Subnetting

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Ok. Brain picking time...
As an experiment I have 4 Class C networks and need the 3rd to have access to the 1st...

 

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Reading the question literaly - you need a router to connect #1 and #3.

I am assuming these 'class C' networks are either classified under the classfull rules, or /24 under CIDR. Also assuming the network addresses are all different from one another!

Harry.

 

Sorry if you've seen this before, Boyce, but have a look at LearnToSubnet - great resource

 

Harry- thanks, yes i thought it might come to that.

Gav- yes, thanks it is a cracker

 

I should add that if this is a real set of networks, rather than a paper excercise, then you don't need to rush out and buy a router - Linux/other Unixes can be used as a router fairly easily, and some versions of Windows can be coaxed into doing it.

With Windows there is the special case of ICS - this can sometimes be coaxed into doing what you want.

Harry.

 

oh, great thanks harry. Will look into the real life scenario.

 

Can't this also be achieved by having dual NICs (or dual IPs on the one NIC) that allow the two networks in question to communicate ? Seem to remember I had a setup like this before at my last place.

 

This is how it is achieved normaly. However, you need more than just the physical interfaces, you need routing software.

My comment on Linux and Windows was in fact referring to the routing software bit!

Harry.

 

Yeah, I guess. Am I wrong in recalling that it is as simplistic as having network1 use network2 as it's default gateway ? I really should have paid more attention to that setup.

 

It depends on the routing software, but usualy you write a full line in the routing table showing the destination network address and mask and the gateway required to get to it. The TCP/IP stack software *may* do the rest. Whether it does or not is down to whether it is able to route at all. For example I seem to remember there was a early version of Win9x that by default wouldn't route, but the addition of a Registry hack made it do so.

'route print' on a Windows box shows such a table, but note that on many PCs with a PPP interface the entries on a line can be confusing, as M$ keeps changing it's mind on how to show it.

Harry.

 

Further info - this page and pages linked to it seems to be fairly comprehensive on getting Windows to route:
http://www.windowsnetworking.com/articles_tutorials/w2kprout.html

Harry.

 

Cracking link, Harry. That's what I was thinking about. Should help our Boyce solve his problem now.

 

Also Windows 2000 server family and above can route easily if the RRAS (routing and remote access service) is set up. No reg hacks necessary.

You need two NICS of course, one connected to each subnet.

 

Thanks Harry, a great link