From: Tony H. (aamercado31@xxxxxxxxx)
Date: Fri Aug 09 2002 - 01:31:27 GMT-3
Hi
Most routing loops occur on distance vector in regards
to redistribution and/or Admin Dist issues..here is my
check list:
rip/igrp
bgp
eigrp
ospf
So basically you need to primarily worry about
rip/igrp. With that said, here are the common
commands:
Rip/Igrp - show ip route to look for "possibly down"
message would indicate a routing loop
BGP - Show ip bgp to watch if the bgp table #
increments would indicate loop
Eigrp - DUAL algorithm makes it pretty good at
avoiding loops...so haven't come across a good "spot
this" command
OSPF - Link State makes it pretty good at avoiding
loops..also haven't come across a good command to spot
this.
In general, show ip traffic to spot incrementing "bad
hop counts" would indicate loops.
Finally, once you isolate the loop, you can use the
trace command to follow the routing path and via
process of elimination find the source of the loop.
HTH
--- "Howard C. Berkowitz" <hcb@gettcomm.com> wrote:
> At 1:50 AM +0000 8/7/02, Gordan Chan wrote:
> >Hi,
> >
> >I am thinking how to detect route loop.
>
>
> Well, a good start for you to understand routing
> loops is to define
> what you consider a routing loop to be. There are
> several kinds, both
> permanent and transient. There isn't one kind and
> one problem.
> There are both mechanisms that prevent them, and
> mechanisms that
> break them once formed -- or counter the effects of
> them.
>
> >
> >Could someone share the checklist/method on the
> detection and how to
> >prevent it?
> >
> >Thank you very much.
> >
> >Chan
>
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