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RE: HSRP or switch issue? [7:63768] posted 02/25/2003
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You might want to look up the following document on CCO:
Avoiding HSRP Instability in a Switching Environment with Various Routing
Platforms.
Looks like www.cisco.com/warp/public/619/8.shtml


> -----Original Message-----
> From: John Starta [mailto:john@xxxxxxxxxx]
> Sent: Tuesday, February 25, 2003 1:12 PM
> To: cisco@xxxxxxxxxxxxxx
> Subject: HSRP or switch issue? [7:63768]
> 
> 
> 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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