[c-nsp] IS-IS question

[sthaug at nethelp.no]

> All routers (CRs and PE1) are IS-IS Level-2-only routers. All links
> are OC48 POS.
> If link between CR1 and CR2 fail then traffic between CR2 and CR1 will
> be transited over PE1.
> 
> My solution to bypass this is set much higher metrics at links between
> CRs and PEs than metrics inside core. Is my method is good ? Do you
> have any other recommendations regarding migration from EIGRP to IS-IS
> ? (routers are mostly GSR and 6500/7600 + 3750 L3 for Datacenter + new
> Junipers will be few M320).

The simplest solutions are often the best, and adjusting the IGP metrics
should work just fine for this case. Since you mention PE routers, you
possibly have an MPLS network - in which case there are several other
tools available (LSPs with explicit paths, link coloring, etc).

Steinar Haug, Nethelp consulting, sthaug at nethelp.no