bit?

P.S. I just wish the vendor of my OSPF-only routers would support ISIS in 
a virtual routing environment.  Life would be simpler :-)

Clarke