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Lync/SfB phones not always receiving DHCP when connected to 5130

BadHabit
Advisor

Lync/SfB phones not always receiving DHCP when connected to 5130

Hi guys,

I´m fighting with some Lync phones here, they are powered by PoE on an 5130 but out of 5 times they are booted, the DHCP works maybe once or twice. All the other times the phones stays without IP and needs to be rebooted.

Connecting a PC to the same port works in an instant, also connecting a PC to the integrated switch in the phone works as it should, but the phone itself mostly not.

I tried several port configurations but nothing seems to change the behaviour. Once it is booted and received a DHCP address everything is OK and the phone is working until the next reboot. I can reproduce the problem on several switches using either a HP 4120 phone or a Polycom CX3000. also it makes no difference is the port is configured as hybrid (to put the PC in a different VLAN) or as access, directly in the voice VLAN. Playing with stp edge-port also has no effect (no wonder as STP is anyway disabled globally).

Here´s one example interface configuration:

interface GigabitEthernet2/0/7
port link-type hybrid
port hybrid vlan 56 tagged
port hybrid vlan 8 untagged
port hybrid pvid vlan 8
undo voice-vlan mode auto
voice-vlan 56 enable
undo jumboframe enable
qos trust dscp
poe enable
loopback-detection enable vlan 1 to 4094
loopback-detection action shutdown

 

The switch (3-member IRF) is running R3113P03, wich is of course not the latest version, but in the Release notes of R3115 I do not see any solved problems coming close to this behaviour.

Anybody has an idea?

Thanks in advance

BadHabit

6 REPLIES
parnassus
Honored Contributor

Re: Lync/SfB phones not always receiving DHCP when connected to 5130

Can you provide more details about your Lync/SfB VoIP phones (Brand, Model and Firmware)? ...sometime diagnosing the edge side too can be helpful.

What's about diagnosing the DHCP Server service side (DHCP Server service configuration, DHCP Snooping, etc.)?

Edit: sorry, mistake (it's too earlyn for me today)...I though you had rebooting problems on VoIP phones...instead you have DHCP issues. So what I wrote below is not exactly relevant in this case.

Did you checked the PoE status of IRF Stack member's PSE and the status of powered devices on the switching side (e.g. with the help of display poe pse and display poe device commands)?

I recall there is a Firwmare update about PSE (read about it here and here): was that yet updated on IRF Stack member (or on all IRF Stack members) supplying PoE to your Lync/SfB VoIP terminals?

BadHabit
Advisor

Re: Lync/SfB phones not always receiving DHCP when connected to 5130

Hi,

Model is Polycom CX3000 or HP 4120 with latest Microsoft firmware from september 2016 (but also older firmwares have this issue).

I do not know what I could do on DHCP side there as the configuration is working, but not always. And when I connect a PC to the very same interface I get an IP in an instant...

 

parnassus
Honored Contributor

Re: Lync/SfB phones not always receiving DHCP when connected to 5130

Who is acting as (which system has the role of) DHCP Server for each of your VLANs? Is it - maybe - the IRF Stack itself or is it an external DHCP Server service that your IRF Stack is/should relaying of (for all VLANs involved/required), is DHCP Snooping enabled or disabled, is DHCP Relay properly configured...what's about DHCP Pool, LLDP...and so on.
BadHabit
Advisor

Re: Lync/SfB phones not always receiving DHCP when connected to 5130

Hi,

DHCP is a Windows server, so I configured DHCP relay on this VLAN in the Core. DHCP Snooping is disabled. We´re not using LLDP-MED, but when the phone receives an IP it changes to the Voice VLAN delivered by DHCP as it should...but it only sometimes receives an IP

parnassus
Honored Contributor

Re: Lync/SfB phones not always receiving DHCP when connected to 5130


BadHabit wrote: DHCP is a Windows server, so I configured DHCP relay on this VLAN in the Core. DHCP Snooping is disabled. We´re not using LLDP-MED, but when the phone receives an IP it changes to the Voice VLAN delivered by DHCP as it should...but it only sometimes receives an IP

(1) DHCP is a Windows Server: so you should diagnose that too (what log DHCP service reports?).

(2) ...but it only sometimes receives an IP: that should not happen...it should work always, not sometime (does the DHCP Voice Pool scope has sufficient IP Addresses for your Voice VLAN to manage all your connected IP Phones?).


BadHabit
Advisor

Re: Lync/SfB phones not always receiving DHCP when connected to 5130

Hi again,

already an old issue, but still fighting with the same problems, also after updating switch firmwares etc...nobody else has this?

The phone clearly reaches the DHCP as a lease is created, but somehow the answer doesn´t always reach the phone, as sometimes it works and most of the time it doesn´t.

And as soon as the phone finally received an IP, it works like it should forever...until the next switch reboot where the fight starts again