VPP service fails to start when we restarting it having a pppoe session established on the same interface:
```
an 14 07:10:44 vyos netplugd[4898]: eth1: state ACTIVE flags 0x00011043 UP,BROADCAST,RUNNING,MULTICAST,10000 -> 0x00001002 BROADCAST,MULTICAST
Jan 14 07:10:44 vyos netplugd[8782]: /etc/netplug/netplug eth1 probe -> pid 8782
Jan 14 07:10:44 vyos netplugd[4898]: eth1: can't get flags: No such device
Jan 14 07:10:44 vyos accel-pppoe[8722]: pppoe: delete link event received, stopping the service on: eth1 ifindex 22
Jan 14 07:10:44 vyos accel-pppoe[8722]: pppoe_session0:test: pppoe: issue to terminate PPPoE session with hook
Jan 14 07:10:44 vyos accel-pppoe[8722]: pppoe_session0:test: ppp_chan_send: short write -1, excpected 6
Jan 14 07:10:44 vyos netplugd[4898]: eth1: can't get flags: No such device
Jan 14 07:10:44 vyos netplugd[4898]: eth1: can't get flags: No such device
Jan 14 07:10:44 vyos netplugd[4898]: eth1: can't get flags: No such device
Jan 14 07:10:44 vyos netplugd[4898]: eth1: can't get flags: No such device
Jan 14 07:10:44 vyos netplugd[4898]: eth1: can't get flags: No such device
Jan 14 07:10:44 vyos netplugd[4898]: eth1: state PROBING pid 8782 exited status 256
Jan 14 07:10:44 vyos netplugd[4898]: Could not bring eth1 back up
Jan 14 07:10:44 vyos netplugd[4898]: eth1: can't get flags: No such device
Jan 14 07:10:44 vyos systemd[1]: vpp.service: Main process exited, code=exited, status=1/FAILURE
Jan 14 07:10:44 vyos netplugd[4898]: eth1: can't get flags: No such device
Jan 14 07:10:44 vyos netplugd[4898]: eth1: can't get flags: No such device
Jan 14 07:10:44 vyos systemd[1]: vpp.service: Failed with result 'exit-code'.
Jan 14 07:10:44 vyos systemd[1]: vpp.service: Triggering OnFailure= dependencies.
Jan 14 07:10:44 vyos systemd[1]: vpp.service: Consumed 5min 30.507s CPU time.
Jan 14 07:10:44 vyos systemd[1]: Starting Restart VPP on failure...
Jan 14 07:10:44 vyos netplugd[4898]: eth1: can't get flags: No such device
Jan 14 07:10:44 vyos netplugd[4898]: eth1: can't get flags: No such device
Jan 14 07:10:44 vyos netplugd[4898]: eth1: can't get flags: No such device
Jan 14 07:10:47 vyos vyos-configd[821]: Received message: {"type": "init"}
Jan 14 07:10:47 vyos accel-pppoe[8722]: pppoe_session0:test: ppp_chan_send: short write -1, excpected 6
Jan 14 07:10:47 vyos vyos-configd[821]: config session pid is 8811
Jan 14 07:10:47 vyos vyos-configd[821]: config session sudo_user is root
Jan 14 07:10:47 vyos vyos-configd[821]: commit_scripts: ['vpp']
Jan 14 07:10:47 vyos vyos-configd[821]: Received message: {"type": "node", "last": true, "data": "/usr/libexec/vyos/conf_mode/vpp.py"}
Jan 14 07:10:47 vyos vyos-configd[821]: eth1 still in use by the PPPoE server. Disable PPPoE control-plane
Jan 14 07:10:47 vyos vyos-configd[821]: integration with VPP before proceeding.
Jan 14 07:10:47 vyos vyos-configd[821]: [vpp] eth1 still in use by the PPPoE server. Disable PPPoE control-plane
Jan 14 07:10:47 vyos vyos-configd[821]: integration with VPP before proceeding.
Jan 14 07:10:47 vyos vyos-configd[821]: scripts_called: ['vpp']
Jan 14 07:10:47 vyos vyos-configd[821]: Sending reply: ERROR_COMMIT with output
Jan 14 07:10:48 vyos systemd[1]: opt-vyatta-config-tmp-new_config_8811.mount: Deactivated successfully.
Jan 14 07:10:50 vyos accel-pppoe[8722]: pppoe_session0:test: ppp_chan_send: short write -1, excpected 6
Jan 14 07:10:51 vyos python3[8811]: Traceback (most recent call last):
Jan 14 07:10:51 vyos python3[8811]: File "/usr/libexec/vyos/reset_section.py", line 119, in <module>
Jan 14 07:10:51 vyos python3[8811]: session.commit()
Jan 14 07:10:51 vyos python3[8811]: File "/usr/lib/python3/dist-packages/vyos/configsession.py", line 325, in commit
Jan 14 07:10:51 vyos python3[8811]: out = self.__run_command([COMMIT])
Jan 14 07:10:51 vyos python3[8811]: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Jan 14 07:10:51 vyos python3[8811]: File "/usr/lib/python3/dist-packages/vyos/configsession.py", line 252, in __run_command
Jan 14 07:10:51 vyos python3[8811]: raise ConfigSessionError(output)
Jan 14 07:10:51 vyos python3[8811]: vyos.configsession.ConfigSessionError: [ vpp ]
Jan 14 07:10:51 vyos python3[8811]: eth1 still in use by the PPPoE server. Disable PPPoE control-plane
Jan 14 07:10:51 vyos python3[8811]: integration with VPP before proceeding.
Jan 14 07:10:51 vyos python3[8811]: delete [ vpp ] failed
Jan 14 07:10:51 vyos python3[8811]: Commit failed
Jan 14 07:10:51 vyos systemd[1]: vpp-failure-handler.service: Main process exited, code=exited, status=1/FAILURE
Jan 14 07:10:51 vyos systemd[1]: opt-vyatta-config-tmp-new_config_8811.mount: Deactivated successfully.
Jan 14 07:10:51 vyos systemd[1]: vpp-failure-handler.service: Failed with result 'exit-code'.
Jan 14 07:10:51 vyos systemd[1]: Failed to start Restart VPP on failure.
Jan 14 07:10:51 vyos systemd[1]: vpp-failure-handler.service: Consumed 6.008s CPU time.
Jan 14 07:10:53 vyos accel-pppoe[8722]: pppoe_session0:: disconnected
```
Config:
```
set vpp settings interface eth1 driver 'dpdk'
set service pppoe-server interface eth1 vpp-cp
set service pppoe-server access-concentrator 'PPPoE-Server'
set service pppoe-server authentication local-users username test password 'test'
set service pppoe-server authentication mode 'local'
set service pppoe-server client-ip-pool PPPOE-POOL range '203.0.113.20-203.0.113.30'
set service pppoe-server default-pool 'PPPOE-POOL'
set service pppoe-server gateway-address '203.0.113.1'
```
To trigger failure:
```
sudo vppctl restart
```