IP Phones getting IP address outside of scope.

Posted on 2006-07-03
Last Modified: 2010-08-05

We have 65 Shoretel IP Phones and they are all pulling addresses outside of DHCP scope which means they do not update the CFG files automatically and the date and time is incorrect.  We have our scope setup from 16.0 to 20.255 and exclude 16.0 to 16.255 for network appliances, 17.0 to 17.255 for servers, and 20.0 to 20.255 because we aren't using this range.  We are using 18.0 - 19.255 for computers, phones, and printers.

The problem is everytime we clear the IP address from the IP Phones they continually get a 20.x address which is in our exclusions range which means they do not get a proper lease and there for will not update the date and time correctly.

We have rebooted the domain controller (DHCP Server), shoretel server, phone switches, and the phones themselves.  We have contacted our vendor and they can't figure out if the problem lies within the network or the phone system.

I'm hoping one of you fine experts out there might be smart enough to atleast point us in the right direction.

Thank you in Advance
Question by:jaeIT
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LVL 10

Expert Comment

ID: 17031981
Is each phone always getting the same 20.x address or are they different 20.x address (i.e. phone1 always gets 20.1, phone2 always gets 20.2, etc)? It could be an internal IP cache if it's timing out from receiving a response from DHCP (just thinking off the top of my head -- never used Shoretel IP phones)..

Author Comment

ID: 17032057
Each phone will grab the smae IP address unless you clear everything on rebooting the phone is which case it will go up a couple numbers... example

this morning my phone had 19.219  when rebooted and cleared it grabbed 20.29 rebooted and cleared again it got 20.31  after a couple more times I'm up to 20.43....

We have plenty of 18.x and 19.x address that are not being used  in DHCP we just can't figure out why these phones will not grab one of those.

Also I should mention that right before this happened a fellow co-worker accidentally turned off 2 of our 4 switches and then turned them back on... that was on a friday 2 weeks ago.  the next monday we can in and all but like 3 phones had the wrong date and time.

LVL 10

Expert Comment

ID: 17032106
Have you tried setting IP reservations on your DHCP server for each of the phones? How are you doing the exclusions?
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Author Comment

ID: 17032169
I'm no DHCP expert by any means so what exactly is a reservation?  Would that mean would have to statically set each IP address for the phones?  

We have one main scope which is X.X.16.0 to X.X.20.255.
Excluded range X.X.16.0 to X.X.16.255  --> For network appliances ie. Cisco's, Netscreens, Switch's
Excluded range X.X.17.0 to X.X.17.255  --> For Servers
Excluded range X.X.20.0 to X.X.20.255  --> We don't need them yet.

No reservations setup at all.  Also let me add that we have had these IP phones for over a year with no problem and have made no changes to our scope until recently when the phones started getting X.X.20.X addresses we added the 20.X eclusion, but the phones still get the 20.X addresses.

Is this making any sense?

LVL 10

Accepted Solution

victornegri earned 250 total points
ID: 17032558
On your DHCP server (I'm assuming Windows): Right-click reservations and add a new reservation. You will have to enter the MAC address of the phone and the IP you would like assigned to it. That's it. When the phone goes looking for a new IP, it "should" receive the IP from the reservation.

Another thought... in the DHCP console, does it show that the 20.x IPs were handed out to the phones? If so, you may need to recreate the exclusion.

Author Comment

ID: 17032817
Thanks for all your help.  We have actually just figured out the problem (well our vendor did actually).  He noticed that one of our generic jetDirect boxes was actually either giving out DHCP address or conflicting with the DHCP server.  Once we unplugged that and rebooted the phones a few times they got valid perfect addresses.

Thank you again for all your help and seeing as how you were the only responding to my question you can have all 250 points.

LVL 10

Expert Comment

ID: 17032990
Thanks. I was wondering whether you had a rogue DHCP server on the network or not (which was why I asked the last question on my previous post)

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