Additional Ipsec Vpn Topics; Sa Life Time; Ipsec High Availability - ZyXEL Communications ZyWall 5 Series User Manual

ZyWALL 5/35/70 Series User's Guide

18.4 Additional IPSec VPN Topics

This section discusses other IPSec VPN topics that apply to either IKE SAs or IPSec SAs or
both. Relationships between the topics are also highlighted.

18.4.1 SA Life Time

SAs have a lifetime that specifies how long the SA lasts until it times out. When an SA times
out, the ZyWALL automatically renegotiates the SA in the following situations:
• There is traffic when the SA life time expires
• The IPSec SA is configured on the ZyWALL as nailed up (see below)
Otherwise, the ZyWALL must re-negotiate the SA the next time someone wants to send
traffic.
Note: If the IKE SA times out while an IPSec SA is connected, the IPSec SA stays
connected.
An IPSec SA can be set to nailed up. Normally, the ZyWALL drops the IPSec SA when the
life time expires or after two minutes of outbound traffic with no inbound traffic. If you set the
IPSec SA to nailed up, the ZyWALL automatically renegotiates the IPSec SA when the SA
life time expires, and it does not drop the IPSec SA if there is no inbound traffic.
Note: The SA life time and nailed up settings only apply if the rule identifies the
remote IPSec router by a static IP address or a domain name. If the Remote
Gateway Address field is set to 0.0.0.0, the ZyWALL cannot initiate the tunnel
(and cannot renegotiate the SA).

18.4.2 IPSec High Availability

IPSec high availability (also known as VPN high availability) allows you to use a redundant
(backup) VPN connection to another WAN interface on the remote IPSec router if the primary
(regular) VPN connection goes down.
In the following figure, if the primary VPN tunnel (A) goes down, the ZyWALL uses the
redundant VPN tunnel (B).
332 Chapter 18 IPSec VPN