OS: CentOS release 5.7 (Final) Net-SNMP: net-snmp-126.96.36.199-14.el5_7.1 (from RPM)
Periodically my NMS notifies me that SNMP has gone down on this machine. The service is restored in between 10 to 30 minutes. My NMS also pings and check SSH and those services are not affected during the SNMP outage.
SNMPD log file shows that it is working and apparently receiving packets (either from local agents from 127.0.0.1 or from my NMS at 172.16.37.37) however attempting to snmpwalk locally or from the NMS system fails with a timeout.
I have 7 of these servers running mixture of CentOS 5.7 and RHEL 5.7 with this specific version of Net-SNMP installed from RPM - none of them have this issue except this one. 5 of the machines (including the NMS system and this problem server) are in the same rack connected using one switch.
Restarting SNMPD does not fix the issue - it clears up by itself eventually. Any suggestions where I can begin diagnosing the issue? It's a closed subnet so IPTables is not used. SNMPD config below:
# Following entries were added by HP Insight Management Agents at # Tue May 15 10:58:17 CLT 2012 dlmod cmaX /usr/lib64/libcmaX64.so rwcommunity public 127.0.0.1 rocommunity public 127.0.0.1 rwcommunity 3adRabRu 172.16.37.37 rocommunity 3adRabRu 172.16.37.37 rwcommunity 3adRabRu 172.16.37.36 rocommunity 3adRabRu 172.16.37.36 trapcommunity callmetraps trapsink 172.16.37.37 callmetraps trapsink 172.16.37.36 callmetraps syscontact Lukasz Piwowarek syslocation Santiago, Chile # ---------------------- END -------------------- agentAddress udp:161 com2sec rwlocal default public com2sec rolocal default public com2sec subnet default 3adRabRu group rwv2c v2c rwlocal group rov2c v2c rolocal group rov2c v2c subnet view all included .1 access rwv2c "" any noauth exact all all none access rov2c "" any noauth exact all none none