Any issues on 3750 SVIs and HSRP?

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Jun 2nd, 2008
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Hi everyone,

I'm running HSRP on SVIs on two 3750 switches, the switches are connected together via a l2 etherchannel for HSRP, and a L3 connection. The switches are functioning as mostly layer three switches otherwise running OSPF.

When I go to a downstream router, that has two equal paths to the 3750s and ping the HSRP primary and virtual IP, everything works fine. But when I try to ping the secondary interface, the ping fails with .u.u.u.

The ping results look like a routing problem. I know OSPF will load balance from the upstream router to the HSRP subnet. But I still kind of confused why the router can't resolve this. In other designs I costed the links so OSPF always pointed at the primary HSRP device, and the router basically had only one route (to the primary). And this may be my issue, but I was wondering if it might be an issue with switches running HSRP on SVI's. I noticed the configuration support/syntax is rather limited on 3750s.

Any thoughts? Thanks!

Karl Solie

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Ryan Carretta Tue, 06/03/2008 - 00:18
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Hi Karl,

The u's in your ping failure signify that one of the routers along the way received packets to which the destination network was unreachable. If I were you, I'd track that router down and find out why it can't reach the destination network. Alternatively, its possible that the packets shouldn't even be headed off to that device in the first place. If that's the case, you of course would need to find out which device is making that routing decision.

It doesn't sound like this is an HSRP issue specifically, but more likely a routing issue.

ksolie Tue, 06/03/2008 - 05:39
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Thanks, I found the problem this morning. The U's should have tipped me off sooner, but it just didn't register.

It was a spoofing filter, they had put on the SVIs, ya I know...daaaa.

Anyway thanks for the help, problem resolved...



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