3560G stops responding to SNMP when de/reconnecting ports

[carlbackstrom]

I have two 3560G 24p switches, connected to each other via two links in Etherchannel. From one of the switches i retrieve SNMP info about port status and traffic for these two ports. That works great, until i pull out random cable. The switch responds with ifOperStatus = 2 and traffic drops to zero for that partikular port, as it should. But a some of seconds later it stops responding to my snmp reguests for ~ 5 seconds. That causes problems as my watchdog sets an alarm as it thinks the connection to the switch has been lost. (It checks switch uptime is increasing all the time)

If I set a delay on the watchdog on my monitoring system of 15sec, it works. But it ain't that nice to have a delay of 15 sec if the connection really is lost.

Any ideas on what to look for?  I'm fairly new into managed switches so advices are appreciated!                

[Peter Paluch]

Hello Carl,

A couple of questions:

1. When you say you pull a random cable, is it a random cable from the EtherChannel, or just any cable?
2. How often do you perform SNMP polls on your devices?
3. What kind of STP are you running between these two devices?
4. If you performed a continuous ping on the switch that stops responding to SNMP polls and pull a cable, would the continuous ping also exhibit packet losses? Please use a short-timed ping, for example, sending a ping each 500ms with the timeout also being set to 500ms - 1000ms.

Thank you!

Best regards,

Peter

[carlbackstrom]

Thank you for fast reply,

1. It's one of the Etherchannel cables, as these are the two I want to monitor.

2. I have set the SNMP agent to poll the switch with 1 sec interval

3. Not really sure, but I have not changed the default settings for STP(If I read the manual correct the default is PVST+ ?) Tried uplinkfast but no difference.

4. If connect my computer to switch nr1 (The one I'm getting SNMP data from) I get no package losses what so ever. If i connect to the other switch but still ping nr1, I only loose a couple of packets just in the disconnection moment. Which I suppose is normal?

Thanks again!

Best regards,

Carl