Disable snmpd native ipCidrRouteTable implementation (#675)

The SNMP subagent implements ipCidrRouteTable. If there is no nexthops
for default route, ie. switch isolated, the SNMP subagent will response
'no instance'. Then snmpd will response kernel routes, which include
non-front panel interfaces. To remove snmpd native implementation, we
only expose SNMP subagent's implementation.

dockers/docker-snmp-sv2/supervisord.conf

@@ -20,7 +20,7 @@ stdout_logfile=syslog
 stderr_logfile=syslog
 
 [program:snmpd]
-command=/usr/sbin/snmpd -f -LS4d -u Debian-snmp -g Debian-snmp -I -smux,mteTrigger,mteTriggerConf,ifTable,ifXTable,inetCidrRouteTable,ip -p /run/snmpd.pid
+command=/usr/sbin/snmpd -f -LS4d -u Debian-snmp -g Debian-snmp -I -smux,mteTrigger,mteTriggerConf,ifTable,ifXTable,inetCidrRouteTable,ipCidrRouteTable,ip -p /run/snmpd.pid
 priority=3
 autostart=false
 autorestart=false