[c-nsp] ISIS Distance question

[Oliver Boehmer (oboehmer)]

>Hi JC,
>
>> The real life problem is A and B are PE routers and C is the RR. So I
>>do not
>> have MPLS on the interfaces towards C from A & B. So when the A-B link
>> fails, it will break the label switched path between them. A and B have
>>CsC
>> links which should then be preferred..
>
>If you are using separate Control-Plane (RRs that are not part of the
>MPLS/data-plane) you may set the overload bit on your RRs via the "router
>isis" cmd: "set-overload-bit".
>This will assign maximum ISIS metric to all links advertised by the RR
>-this will assure that RR will never end up on the forwarding path
>between any two PEs.

indeed overload bit would be the best approach.. and to be exact: an IS
with OL-bit set will never be considered as transit while building the
SPF, no matter how high or low the link metrics are.. OSPF, short of an
OL-bit concept, will use max metrics to achieve the same..

	oli