Can same subnet resides in different routers?

[jen-li]

I only have two subnets form isp. I want to use some ips on our dadicated router outside the firewall. Is it ok to use same subnet on different router?

[svermill]

If you subnet your subnet accordingly you can probably do it. You need a routing protocol with VLSM support (eigrp would be one choice for a small network). You might want to check out VLSM on CCO so you understand how to properly implement it for your given network. There is a hierarchy requirement that must be adhered to so it is impossible to say from your description whether you can do exactly what you are thinking of.

[r.crist]

Jen:

If you are referencing connecting more than one router to the same physical segment and assigning an IP address on the same network, then the answer is yes; you can connect single interfaces from multiple routers to the same subnet. If you mean using the same network address space behind two different routers, then the answer is no; you must use different subnets for each network. Someone else responded to your question with a reference to vlsm and eigrp. vlsm will allow you take the address space from your ISP and break it down further into multiple, smaller networks.

Although, I seem to remember a white paper from Cisco from several years ago that said that they supported discontiguous address space across a routed boundary... A vpn tunnel would also allow you to extend address space to multiple segments, but this would over complicate things and is beyond what you're trying to accomplish.