Q: Firewall l2tp session detection mechanism
A: L2tp session firewall detection mechanism, based on the following two latitudes:
1. PPP keepalive , by setting the timer hold decide the detection time, three times if no response is received to the end, and it will remove the corresponding l2tp session.
2. Two minutes of business checks, if there is no packet exchange within two minutes of any firewall will delete l2tp session.