12-05-2006, 10:49 PM

Can anybody help me with forcing my system to change the Dynamic IP address assigned under DHCP?

I have a cable modem which uses dynamic IP addresses through Comast. I've been told to change the IP address I should "Renew DHCP Lease" which would possibly change the IP address. But Comast hasn't been very helpful as to the exact procedure for doing this.

I am running a network through an Airport and have a Powerbook and G5 on the network.

Can somebody give me the steps to accomplish this?

12-05-2006, 11:22 PM

I believe all you do is turn you modem off for a short period of time.

12-06-2006, 12:39 PM

Originally Posted by rman

I believe all you do is turn you modem off for a short period of time.

Well I tried that -- sort of. I forgot to shut down my laptop so maybe that is why it didnt work.

But, what would be the sequence to assure this would work?

1) Shut down laptop
2) Renew DHVP Lease
3) Shut down computer (G5)
4) Recycle modem and Airport (unplug both)
5) Plug modem/airport back in after say 5 minutes
6) Reboot computer

You think that is what and how it should be done?

Thanks.

12-06-2006, 01:44 PM

Okay here is the situation you have. Your cable modem is assign an ip address, when it is turn on. At which point your AirPort router picks up this address and uses it. Your AirPort router is using DHCP to assign ip addresses to each of your computers on your network.

Turning the cable modem off and back on does renew the DHCP Lease on the cable modem, but on the Airport router you are still using the same series of ip addresses.

Why do you need to change the ip addresses?

12-06-2006, 01:49 PM

Originally Posted by rman

Okay here is the situation you have. Your cable modem is assign an ip address, when it is turn on. At which point your AirPort router picks up this address and uses it. Your AirPort router is using DHCP to assign ip addresses to each of your computers on your network.

Turning the cable modem off and back on does renew the DHCP Lease on the cable modem, but on the Airport router you are still using the same series of ip addresses.

So are you saying I have to "reset" the Airport at some point in the process? I mean there is a way to do this but I just can't get a handle on how.

Originally Posted by rman

Why do you need to change the ip addresses?

Because I want to.

Not trying to be a smart --- just sayin'.

12-06-2006, 02:02 PM

Your external IP is assigned by your ISP. To get a new external IP you disconnect your modem from the power supply as well as the cable (if its cable) wait several minutes plug it back in and most times you have a new IP...notice the two words "most times". Good luck

12-06-2006, 02:31 PM

Originally Posted by CrossBones

So are you saying I have to "reset" the Airport at some point in the process? I mean there is a way to do this but I just can't get a handle on how.

Because I want to.

Not trying to be a smart --- just sayin'.

The reason, why I asked is you are only going to reset the ip address on the cable modem only. Your ISP (cable company) only has a set amount of ip addresses, which they cycle through each time a cable modem is reset. As was stated before, you may receive the same ip address after your reset your modem. As for your AirPort router you will have make a change to your configuration to get a different ip address.

12-06-2006, 04:30 PM

Thanks guys. I'll give it another shot!

12-11-2006, 07:24 PM

**** I cannot get this thing to change my IP.

I unhooked the cable from the modem. Unpluged the modem and unplugged the AirPort. Shut down all the computers on the network and left everything off for about 1/2 hour.

Reconnected the modem, plugged it in...waited for it to recycle, plugged in the airport and restarted computer...same IP. :mad:

WTF?

12-11-2006, 07:51 PM

The problem is which ip address are you loking at? You will not get a new ip address from your Airport if you have only one item connected to it. Your cable modem may have changed, but you will need to look at your airport configuration

12-11-2006, 09:30 PM

Originally Posted by rman

The problem is which ip address are you loking at? You will not get a new ip address from your Airport if you have only one item connected to it. Your cable modem may have changed, but you will need to look at your airport configuration

Not sure what you mean.

When I check to see my IP address it's the same as it has been for a long time even though I went through the disconnect procedure etc.

The Airport is giving an IP of 10.0.1.3 etc....nothing to do with the actual IP coming from the ISP...right?

12-11-2006, 10:02 PM

There are two ip address in your environment. The one on the cable modem and the other is on the AirPort. The AirPort will give you the same address each time you reset it unless you change it. The cable modem will change from time to time.

12-11-2006, 11:11 PM

Originally Posted by rman

There are two ip address in your environment. The one on the cable modem and the other is on the AirPort. The AirPort will give you the same address each time you reset it unless you change it. The cable modem will change from time to time.

OK, I have no idea how to change the IP address on the AirPort. Apparently that is the problem?

12-12-2006, 11:40 PM

Look at the AirPort users manual, you should find the information you want. I believe you can make the changes using the AirPort Admin utility.