After the L2TP tunnel failover is triggered (timeout or specific L2TP session or tunnel setup error message), a new tunnel spec in the list of available tunnel specs are selected. This tunnel selection mechanism can be controlled with CLI so that the new tunnel-spec is selected from the next preference level. Alternatively, the tunnel selection mechanism can be set to a mode where all the possibilities within the same preference are exhausted, tunnel specs on a higher preference level are tried.
configure router l2tp
configure service vprn <id> l2tp
next-attempt same-preference-level | next-preference-level
When all tunnels on a specific preference levels are denylisted, then the behavior depends on the configuration option as per the following:
next-attempt = next-preference
Only one tunnel spec from the current preference level is tried before switching to the next preference level.
next-attempt = same-preference
All tunnel specs are tried before switching to the next preference level.