Thursday, February 5, 2009

Win 2k3 Routing...

I wanted to do some simple routing from subnet A to subnet B. For some reason I got real confused to why it wasn't working... until I realised I have 'foolishly' missed the obvious and set up the incorrect default gateway on subnet A.

This was because I was setting this subnet up on a network where I already had a default gateway to my router to the internet... let me explain.

I had a gateway router out to the net -
So i had subnet A, then I thought I would use a win2k3 box to practise a bit of RRAS routing. So I set up my Windows Home Server testbox on to IP, and then set up my router box with IPs and
I set up the WinHomeserver as follows:

Subnet mask
Default gateway

(the router box has DNS installed on it - really a caching DNS server, as it forwards all unresolved requests to

I then set the router box IPs as follows



OK, so then I tried to PING ips from the winhomeserver box. After sufficient firewall admendments, I could ping the box itself, and both IPs (202 and 192) on the RRAS box. But I couldnt PING the router....

It was because I was thinking about it all wrong. What i needed here was a NAT box so allow requests from subnet B to subnet a. as soon as i configured the NAT on the RRAS box everything was fine. But why wasnt the LAN only routing working?

It was because i was thinking about it wrong. The RRAS box IPs didnt need default gateways for what i was doing, but what should be set up was this:

Subnet B, have default gateway of (The RRAS box)
Subnet A, ahve the default gateway of (The RRAS box) - this is what i didnt have, as I didnt want the rest of the network to route back to subnet B, but to go out on the net through my main router.

SO, i guess the thrust of this rambling post is that I should have drawn out what i was trying to do before I went setting things up the way I did.

Such fun ;)