Score! Well said. Yes, one of the behaviours I've seen in
a confused ospf environment is pinging from a router (which has
multiple paths to a destination, with one or more paths broken)
and getting a pattern back like this:
!.!.!.!.!.!.
It's one of those "ah ha!" patterns that quickly helps
to zero in on the problem.
davec
> By default pings from a router are per-packet load-shared out the box (pings
> originate from process level, so they use the same round-robin selection
> criteria). If you ping from a device behind West-3 to the address given you
> should see that it is destination load-shared.
>
> David
>
> -----Original Message-----
> From: Martin Cooper [mailto:mjc@cooper.org.uk]
> Sent: Wednesday, January 03, 2001 6:09 AM
> To: cisco-nsp@puck.nether.net
> Subject: [nsp] OSPF equal-cost multipath
>
>
> We've been seeing some curious behaviour as a result of
> equal-cost connected routes for interfaces participating
> in HSRP being in the routing table. I have always been
> under the impression that per-prefix load-sharing was
> the default behaviour, unless doing process-switching,
> or unless explicitly configured on a per-interface basis
> under CEF switching.
>
> What we see is this, which suggests that what is in fact
> happening is per-packet load-sharing. Can anyone shed any
> light on what might be going on here - could it be a bug
> perhaps? If I try a TCP connection with packet debugging
> turned on, per-prefix load-sharing does appear to happen
> as expected. All the routers involved are running 12.0(8),
> and there doesn't appear to be anything in the release
> notes to suggest this is anything other than normal.
>
> 131.111.8.0/24 is a connected route on both cent-8 and
> down-3, and cent-8, down-3, and west-3 are all attached
> to a broadcast network, 131.111.2.0/24.
>
> route-west-3.cam.ac.uk>trace 131.111.8.46
>
> Type escape sequence to abort.
> Tracing the route to www.cam.ac.uk (131.111.8.46)
>
> 1 route-down-3.cam.ac.uk (131.111.2.9) 4 msec
> route-cent-8.cam.ac.uk (131.111.2.8) 0 msec
> route-down-3.cam.ac.uk (131.111.2.9) 4 msec
> 2 aquila.csx.cam.ac.uk (131.111.8.74) 0 msec * 0 msec
>
> M.
>
>
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