[c-nsp] IS-IS question

[Robert Hass]

Hi
We just migrating our network from EIGRP to IS-IS. We have to migrate
due to we will install few Junipers next to current Cisco routers. I
already read few documents regarding IS-IS, but I'm not sure about my
solution to preventing transit via access router instead of
core/backbone.

For example we have part of network:

CR3---------CR4
|             |
|             |
|             |
CR1----------CR2
\           /
 \         /
  \       /
   \     /
    \   /
     PE1
       |
       |
   customers

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).

Thanks,
Robert