|All VLANS are connected to fastethernet 0/0,and both ISPs will be connected to fastethernet 0/1|
So what you're saying is:
fa0/0 = internal interface
fa0/1 = external interface
I'm not sure if you can actually connect two separate external connections to one interface of a router without using a switch. How had you planned on doing that exactly?
To my way of thinking, each external interface would be connected to a separate interface on the router (ie: fa0/1 = external 1 and fa0/2 = external 2)
Now my main question is how can i configure my cisco router to route traffic on the basis of source subnets.
I'm no authority on Cisco routers as we use teamed redundant OpenBSD servers for our firewalls here where I work. I do have a couple 2600's and one 2800 kicking around but I really haven't had time to play with them.
Drawing from my own experience though, I would do something as follows (going with my "1 interface per external connection" theory)
fa0/1 = external 1
IP = 172.30.0.250
fa0/2 - external 2
IP = 172.30.7.250
Then your IP configuration for subnets 0-6 would have the default gateway IP of 172.30.0.250 (external 1) and for subnets 7-15 would have default gateway 172.30.7.250 (external 2)
You would only need to route between subnets.....the default gateway used in each subnet would be what you use to control which interface the external traffic for that subnet would flow through.