[c-nsp] 7200 T1 Aggregator - ~30-40 LSA events/sec. Normal?

[Matt Stockdale]

My initial investigation with flood debug shows that this router is
receiving this LSA on fa0/0 from both the DR and the BDR, and sending
out about 170 Type 2 Acks back out the same interface to the multicast
ospf address within 5 seconds.

It also shows that the "Advertising Router" from the flooding LSA's just
isn't sending these out - I watched for 2 or 3 minutes and didn't see it
send this. (Which makes sense, the Link the LSA is describing is
stable.)

Since this router has only one ethernet interface, and that
interface/network is the only one OSPF is running on (really for the
sole purpose of advertising the T1 netblocks to the rest of our
network), Why would it be sending out LSA's from another router? In
theory, any update that comes in over fa0/0 is going to every other host
on that network already. I guess my OSPF-fu is a little weak, but that
doesn't seem smart to me..

Matt

-----Original Message-----
From: Rodney Dunn [mailto:rodunn at cisco.com] 
Sent: Thursday, April 27, 2006 4:57 PM
To: Matt Stockdale
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] 7200 T1 Aggregator - ~30-40 LSA events/sec. Normal?

debug ip ospf flood


You can configure ip ospf flood-reduction if all the routers in the
network support DC.


On Thu, Apr 27, 2006 at 04:33:12PM -0400, Matt Stockdale wrote:
> Hmm. It looks like when I took a tcpdump sample earlier, I managed to 
> grab the LSA's for the static route during their normal retransmit. It

> looks like the ongoing flood of LSA's is coming from somewhere else, 
> and being passed along. I'll keep investigating.
> 
> Matt
> 
> On Thu, 2006-04-27 at 14:50 -0400, Matt Stockdale wrote:
> > Folks -
> > 
> >   I've just noticed that our 7206VXR, NPE-400, 12.1.19(E1), is 
> > sending out ~30-40 LSA packets per second on the ethernet port that 
> > is the only link to our core. Now, this router runs 4 channelized T3

> > cards for T1 aggregation, and redistributes static and connected (85

> > and 44 routes, repsectively). None of the downstream routers on the 
> > T1 are configured for OSPF. (at least, they shouldn't be), and the 
> > circuits aren't bouncing.
> > 
> >   A quick debug session shows that the LSA's are for the static and 
> > connected routes.
> > 
> >   Is this normal? I see that I can configure some LSA throttling, 
> > but it's hard to figure out the right value to throttle at if I'm 
> > not sure why this is happening in the first place..
> > 
> >   Flames pointing me to RTFM welcome, as long as the TFM is
specified.
> > 
> > Thanks in advance,
> >   Matt
> > 
> > --
> > Matt Stockdale
> > Network Engineer
> > Logicworks
> > 
> >   
> > _______________________________________________
> > cisco-nsp mailing list  cisco-nsp at puck.nether.net 
> > https://puck.nether.net/mailman/listinfo/cisco-nsp
> > archive at http://puck.nether.net/pipermail/cisco-nsp/
> > 
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net 
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/