From: Todd, Douglas M. (DTODD@PARTNERS.ORG)
Date: Mon Apr 23 2007 - 21:50:02 ART
Ok I'll byte :)
Here is what my interpretation will be of the data you have provided:
1) If you have equal paths with equal costs, traffic will round robin between
the paths.
2) I am assuming that your bgp sessions using the local interface addresses and
not loopbacks.
3) Pending on your configuration: ip cef or fast switching your load balancing
will be minimal based on the destination
prefix. Thus you should balance once as long as the cef entry remains
for that destination.
4) To help remove the obvious bgp messages you can create an acl to remove these
from your debugging.
debug ip routing <acl>
5) You could also run a debug on the protocol you are running. This will help
concentrate your efforts and not have your sifting through other routing
protocols which are not pertient to what you are doing. Ie., if I am
redistributing from ospf->rip I may turn on rip debugging.
6) I would state that this is normal output for the debug for changes to the
FIB/RIB.
My 2 Bits:
However, I find it easier to do a (for example) sh ip rip data review what is
being redistributed. The same goes for the ospf database. Doing a sh ip os da
<router>/<network>/<summary> will help you understand what routes get placed
where. If you have equal cost paths they will showup in the database.
Each to their own..
Just my thoughts.
DMT
-----Original Message-----
From: nobody@groupstudy.com on behalf of CCIEwnaB
Sent: Mon 4/23/2007 6:54 PM
To: Cisco certification
Subject: Fwd: Question about debug ip route output
So no repsonses on this. Is that because you're trying to reproduce it...or
is this shocked amazement at yet another long question with an obvious
answer?
If it's the later, please enlighten me ;)
---------- Forwarded message ----------
From: CCIEwnaB <cciewnab@gmail.com>
Date: Apr 21, 2007 5:49 PM
Subject: Question about debug ip route output
To: Cisco certification <ccielab@groupstudy.com>
Smart peeps,
Like many others on GS I have gotten in the habit of using "debug ip routing"
through most of the lab. I like that I get instant feedback if I accidently
kill a route or two, and enjoy seeing them pop in when adding a network
statement or redistribution. That being said I have noticed something in
many labs related to OSPF load balancing and just want to be sure I'm not
habitually screwing something up.
When I have two paths to the same destination and am equal cost load
balancing to that destination, I've noticed that any time I have traffic
running (ping for example) across the load balanced link (with debug ip
routing enabled) I see a message noting an RDB change from Path A to Path B.
If I ping again it swaps from B to A.
When I do a show ip route 1.2.3.4 I see that I'm load balancing on 2 paths
with a traffic share count of 1 on each path, which makes sense.
I guess I just want to be sure this output is normal and that I haven't
missed anything. It's especially abnoxious when a BGP peering session is
running acros the load balanced path. The TCP session results in a steady
stream of these messages.
Thanks in advance,
wnaB
This archive was generated by hypermail 2.1.4 : Tue May 01 2007 - 08:28:37 ART