Forefront TMG cannot locate a route to the remote site. As a result, a connection cannot be established. To establish the IPsec site-to-site connection, you must update the routing table.

I'm setting up a site-to-site IPSEC tunnel between Forefront TMG 2010 and Cisco ASA 5512-X. The tunnel initiates fine when there is an interesting traffic coming from the ASA side. Once the tunnel is initiated, the traffic flows both ways.

I can't seem to be able to get the Forefront to initiate the tunnel. On server restart, the following message gets logged in the event log:

"Forefront TMG cannot locate a route to the remote site. As a result, a connection cannot be established. To establish the IPsec site-to-site connection, you must update the routing table."

What exactly do I need in the routing table for Forefront to be able to initiate the tunnel?