I am running Forefront TMG 2010 and have it configured it for ISP Redundancy.The server has three NIC’s (LAN, ISP1 and ISP2) and ISP redundancy has been configured with gateways specified for both of the ISP connections.
Initially I only assigned the ISP1 NIC with a gateway as described in the following blog:
Everything worked fine but I started getting the following alerts:
ISP Redundancy – Missing Default Gateway – A default gateway is not defined on the network adapter associated with ISP connection ISP2.
After this I have tried also assigning a gateway to the ISP2 NIC.
This appears to work and has stopped the alerts, however when I run the Microsoft ISA Server Best Practices Analyser Tool I get the following warning:
Multiple default gateways are configured – More than one network adapter has a default gateway specified, or at least one network adapter has more
than one default gateway listed. Communication errors may occur if these default gateways point to different subnets.
Should only one of the NICs have a default gateway assigned and if so why is an alert being generated when the server is configured in this way?
“Should only one of the NICs have a default gateway assigned and if
so why is an alert being generated when the server is configured in this way?” – To use ISP-R, you should configure two default gateways for each NIC. Because two default gateways will only
confuse the machine which default gateway to use for a particular connection. For ISP-R configuration, you need to specify the default gateway in the wizard and not at the NIC.
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