3560 12.2 SNMP timeout mid-query / SNMP over TCP

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Sep 13th, 2009
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we have a setup where our monitoring box has to go through a linux box to get to 3560 to get snmp data, so i have a DNAT setup.

For some strange reason snmpwalk always times out on the same spot.

Right after

IF-MIB::ifHCOutBroadcastPkts.10152 = Counter64: 0

And before

IF-MIB::ifLinkUpDownTrapEnable.1 = INTEGER: enabled(1)

every single time.

snmpwalk -t 60 -v2c udp:linux_box:16108 -c community

(port 16108 DNAT'd to 161/udp)

everything works fine if i go to the switch directly

I figured i could use snmp over tcp, but it does not look like this switch even supports it...

does anyone know how to enable this?


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Joe Clarke Sun, 09/13/2009 - 20:43
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SNMP over TCP is not supported. This sounds like some kind of buffer problem with Linux's DNAT module.

Since it looks like you're using net-snmp, you might try using its SNMP Proxy capabilities instead of DNAT. You just need to run the net-snmp snmpd on the Linux box.

See http://net-snmp.sourceforge.net/wiki/index.php/Snmpd_proxy on how to configure the proxy.

solefald Tue, 09/15/2009 - 07:31
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thank you so much! this solved my problem!


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