Configuring how long L2TP maintains dynamic information
One can configure the LAC or the LNS to specify how long the router attempts to maintain dynamic destinations, tunnels, and sessions after they have been torn down. This destruct timeout aids debugging and other analysis by saving underlying memory structures of those destinations, tunnels, or sessions. Any specific dynamic destination, tunnel, or session may not be maintained for this entire time period if the resources must be reclaimed early to allow new tunnels to be established. To set the destruct timeout, include the destruct-timeout statement at the [edit services l2tp hierarchy level. Also one can set the timer in the range 10 through 3600 seconds; the default value is 300 seconds.