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Wednesday, February 10, 2016

Timeout: No Response from - Trying to SNMPWALK a Juniper Router/Switch with Routing-Instances Configured

Problem:

I was trying to snmpwalk a juniper switch (EX4500) that has routing instance configured!
The SNMP client was only reachable from a specific routing instance on the switch. However, i could successfully ping the switch OAM IP from the snmp client.

For example:

Ping from the snmp client is OK:

SNMP CLIENT:~ # ping 10.0.1.170
PING 10.0.1.170 (10.0.1.170) 56(84) bytes of data.
64 bytes from 10.0.1.170: icmp_seq=1 ttl=63 time=1.13 ms
64 bytes from 10.0.1.170: icmp_seq=2 ttl=63 time=1.12 ms
64 bytes from 10.0.1.170: icmp_seq=3 ttl=63 time=1.43 ms


Ping from the switch in the Global routing instance is NOT OK:

> ping 10.0.43.18                                                     
PING 10.0.43.18 (10.0.43.18): 56 data bytes
ping: sendto: No route to host
ping: sendto: No route to host


Ping from the switch in VR-OAM routing instance is OK:

> ping routing-instance VR-OAM 10.0.43.18                             
PING 10.0.43.18 (10.0.43.18): 56 data bytes
64 bytes from 10.0.43.18: icmp_seq=0 ttl=63 time=1.235 ms
64 bytes from 10.0.43.18: icmp_seq=1 ttl=63 time=1.504 ms
64 bytes from 10.0.43.18: icmp_seq=2 ttl=63 time=1.878 ms
64 bytes from 10.0.43.18: icmp_seq=3 ttl=63 time=1.215 ms


And whenever i would run snmpwalk from my snmp server, i would get the message below:

SNMP CLIENT:~ # snmpwalk -v2c -c public 10.0.1.170
Timeout: No Response from 10.0.1.170

Solution:

In order to access MIB objects and perform SNMP operations for the routing-instances, SNMP v1 and v2c clients need to encode the routing-instance name in the community string in their SNMP requests. 


snmpwalk -v2c -c routing-instance-name@public x.x.x.x

Example:

SNMP CLIENT:~ # snmpwalk -v2c -c VR-OAM@public 10.0.1.170

SNMPv2-MIB::sysDescr.0 = STRING: afrsite1epcrtr01_switch
SNMPv2-MIB::sysObjectID.0 = OID: SNMPv2-SMI::enterprises.2636.1.1.1.2.44
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (644286429) 74 days, 13:41:04.29
SNMPv2-MIB::sysContact.0 = STRING: 
SNMPv2-MIB::sysName.0 = STRING: VR-OAM@EPC_RTR01
SNMPv2-MIB::sysLocation.0 = STRING: 
SNMPv2-MIB::sysServices.0 = INTEGER: 6
IF-MIB::ifNumber.0 = INTEGER: 272
IF-MIB::ifIndex.6 = INTEGER: 6

Problem Solved :-) 


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