SNMP get-response is a broadcast packet?

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Apr 28th, 2008
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I have one 6509-E Sup720 what is sending its snmp get-responses out as a broadcast packet. Of course this it not allowing the switch to be monitored over the wan as the broadcasts are being dropped over the routed hops. Has anyone ran into this and how did you fix it. Rebooting switch would be very painful process as attached systems are production web environment. Thanks for any insight on this matter. BTW, I have other switch with identical hardware, IOS version etc and they are not doing this.

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Joe Clarke Mon, 04/28/2008 - 09:12
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Sounds like this could be CSCsk80935:


Occasionally, UDP traffic will be incorrectly send to the broadcast address, rather than to the correct unicast address.



The bug is fixed in 12.2(18)SXF12 and 12.2(33)SXH1

jasonmcl Mon, 04/28/2008 - 12:54
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I resolved the issue. After a ton of research and a deep inspection into the sh tech I determined that the fh_fd_snmp.proc process was where the issue originated. Upon further research I was able to figure out how to restart this process and bam snmp is now working again correctly. I would like Cisco's official response to my findings. We will update the code at our earliest convenience. It may however be helpful for other customers to know that this possible work around may help their situation as it has mine. Let me know your thoughts.

Joe Clarke Mon, 04/28/2008 - 13:06
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The bug actually deals with improper initialization of a bit mask variable. You probably could have restarted any process that touched this code path, and might have fixed the problem. It all has to deal with memory contents. An upgrade is the only guaranteed way to resolve the problem.

jasonmcl Mon, 04/28/2008 - 13:08
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excellent.. Thanks for the quick reply. I did read that as well. So at least I dont have to take down my switch and can upgrade during a normal maint. window. Thanks again!

rduke Wed, 06/18/2008 - 09:56
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I am glad I found this post because I have been having trouble determining why one of my 6513 switches is missing SNMP interface polls. If you have a workaround that works without having to reload the switch I would like to know how to do that. It is also very incovenient for me to upgrade this particular switch.




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