This KB explains the SNMP MIB OID used to retrieve the number of routes for each VRF instance.

As a general rule, you should use the SNMP MIB Explorer to search for the appropriate SNMP MIB OID that provides the information you want to retrieve.

However, it is not always obvious which specific information shown in a show command corresponds to a particular SNMP MIB OID. Therefore, actual verification is required. An example is provided below for reference.

For retrieving the number of routes per VRF instance the following OID is useful.

mplsL3VpnVrfPerfCurrNumRoutes
1.3.6.1.2.1.10.166.11.1.3.1.1.3

Example;

user@mx240> show snmp mib walk mplsL3VpnVrfPerfCurrNumRoutes
mplsL3VpnVrfPerfCurrNumRoutes.3.48.48.50 = 17
mplsL3VpnVrfPerfCurrNumRoutes.3.48.48.51 = 11
mplsL3VpnVrfPerfCurrNumRoutes.3.48.48.52 = 11
--- snip ---

user@mx240> show snmp mib walk 1.3.6.1.2.1.10.166.11.1.3.1.1.3
mplsL3VpnVrfPerfCurrNumRoutes.3.48.48.50 = 17
mplsL3VpnVrfPerfCurrNumRoutes.3.48.48.51 = 11
mplsL3VpnVrfPerfCurrNumRoutes.3.48.48.52 = 11
--- snip ---

user@mx240> show snmp mib walk mplsL3VpnVrfDescription
mplsL3VpnVrfDescription.3.48.48.50 = 001
mplsL3VpnVrfDescription.3.48.48.51 = 002
mplsL3VpnVrfDescription.3.48.48.52 = 003
--- snip ---

user@mx240> show configuration | display set | match instance | match description
set routing-instances 001 description 001
set routing-instances 002 description 002
set routing-instances 003 description 003
--- snip ---

user@mx240> show route summary
--- snip ---
001.inet.0: 12 destinations, 17 routes (10 active, 0 holddown, 4 hidden)
              Direct:      2 routes,      2 active
               Local:      3 routes,      3 active
                 BGP:     11 routes,      4 active
              Static:      1 routes,      1 active

002.inet.0: 8 destinations, 11 routes (8 active, 0 holddown, 2 hidden)
              Direct:      2 routes,      2 active
               Local:      3 routes,      3 active
                 BGP:      6 routes,      3 active

003.inet.0: 8 destinations, 11 routes (8 active, 0 holddown, 2 hidden)
              Direct:      2 routes,      2 active
               Local:      3 routes,      3 active
                 BGP:      6 routes,      3 active