Networking Question

[Konrad Neuwirth <konrad%mailathome.or.at@localhost>]

Dear reader, 

I have a question that has me stymied. We have a NetBSD 6.1 system that is 
connected to multiple networks; two of them are internet uplinks. One of them 
has low bandwidth but fixed IP numbers that we need to have services run on 
(and those services are actually on another host and we just do port 
forwarding). The other is the high bandwidth link, but with a dynamic IP 
number. 

I'm trying to get my head around how to properly configure this, but can't get 
it to work. Code to have multiple default gateways seems to no longer be there. 
But how can I have traffic that originates on one interface (because it comes 
in via that one connection) be routed back correctly via the low-bandwidth 
link, whereas other internet traffic goes the other way? 

Thank you very much,
 KonradD