[nsp] HSRP or switch issue?

[Todd, Douglas M.]

John:

Possible issues:
1) There are a few issues that we ran across with someworkstations sending
out multicast traffic using address 224.0.0.2.
I am seeing if I can dig up the information or you.
2) Router is seeing itself and its hellos, mac etc. You might have a
bridging loop somewhere.

Check for any indication of a bridging loop. This will definitely cause the
error you are seeing. If you have not made any changes recently using
multicast then you are not going to see the issue w/#1.

Just some ideas.

==DMT>


> -----Original Message-----
> From:	John Starta [SMTP:john at starta.org]
> Sent:	Tuesday, February 25, 2003 1:51 PM
> To:	cisco-nsp at puck.nether.net
> Subject:	[nsp] HSRP or switch issue?
> 
> I'm currently experiencing an oddity with multicast traffic like HSRP that
> 
> I'm looking for some ideas on. For simplicity the network design consists 
> of 2 Cisco 3640 routers running HSRP between them connected to a single 
> Extreme [Black Diamond] switch. Basically...
> 
>             extreme switch
>               |       |
>               |       |
>              rtr1    rtr2
> 
> Normally everything works just fine, but periodically -- in time, not 
> quantity -- HSRP indicates via the %HSRP-4-DUPADDR message that I have a 
> duplicate [IP] address. (The quantity of the messages indicating the 
> duplicate IP address ranges from half dozen to nearly a hundred. The time 
> between messages closely matches the HSRP HELLO interval.)
> 
> When I receive these messages, on the active HSRP router for instance,
> they 
> indicate the duplicate address as being the physical interface IP address 
> of the active HSRP router with the source MAC address as the virtual MAC 
> [address] of the active HSRP router. Receipt of these %HSRP-4-DUPADDR 
> messages indicating the duplicate as itself suggests an issue with 
> multicast -- a loop of sorts whereby the switch copies the multicast 
> announcement [back] to the same switch port it originated. Keep in mind 
> that there are no interface or HSRP state changes so the messages probably
> 
> aren't coming from the standby HSRP router. (Especially since the
> indicated 
> duplicate IP address is that of the physical interface on the active HSRP 
> router, not the virtual IP.)
> 
> I did some poking around on Extreme's web site and they indicate an issue 
> with HSRP in an earlier version of code, but that is/was fixed in the 
> version being used.
> 
> Have anybody run into this before? Ideas regarding cause? I don't have 
> access to the switch since it belongs to the customer.
> 
> .,
> 
> 
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