Subject: Failover Tunnels

From: "Jung, Michael" <[email-masked]>
Date: Thu, 11 Apr 96 15:09:00 PDT

I am trying to understand how to configure fail-over tunnels from two
c7000 Routers Version 11.0(4), RELEASE SOFTWARE (fc1)
to a box running mrouted 3.8.2.

After configuring the two tunnels I have observed the following by   
watching
the debug output of mrouted and looking at "show IP mroute".

1)  vif(1) mrouted acts normally, send prunes, c7000 indicates groups   
pruned.
2)  vif(2) mrouted does not send prunes, c7000 indicates no prunes on any   
groups
3)  I have routehog configured on both c7000's at 5000 and both complain   
of excessive
 routes from the mrouted 3.8.2 box.

Question:

I hope I'm not just being brain dead and missing something really simple   
here.

Any Ideas why no prunes on vif(2)?

If prunes where being sent on vif(2) when a group is joined how would
the rpf calculation decide which virtual route to use?

Can you configure mrouted to have a preferred vif (because one is over
your 4.5Mbit link with one unicast hop and the other over a slower link   
with
several unicast hops (my failover link)?

If the two tunnels ended on a c7000 could IOS be configured similarly?

I hope I haven't just missed this if it has been already covered in the   
group.
Maybe DVMRP just isn't ready for this yet....

Any and all replies welcome.....

 --mikej

---

From: Bill Fenner <[email-masked]>
Date: Thu, 11 Apr 1996 13:10:13 PDT

In message <[email-masked]> you write:
>when a group is joined how would

By the metric of the routes advertised.  If the metric is the same, then
via a tiebreaking algorithm.

>with several unicast hops (my failover link)?

Make the metric on the failover link one higher than the sum of the metrics
of all the links that it is the failover for.

>If the two tunnels ended on a c7000 could IOS be configured similarly?

Yes; the "ip dvmrp metric-offset <increment>" command is the parallel of
the "metric n" in the mrouted config file.

  Bill