[c-nsp] Rationale for ISIS default origination behavior

[John Neiberger]

We have static routes on the ASBRs that point to the loopback of the eBGP
peer, then we redistribute those statics into ISIS. If a peer loopback goes
away, the network converges pretty quickly to the other available
connections.

But thinking about that, it once again makes me wonder why we are
redistributing the default into ISIS. If the default already exists in iBGP
and the next-hop is in ISIS, that's going to converge pretty quickly. I'll
have to think about this some more. There's probably some obvious factor
that I'm overlooking.



On Tue, Jan 22, 2013 at 1:09 AM, Adam Vitkovsky <adam.vitkovsky at swan.sk>wrote:

> > However, we also configure the routers with eBGP peers to originate
> defaults into the IGP, presumably for faster convergence, although given
> the
> design I really don't know that convergence will be that much faster.
>
>
> So than you must also be using the "bgp nexthop route-map" or "nexthop
> route-policy" in order to control what routes are valid for iBGP next-hops
> right?
> Cause if the /32 route for some peer's loopback/iBGP next-hop disappears
> form ISIS I guess you don't want to follow default route to get to that
> peer
>
>
> adam
>
>