Switches, Hubs, and Modems
Showing results for 
Search instead for 
Did you mean: 

ip address planning guide

Go to solution
Davide Depaoli_3
Valued Contributor

ip address planning guide

I'm working on a project for a customer that needs to migrate his lan (campus style lan, with some buildings) from one ip address class to another.
Is there any planning guide or docs with checklist to follow to make a good job ?

thanks in advance
kind regards
Ron Kinner
Honored Contributor

Re: ip address planning guide

Don't know of anything canned other than

http://www.cisco.com/univercd/cc/td/doc/cisintwk/idg4/nd2002.htm or the CCDA training manual.

The major steps are:

Site Survey: What do you have now, where is it, if static what is its IP address and what operating system does it use, who controls it, how do we contact them, do they know how to change the IP.

Design and Document New Network: What range will we need, is it big enough for growth, should we break it up into smaller subnets, what static IPs will be needed and who get them. Do we need more routers, switches, NICs, cables etc.

Prepare: Notify customers of date of change and their responsibility, Provide step by step instructions for changing IP data or switching to DHCP for all known types of operatings system, Assign new static IPs where required. Shorten lease time on DHCP (verify that you have admin passwords for DNS and know how to do to change the address pool). Add secondary addresses to routers or secondary NICs to server or consider NAT. Freeze changes after a certain date until after changeover. Publish number to call if it doesn't work. Order any required equipment.

Changeover. Reconfigure DNS servers, reconfigure static IPs on servers, have DHCP users reboot or release and renew. Test connections to major servers.

Cleanup. Fix the 10% who didn't get the word.

I assume you are talking about moving from something like 192.168.x.0 to or Is this all one big flat network or are you breaking it up into many smaller subnets?

A lot depends on the original setup. Are you using DHCP? If so, are there some servers and printers which have static addresses? You will need to locate all of these ahead of time and make sure that the administrator a. Still has the admin password and b. Knows the new address, mask, gateway, DNS, WNS and c. Knows how to change them and d. Knows when. Then you will need to get the word out to everyone using DHCP that they will need to reboot their system after the changeover. If a microsoft network do you have SMS so you can do things remotely?

If you are using static then you have to find every one of them and get its owner to change the setup. There will always be a few you don't find or who are on vacation.

One way to ease the transistion if you have Cisco routers (and possibly others) is to assign a secondary addresses in the new subnet and perhaps also use NAT or a second interface to make your major servers respond to both the old and new addresses for a change. With DHCP you can shorten the lease period in the weeks before changeover so that the machines will try to renew on their own even if the owner isn't around.


Davide Depaoli_3
Valued Contributor

Re: ip address planning guide

Thank you very much Ron for your explanation.
regards Davide
Davide Depaoli_3
Valued Contributor

Re: ip address planning guide

Thread closed