SNMP walk using management interface IP address, which is a part of mgmt_junos routing instance, fails with the message, ' SNMPD_AUTH_FAILURE'.

Example:

user@ptx10001> show configuration snmp
community testcommunity {
    routing-instance mgmt_junos;
}
routing-instance-access;

mgmt_junos.inet.0: 3 destinations, 3 routes (3 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
 
0.0.0.0/0          *[Static/5] 00:33:29
                    >  to 10.219.36.1 via re0:mgmt-0.0
10.219.36.0/26     *[Direct/0] 00:33:29
                    >  via re0:mgmt-0.0
10.219.36.14/32    *[Local/0] 00:33:29
                       Local via re0:mgmt-0.0

When performing SNMP walk with only community name fails with the error below. However, the same SNMP walk command is successful on versions prior to Junos 20.3R2-EVO.

Example:
Note: Does not work on version 20.3R2 and above.

Performed SNMP walk <routing_instance _name> @ <community> as shown below, but it polls only the outputs limited to the routing instances.

Example:

From Junos version 20.3R2-EVO, SNMP walk will be successful only when using @ <community_name> . It provides information about all the instances including the default instance. 

It is recommended to add the " @ " symbol before community name. 

Example: