ZyXEL Communications ZyWALL 110 Handbook page 138

Figure 312 VPN > Branch Office VPN > Gateway > General Settings > Gateway Endpoints
The new Gateway Endpoint dialog box appears. Configure your Local Gateway identity as
4
WatchGuard's External IP Address (in the example, 172.100.30.63) and Remote Gateway
identity as your ZyWALL/USG's WAN IP Address (in the example, 172.101.30.73). Click OK.
Figure 313 VPN > Branch Office VPN > Gateway > General Settings > Gateway Endpoints
Then, go to VPN > Branch Office VPN > Gateway > Phase 1 Settings to select negotiation
5
Mode the same as your ZyWALL/USG's Phase 1 Settings. Make sure you enable both NAT
Traversa and Dead Peer Detection options if both options are enabled in the ZyWALL/USG.
Chapter 4 Create Site-to-Site VPN Tunnels
ZyWALL/USG Series User's Guide
138