[c-nsp] Reaction to forwarding failure...

[Rodney Dunn]

I had an idea and wondered how common this would
be and how much customers would like it.

The idea is how to react on a known failure
type for a redundant design.

Let's say you have this:

   COREA    COREB
     |        |  
    L3A      L3B 
     |        | (HSRP)
  Access layer switches



Pretty typical design if you are not doing L3 all the way to
the access.  Now let's say you have some form of hardware
forwarding failure on the L3A (l3 switch) switch.  With the
failure there is a chance you punt the packet to process
level and overrun the CPU.  Assume L3A is HSRP primary.

What about if there were a configurable option that for
known failure conditions you could have all routing
disabled for the routing protocols and also have HSRP
disable itself?  That way you would failover to the
redundant path both ingress/egress to the core.

Clearly this doesn't apply to all designs.  If you only
have a single path you would want that path to continue
to pass the traffic that it can.  You could still reach
L3A from COREA by telnetting to the directly connected
ip address.

Thoughts?

Rodney