UDP not responing on a c2350

Unanswered Question
Dec 10th, 2009
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Note sure if I am putting this query in the right location, so sorry in advance.

I have four c2350 switches and for some reason two of them didn't seem to like to respond to SNMP request from our monitoring software (Cacti). So I did some testing on it and I boiled it down to the switches didn't seem to want to respond to UDP traffic. However with some debugs I saw that they did recieve the traffic, just never responded to it. One of the switches is not yet in production and I ended up doing a reload on it and it started to work. However, the other one is in production and I can't reload it till a maintaince window. That's fine but I was wondering if anyone else had this problem, what causes it, and if there is a way to fix it with out reloading the switch. Any insite would be helpful.

Below is the UDP debug for a simple SNMP request for the switches uptime via Peassler SNMP Tester. As you can see Switch 1 responds to the UDP traffic it recieves but Switch 2 does not. All other UDP traffic seems to be the same way, I'll have rcvd/sent traffic on Switch 1 and only rcvd on Switch 2.

Switch 1 (Working):

Dec 10 16:04:40.470: UDP: rcvd src=, dst=, length=49
Dec 10 16:04:40.470: UDP: sent src=, dst=, length=52
Dec 10 16:04:40.479: UDP: rcvd src=, dst=, length=49
Dec 10 16:04:40.479: UDP: sent src=, dst=, length=52

Switch 2 (Not working):

Dec 10 16:04:15.841: UDP: rcvd src=, dst=, length=49
Dec 10 16:04:20.849: UDP: rcvd src=, dst=, length=49



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Ganesh Hariharan Sat, 12/26/2009 - 01:45
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Hi Adam,

Really starnge think can you provide the following details:-

1) Switch version with ios details

2) Any community string is cnonfigured between switch and snmp server.If yes just delete the configuration in swicth and reconfigure then check is it listening to snmp server or not.

3) And Can you test the same think with other devices other than switch for snmp test is the behaviour is same or different.




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