Our current network consists of an internal network connected to a router and to an external DSL network for Internet access. We also have a completely separate network for our servers connected to a separate router and then to multiple T1 lines for Internet access.
What I'm trying to do is to use one ISA server for both of these networks. But I'm having a very hard time with this because we're going to have one Internal Network, and one parameter network (for the servers), and TWO separate external networks.
So my question is, how can I setup ISA to route all external traffic going from the internal network through the DSL router, and all external traffic going from the parameter network through the T1 router???
I'm planning to use 4 nic cards. one for the Internal network, one for parameter (servers) network, one going to the DSL router, and another one going to the T1 router.
ISA Server Does Not Support Multiple External Interfaces Problem: ISA Server does not support multiple external connections to the Internet. Cause: ISA Server does not support configuring multiple connections on the External network adapter. Solution: No workaround. There are a number of third-party products that may provide a solution. For more information, see High Availability and Load Balancing at the Windows Server System Web site.
Why couldn't a single ISA Server be implemented routing between it's internal networks and external networks and then put the PBR router OUTSIDE the ISA server? Since you haven't NAT'd the connections, you could PBR based on sources address, then NAT the connections through the PBR router to the different internet routers??? You would need a PBR router with one ethernet interface for the inside and one for each internet router (unless you used a dot1q trunk to a switch connecting all the internet routers)