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Expanding TCP/IP subnet...

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philg | 13:48 Fri 01st Aug 2008 | Computers
10 Answers
Just when I though I understood TCP/IP, it seems that I don't :(

I currently have a home network that runs from 192.168.0.1 to 192.168.0.254 with a subnet mask of 255.255.255.0

I now need to extend my local address range up into the 192.168.1 subnet

In other words, my local IP address range needs to be 192.168.0.1 through to 192.168.1.254

I thought I could do that by changing the subnet mask of my router/DHCP server to 255.255.254.0

But it seems no

When I do that (I have a Netgear DG834G)

I change the subnet mask to 255.255.254.0 and the end IP address to 192.168.1.254 (but keep the start as 192.168.0.1) - the router pops up a mesage saying "Warning DHCP subnet has been changed"

BUT it resets my end IP address to 192.168.0.254 and nothing I can do will make it accept 192.168.1.254

What am I doing wrong??

Thanks

Phil G
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Have you tried changing the subnet to 255.255.0.0 ?
Question Author
I have now - same "error"

I'm starting to wonder whether the DG834G even supports this "clever" stuff :(
I think you may be right. Any support number with your router?
Meant to say that these home routers probably assume you don't need more than 250+ connections and so don't cater for it. Best bet is to give the support (if any) a quick call.
Question Author
Yeah - I've done that

Actually, I don't need that many addresses BUT

I have a PVR that's a pain to change ip address of that I'd like to keep at 192.168.0.222

Now my employers have rolled out split VPN tunelling which allows me to see my home net whilst I am tunnelled into the work LAN - PROVIDED I am looking for 192.168.1.xxx addresses :(
We force our VPN users to connect direct to us and they can't use their own network when connected. If they want to surf the net, they do it through the remote server. That way we can also see what they are looking at (hehe!)

It was a bit of a pain to set up initially because we needed to load all sorts of printer drivers on the remote servers depending on what they have at home.
Why not just change the DHCP range to be from 192.168.1.1 to 19.168.1.254?

Question Author
Hi squarebear

I think that's why our lot have introduced "Inverse Split Tunnelling"

Snag is, I've just read that my network has to have 192.168.1.1 as the gateway address so looks like I will have to change the whole subnet

Not what I wanted to do, but such is life

Thanks for your input
Seems to be a misconception here
(except by fo3)

there are 3 classes of subnet
a (huge), b (big) &c (253 available addresses - c is what you have here)
a subnet is a binary number of individual segment taken from the subnet - so when you split a subnet ... you are splitting the range into a number of smaller individual parts - not increasing the number of addresses.
1, 2, 4, 8, 16 subnets - so you get all, half, quarter, eighth of your 256 (-2) addresses

you could try bridging the two nets - (but you would have to have two network cards!

or do as fo3 says and change the range ....
(is it a tivo? http://www.silicondust.com/forum/viewtopic.php ?t=340
Question Author
Yes, it's a Tivo

I think I am beginning to grasp subnets

I didn't appreciate that there were rigidly defined sizes - I thought it was the subnet mask that defined the subnet size

Hence my misconception of dropping one bit from the subnet mask to give me one more bit for addresses in the subnet

Phil G

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