OS: CentOS release 5.7 (Final) Net-SNMP: net-snmp-5.3.2.2-14.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