Mitel 5320 Phones not getting DHCP

[Craig222]

Hi,

I am trying to add new phones to our network but they are getting an error - 'Nak/LeaseOver->reset, Resetting phone...'

If I set a static IP address on the phone, the phone works fine, so it seems that DHCP is a problem.
If I set a DHCP reservation, the phone also works fine!?

it is connecting to a Cisco 3650 and the port is configured as follows:-
switchport access vlan 2
switchport mode access
switchport voice vlan 10
spanning-tree portfast

Help!

 

[Craig222]

Hi sarond, it seems like this phone is hitting a different dhcp server that one that works (we have 3 DHCP servers). How do I direct the non working phones to the right server?

 

[Craig222]

Hi sarond,

To answer your previous questions-

I have removed the vlan setting from the scope option-no difference.
The FW versions are exactly the same.
A phone no longer works after static>FW upgrade>dhcp change.

 

[wireman50]

In my ignorance I thought that was what the helper was for? I reckon CDP is interfering for some reason; but just a guess (I don't know Cisco) What address is the correct dhcp server on? Can you set a static route from the vlan10 addresses to the correct DHCP server in the switch's involved TBH I thought that was what the helper did...)? (I am in the outer limits of my knowledge here so please forgive any stupidity)

 

[sarond]

It's odd that existing phones work, normally if something was wrong you would have seen issues previously.

What other DHCP Servers do you have besides the 2012 Server? What VLAN are they in?
What happens if you put the phone in teleworker mode?

 

[Craig222]

DHCP server phones prefer-
interface GigabitEthernet2/0/31
switchport access vlan 2
switchport mode access
channel-group 14 mode active
!

Other DHCP server-
interface GigabitEthernet2/0/36
description Connected_to_vHost4
switchport trunk native vlan 2
switchport trunk allowed vlan 2,998,999
switchport mode trunk

When the phones are in teleworker mode they get the same error - 'Nak/LeaseOver->reset, Resetting phone...'

 

[sarond]

So why 2 DHCP Server on the same VLAN? Is Option 125 with VLAN tag on that server as well?

Can you ping 192.168.10.1 (Switch VLAN10 Address) from the 2012 DHCP Server?

 

[meneerB]

Is option 125 only at dhcp server 172.16.0.63?

Make it easy and remove the other one

interface Vlan10
No ip helper-address 172.16.0.64

Also i dont think ip directed-broadcast is needed.

Because CDP forces the phone to do a dhcp request in vlan 10, option 125 should be removed in vlan 2 (only in 10)

If this does not help, the best way to check what is going on is to use wireshark.
Mirror the interface of the phone to a nearby interface with your laptop.
Type bootp and you should see one or a couple of dhcp discovers
Then an offer of the dhcp server, then a request of the phone and a acknowledge of the server.

http://www.sbarjatiya.com/notes_wiki/index.php/Mirroring_ports_on_Cisco_switches

https://wiki.wireshark.org/DHCP

 

[VinceWhirlwind]

Craig222 (Systems Engineer)(OP)8 Dec 17 08:58
Hi sarond, it seems like this phone is hitting a different dhcp server that one that works (we have 3 DHCP servers). How do I direct the non working phones to the right server?

That would seem to be the problem then, what DHCP server are they going to exactly?? Is it one of these?
ip helper-address 172.16.0.63
ip helper-address 172.16.0.64

(Incidentally, why do you have IP-Helpers for these IP addresses on the VLAN2 interface? There is no point, and the server might even get duplicate requests if you do that).

Or is it another DHCP server that is seeing the broadcast within the Voice VLAN10? Or is the phone not using CDP and broadcasting its request in VLAN2 and seeing another DHCP server on that subnet?

And again, the thing I'd be looking at towards the start of troubleshooting this is what address within which DHCP scope is being reserved by the server when it receives the DHCP request? If it's the wrong scope that's creating the reservation that would tell you what your next step is going to be.

If brand new phones don't have CDP support in their factory-installed firmware, then the bootup sequence for a new phone is going to be:
1/ Bootup in VLAN2, issue DHCP request on VLAN2
2/ All DHCP servers on VLAN2 will see the request and answer it. VLAN2 scope provides IP address + Option125, including Voice VLAN10 in the option
3/ Phone will put its LAN interface as tagged in VLAN10, send a DHCP Release on VLAN2, send a DHCP Request on VLAN10
4/ DHCP scope for VLAN10 will issue an IP address + Option125
5/ Phone is now addressed in VLAN10 and uses Option 125 to find its controller to register and download current firmware.

 

[meneerB]

Vince, maybe he uses pc's in vlan 2 and uses the ip helper for that.

But I think he left his own conversation, and we are only talking to ourselves...

 

[Craig222]

Hi meneerB / VinceWhirlwind,

Sorry I have all but given up on this and just started to accept static addressing was the only way to go!

I have no idea why ip helper-address is being used as the setup is before my time. We do have PCs in VLAN2 so that is maybe why.

Thanks for your help.

 

[meneerB]

okay Craig222,
no worries. Let us know what you did!

 

[VinceWhirlwind]

PCs in VLAN2 do not need IP Helper pointing at servers in the same VLAN2 - those servers, being in the same broadcast segment as the PCs, will see the PC's broadcasted DHCP request - the IP helper does not need to forward the broadcast within the same segment that the broadcast is sent.

 

[kwbMitel]

PC's also do not typically used Tagged traffic so using PC's to test a VOIP environment is not reliable.

**********************************************
What's most important is that you realise ... There is no spoon.

 

[meneerB]

Kwbmitel,
I think he only said that he tested his pc untagged in the voice vlan to test dhcp.

@Craig, what is your plan now on the switches?

 

[Craig222]

Yes meneerB you are correct, I only used the PC as a test to make sure the Mitel scope was giving out addresses, which it did successfully.

I am unsure at the moment where to proceed with this!

 

[wireman50]

I would put option 125 on to both DHCP servers referenced in the helpers and see what happens (just as a test and OOH if you can).

 

[Craig222]

Hi wireman50,

I have put option 125 on both server but that hasn't made a difference, thanks anyway.

 

[meneerB]

 

[meneerB]

Craig222,

I was a bit annoyed by how it could be difficult to setup the scope options

I've posted a FAQ how to set it up.
With this FAQ, you should be able to get your phones working
(in one of the 2 screenprints, I've put your voice vlan 10 as an example: 0xA)

Try the steps in the FAQ step-by-step and let us know if it helps.
faq1329-7925

 

[Craig222]

Hi meneerB,

That link is broken. Can you please re-add the link, I would be very interested in trying out your suggestion.