ZyWALL 5/35/70 Series User’s Guide
Figure 232 H.323 ALG Example
Signaling session over
TCP port 1720
Audio session using RTP
•With multiple WAN IP addresses on the ZyWALL, you can configure different firewall and port forwarding rules to allow incoming calls from each WAN IP address to go to a specific IP address on the LAN (or DMZ). Use policy routing to have the H.323 calls from each of those LAN or DMZ IP addresses go out through the same WAN IP address that calls come in on. The policy routing lets the ZyWALL correctly forward the return traffic for the calls initiated from the LAN IP addresses.
For example, you configure firewall and port forwarding rules to allow LAN IP address A to receive calls through public WAN IP address 1. You configure different firewall and port forwarding rules to allow LAN IP address B to receive calls through public WAN IP address 2. You configure corresponding policy routes to have calls from LAN IP address A go out through WAN IP address 1 and calls from LAN IP address B go out through WAN IP address 2.
Figure 233 H.323 With Multiple WAN IP Addresses
•When you configure the firewall and port forwarding to allow calls from the WAN to a specific IP address on the LAN, you can also use policy routing to have H.323 calls from other LAN or DMZ IP addresses go out through a different WAN IP address. The policy routing lets the ZyWALL correctly forward the return traffic for the calls initiated from the LAN IP addresses.
For example, you configure the firewall and port forwarding to allow LAN IP address A to receive calls from the Internet through WAN IP address 1. You also use a policy route to have LAN IP address A make calls out through WAN IP address 1. Configure another policy route to have H.323 calls from LAN IP addresses B and C go out through WAN IP address 2. Even though only LAN IP address A can receive incoming calls from the Internet, LAN IP addresses B and C can still make calls out to the Internet.
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