04-10-2012 11:46 AM - edited 03-16-2019 10:34 AM
Hi,
We are having issue IP-phone 7940 some of them not getting IP address from DHCP server but some Phones are getting without issue.
We verified DHCP helper is configured correctly on Core-Swicthes .
04-10-2012 11:51 AM
Hi Mohan,
Please try performing factory reset once and see.
Hope it helps.
Anand
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04-10-2012 11:59 AM
Hi,
No, We did the same but still it is not getting IP address. guid eme.
Regards,
Mohan
04-10-2012 12:03 PM
did you check the firmware on all the phones. The ones that are not getting it?
04-10-2012 12:23 PM
Hi,
We are using two model phones - 7911 & 7940. We have two voice vlan 38 & 39. Currently those IP-Phones are connected to vlan 38 and user moved to different location and those phones are connecetd to new voice vlan 39 but it is not getting Ip address from DHCP.
Firmware - 7911- SCCP11.8-3-4sr1s & 7940 - P00308000800.
Regards,
Mohan
04-10-2012 12:52 PM
DHCP problem is hardly a problem related to the phone itself. If you configure an IP Address manually does the phone registers?
If you want to troubleshoot the DHCP allocation problem we would need a packet capture taken with a span session from the back of the phone https://supportforums.cisco.com/docs/DOC-11599
04-10-2012 02:52 PM
Thanks, I will capture and update.
I am new to VOIP environment and current setup has CCUM-6.1.0 Version , Cluster SUB, PUB,ICM,IEM. Could you provide basic document configuration and setup documents.
04-10-2012 09:32 PM
Hi,
What is the configuratoin you have done in interface VLAN for the new VLAN 39. And is IP helper address command used if DHCP server not on same network and is DHCP server reachable from the VLAN 39.
Regards
Ronak patel
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04-10-2012 07:46 PM
Hi Mohan.
Are you using voice vlan in your environment?
Is that port in Data VLAN & Voice Vlan?
04-11-2012 12:56 AM
What Robert is saying is correct. DHCP is far from being related to the phone, but could be in some defective firmwares.
try to plug your phone in a switch port where another phone is communicating with no problem with your DHCP server.
If it registers, double check the configuration on that port and apply it on all other ports.
Optionally, you can try a hard-reset and test again.
04-11-2012 09:46 AM
Yes. We tested Switch level. Same results but we did the packet capture we notice that Phone is sending DHCP discovery request but not getting DHCP (Windows Server) respond from server.
Configuration on Switch side Same as other Voice Vlan and Access port configured correctly.
Packet capture Source -0.0.0.0 Designation 255.255.255.255 Protocol- DHCP length - 368 Info- DHCP discover - Transaction ID 0X14703F1.
04-11-2012 10:08 AM
Please add the full .cap file so we can review. In any case if you don’t see any response coming from the server I think the phone will just sit there cycling.
04-11-2012 10:24 AM
Did you faced same kind of problem IP helper is not working correctly on different Vlan-SVI's? Do you have any documents to check IP helper and DHCP are working or not.
DHCP is providing Ip address some of the IP- PHONE but remaining 50% not getting DHCP IP address.
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