DHCP issue with 9608 and 9641 phones

[jones283]

Good morning,

We have a branch office that is using 9608 and 9641 phones. When the office was brought online, we did not have a local file server, so DHCP was being handled via a DHCP server at another location.

Later, we received a file server for this office, and we setup DHCP locally (Windows DHCP). We changed the helper-address on the router from the remote DHCP server to the local file server. As leases started to expire for phones that were going to the remote DHCP server, these phones would not grab an IP locally. Once I added the remote DHCP server as a helper-address, the phones would grab from that remote DHCP server.

Can anyone tell me why a phone would act in this way? Im not located at this branch office, or else I would do some Wireshark traces.

Thanks!

[pprintz]

There is nothing hard coded in the phone settings pointing it to a specific DHCP, right?

Also, did you test resetting a phone after removing the remote DHCP server from the ip helper-address. See if the cleared phone would talk to the local DHCP server?

[jones283]

I had our telco engineer check and the DHCP server is not hard coded into the settings.

Are there specific variables we have to have in our 242 string? These are what we have currently:

MCIPADD
MCPORT
HTTPSRVR


As a test, we added L2Q=1, L2QVLAN, and VLANTEST=60, and that did not make a difference.

Thanks for your help.

[sumit007]

Reset the phones and put the VLAN on which these phones should register. Or you can hard code the Phones to register locally by changing their IP parameters in 46xxsettings file

[oiduran]

Check the 46xxsettings file. There are can be your solution

[fazil3]

When the remote DHCP server works , strange that the local DHCP server doesn't work.

It can be that the phones are not able to reach the local DHCP server. May be in different Vlan or something preventing phones communicating to DHCP server.

Firstly i would suggest to take a wireshark on the local windows dhcp server (when booting a phones), this will say if the phone is sending a dhcp request to this local server. Then troubleshoot accordingly.

[moyaw]

Do you have VLANs in that Branch location?
the phones are SIP or H323?

[yadav29]

put the IP range in the different/dedicated VLAN so that phone can ask for the IP to the DHCP server..
DHCP server works on the DORA process(Discover, Offer, Acknowledge , accept).

[agronw]

Also check if there are two DHCP servers active. In this case things get weired.
Nevertheless your problem description points to the local DHCP server, nothing else. Check, if the DHCP-server is reachable from the phones, if not it seems to be a vlan-issue (wrong vlan etc).
Are you using LLDP?

regards,
andre