ISA Server 2004 stops forwarding traffic between networks and the Internet

Microsoft Internet Security and Acceleration (ISA) Server 2004 may not forward traffic between internal networks and the Internet.

This issue occurs if the internal network is not defined correctly in ISA Server.

The multi-networking design in ISA Server uses networks to represent one or more IP address ranges that can be reached from a network adapter on the ISA Server computer.

A network adapter can only be associated with a specific network. All IP addresses that can be reached from a network adapter must be defined as part of that network. It is especially important that remote subnets that are reachable through a router are correctly added to a network definition. Otherwise, these addresses are considered to be spoofed.

To resolve this issue, correctly define all the IP addresses in the network in ISA Server.

For more information about how to configure networks in ISA Server 2004, visit the following Microsoft Web site:For more information about how to troubleshoot specific issues in ISA Server 2004, visit the following Microsoft Web site: