Using Two Subnets To Change Network Configuration

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Problem: My network uses the 192.168.1.0/24 network. Since is the most common network in all of the world it begins presenting problems when I want to set up vpns, or try to do other routing.

The solution: Change the network from 192.168.1.0/24 to 172.24.24.0/22. This is somewhere in the middle of the less frequently used RFC-1918 20 bit private network range. My network contains 40 or so nodes, windows, linux, and proprietary operating systems of various types (TiVos, iPhones, iPads, TVs, BluRay players, WAP’s, etc.)

What I would like to do to minimize down time would be to create a single new machine on the network with addresses on both networks and set up as a router between the networks.
That way, I can convert the machines one at a time, and not loose any connectivity. When all done, take the temporary router down and just use the new addresses.

Machines are set up both static and DHCP, and there are some virtual servers running on a VMware machine. Updating all of the machines using DHCP can be done in a single pass, but the static machines will have to be done one at a time.

Can anyone give me any pointers to web sites to help set this up. I know how to set up multiple addresses on the same NIC (eth0 and eth0:0). After that, I’m at a bit of a loss.

And Yes, I know setting up multiple subnets on the same physical wire is a bad idea, but this is only for a couple of days until I can get everything moved to the new address scheme.

Thanks

Harold

One thought on - Using Two Subnets To Change Network Configuration

  • I can confirm that this works – I’ve done it a few millennia ago. As I
    very vaguely recall you need to turn on forwarding and set up routing on the router machine. Also any routers on the network segment might need to be changed to send traffic destined for the new network to the router. You might have issues with DNS, WINS, etc. You would need to change any routers to not use the temporary router when you switch to the new network. Why? It can be confusing, yes, but many people route VOIP over the same cabling to desk phones.

    Cheers,

    Cliff

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