Author Topic: DHCP shows Bad_Address for some Mitel phones  (Read 2701 times)

Offline mlouie

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DHCP shows Bad_Address for some Mitel phones
« on: September 24, 2018, 08:54:50 PM »
Our Mitel phones get a DHCP address from DHCP on our Windows Server 2012R2 domain controller. We have a problem where dozens of the Mitel phones (though less than half of them) are showing an entry in DHCP of "Bad_Address". We have DNS scavenging enabled, DHCP conflict detection attempts are set to "2" and I cannot find any rogue DHCP servers on the network. I cannot figure out what is causing these Bad_Address entries and why it is only the Mitel phones that this happens to (not any of the PCs). Does anyone have any ideas as to what I can investigate? I have spent many hours googling this and found nothing that solves it. We initially thought this was caused by setting up a failover DHCP server last May but we took that down last May and this problem still persists many months later. We shortened the lease durations on the scopes where this happens from 8 days to 2 days and 3 days (we did that months ago) and that didn't help. We are not aware of any conflicts on our network causing the phones or PCs to have issues (so there are no symptoms of IP conflicts) except that in the last few weeks, a few of the phones will sometimes have no audio when making/receiving calls but that only persists for a few minutes. When that happened this afternoon to a phone, I looked it up in DHCP and saw that it had one of the Bad_Address entries.


Offline Sube100

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Re: DHCP shows Bad_Address for some Mitel phones
« Reply #1 on: September 25, 2018, 01:27:01 AM »
The PBX definitely isn't giving out DHCP as well?

Offline ZuluAlpha

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Re: DHCP shows Bad_Address for some Mitel phones
« Reply #2 on: September 25, 2018, 09:04:54 AM »
Is there anything in common with the ones getting bad addresses? Like coming from the same switch or hosted on the same node?

Offline mlouie

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Re: DHCP shows Bad_Address for some Mitel phones
« Reply #3 on: September 25, 2018, 12:09:52 PM »
No, the PBX is not giving out DHCP. The phones get their IPs from the DHCP server on the Windows server.

Offline mlouie

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Re: DHCP shows Bad_Address for some Mitel phones
« Reply #4 on: September 25, 2018, 12:10:51 PM »
No, the phones are on multiple switches and multiple subnets. We get the Bad_Address entries in 2 different subnets.

Offline VinceWhirlwind

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Re: DHCP shows Bad_Address for some Mitel phones
« Reply #5 on: September 25, 2018, 07:32:59 PM »
Does your DHCP server have multiple NICs, and/or does it have IPv6 enabled on its NIC(s)?
 
Try pinging a "bad address" from the DHCP server then check its ARP table to see which MAC address it is getting for that IP address. Track that MAC address down on the network and see which device it's coming from.
 
Are these 69xx phones? We've had 1 69xx doing very weird stuff with ARP (which brought a whole network segment down), there might be something suspect going on in the 69xx IP stack.

Offline mlouie

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Re: DHCP shows Bad_Address for some Mitel phones
« Reply #6 on: September 25, 2018, 07:54:43 PM »
The DHCP server is virtual and only has one NIC. IPv6 is not enabled.

If I ping one of the bad addresses from the DHCP server and do arp -a, it does not list that address (the server is on a different subnet from it). If I ping it from my PC (on the same subnet) and do arp -a, it lists that address and the same MAC address as is shown in DHCP. The MAC address is for a Mitel phone. I am not aware of any IP address conflicts on our network (when we have these, usually users start calling us as they have issues.)

No 69xx phones. They are 5330 mostly or a similar model.


 

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