With a default configuration, filtering of shmlog entries based on username on an L2TP network server (LNS) does not work. Filtering based on username is useful for troubleshooting unsuccessful L2TP subscriber login attempts on LNS because other filtering keys (tunnel-id, session-id, and ip-address) might not be available as the session is not established yet.

This article explains how to perform username filtering of shmlog entries for troubleshooting purposes.

The default behavior can be seen in the example below:

user@router> show subscribers
Interface             IP Address/VLAN ID                      User Name                      LS:RI
si-0/0/0.3221225472   192.168.1.1                             [email protected]                default:default

root@router> show shmlog entries logname all username [email protected]

root@router>

With the following additional configuration:

set system services subscriber-management overrides shmlog filtering enable

After reconnecting the L2TP session, the filtering based on username works:

root@router> show shmlog entries logname all username [email protected] | count
Count: 778 lines

root@router>

2021-12-03: Corrections made based on feedback