In my test lab I have a small, inexpensive, unnamed router to create two subnets, 12.1.1.0 and 172.17.2.0. The router is configured in Router mode (not Bridge), and I have a bridge defined that joins the two interfaces these subnets are on.
This is for testing software that relies on UDP communications between hosts on different subnets in large networks. Part of the requirements for these hosts is that they send 'route requests' to several broadcast addresses (one of which is the one the sending host lives on), so that the target host, regardless of subnet, will see the request and respond with a unicast reply. Thereafter the hosts communicate via unicast.
The configuration I'm using works fine as long as all hosts are configured with unicast targets, but a UDP broadcast for any foreign subnet dies on the receiving interface on the router.
In a real production environment, I can send a route request from (say) 12.1.1.15 to 172.17.2.255, and the network will relay the request packet intact to the correct subnet. Is there a general rule for routers that would cover this situation? Any technique will work as long as the host endpoints can successfully send broadcast traffic to other subnets. I don't have access to high-end routers.
