class c to class b questions.???????

[flip31]

Our organization has outgrown our class C IP addressing scheme. We plan to change to a class B address range, to accommodate all of our computers. Currently we have 5 buildings – fiber ran between them – 3com switches in all buildings and Ethernet throughout from there to the desktops. Our internet connection comes from a local ISP where we have a cable modem and an old cisco router which gives us our connection to the outside world. Our network is setup as DHCP to give our machines their IP addresses. Both DHCP servers are running Windows NT 4.0. We are looking to try and change over our IP addressing with a minimal amount of downtime. Is there a way to use two different IP classes at the same time, while we go building to building changing the IP’s of the printers, servers, and other devices??? Any help would be greatly appreciated.

 

[airbourne]

It is all about routing. Check with someone who knows how to program your switches. Essentially a router needs to know where to send a packet. I cannot be complete as I am lacking in my network expertise for my answer, so I hope to start you out by giving you places to look:

Always start with a drawing of your network. My company doesn't have any of these for our network but we are working on it. Obviously keep these drawings out of the wrong hands, but they will cut a majority of your time if you have this.

As to your question - yes, you can use any number of IP classes or subnets. You have to program your routers & switches to properly route the packets, so if one building is a B-class and the other is a C-class, you routers will know how to go between. As for the how - find someone that is certified on your router hardware, or who has done work like this.

Will you have zero downtime or low downtime? That depends on your understanding, documentation, & current network structure. Depending on the skills of your staff, you may have to hire a company who specializes in this type of change-over.

 

[flip31]

I appreciate you help.

 

[Andyleates]

If all your machines are currently on the same subnet and you just want to change class of IP, or create a new subnet, I would think the easiest thing to do would be to change your DHCP server scope to advertise IP addresses of the new subnet, then do a release and renew on each machine, or just reboot them.

You should only have to manually change servers, printers, routers etc that may have a static IP address.

However, as the previous post mentioned, if you do not fully understand how your network hangs together, making a change like this unaided may be unwise.

Andy



Andy Leates MCSE CCNA MCP+I