To use SNMP to get the amount of time since the X-Series chassis was last initialized, use the HOST-RESOURCES-MIB (host -> hrSystem -> hrSystemUptime). The OID is .18.104.22.168.22.214.171.124.1.0.
# snmpget -v 1 -c public 172.16.1.1 .126.96.36.199.188.8.131.52.1.0
The uptime value can also be accessed from Linux by using either of the following commands: # uptime# cat /proc/uptime
Do not confuse this MIB with the sysUpTime
MIB from RFC1213 (RFC1213 -> system -> sysUpTime), OID .184.108.40.206.220.127.116.11.0. This MIB refers to the time since the network management portion of the system was re-initialized. It indicates when the SNMPagent was started, not when the system itself last booted.
# snmpget -v 1 -c public 172.16.1.1 .18.104.22.168.22.214.171.124.0
This is a Linux standard.