[cisco-voip] UCM7 won't ACK DHCP Request for remote site phones *

[Maybelyn Plecic]

Hi Mark,

I ran into this issue in the past.  I would say at least determine who the
DHCP servers are.  Do you have the router set to receive DHCP requests?  As
Ahmed mentioned try to trace back where the dhcp relay agent resides if
there are any others of if it is misconfigured? Also do you have a MS DHCP
server also setup to provide IPs to the devices.  Check your switchports to
make sure they are indeed in the correct VLAN. (Access versus Voice VLAN)

The issue I ran to is that, we had two DHCP sources.  I had configured my
Voice Gateways to provide DHCP IP addresses and the client neglected to
mention that he also had a MS Server also providing DHCP IP addresses.
Since we were upgrading and had 2 CUCM servers with different IP addresses,
the phones were still registering with the old CUCM server (4.x) instead of
my new CUCM servers (7.x).

HTH

Maybelyn H. Plecic



2009/12/3 Ahmed Elnagar <ahmed_elnagar at hotmail.com>

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> Try to isolate the problem; run DHCP service on any server you have in the
> main location " on a sperate temp vlan of course in order not to conflict
> with UCM" and try to make the phone acquire thier IP address from it "change
> helper address", if so then it is a problem in the UCM or the VLan/IP range
> that the UCM reside in, other than that then it is a probelm in the DHCP
> relay configuration maybe!!!
>
>
>
> > From: mh at markholloway.com
> > Date: Wed, 2 Dec 2009 16:50:16 -0700
> > To: wsisk at cisco.com
> > CC: cisco-voip at puck.nether.net
> > Subject: Re: [cisco-voip] UCM7 won't ACK DHCP Request for remote site
> phones
> >
> > The router at the remote site is using an ip helper-address. The help
> address is the IP of the DHCP Server (UCM7 PUB) at the main location.
> tshark/wireshark at the main location confirms the DHCP packets are in fact
> arriving at the main location as the phone boots. Looking at wireshark for a
> phone that boot! s at the main location, the DHCP Discover and Request looks
> the same only UCM ACK's the DHCP requests and provides an all the
> appropriate IP information. Considering I can take phones from the remote
> site and power them up at the main site with no problems but then they fail
> again at the remote site is very strange. Erasing the phone config on the
> phone or doing a factory reset doesn't help. I'm lost.
> >
> >
> > On Dec 2, 2009, at 4:40 PM, Wes Sisk wrote:
> >
> > > The remote phones would likely have a 'relay agent' set that helps to
> identify what IP range should be used to issue the address. Is the
> relay-agent field coming through? Is there an appropriate DHCP scope defined
> that covers the IP of the relay agent?
> > >
> > > /wes
> > >
> > > On Wednesday, December 02, 2009 6:29:55 PM, Mark Holloway <
> mh at markholloway.com> wrote:
> > >> UCM 7.1.3 is configured as DHCP server providing addresses for m!
> ultiple subnets both locally and at remote branch offices. 7965 phones on
> same site as UCM acquire DHCP on the voice vlan just fine and register with
> UCM. Phones at remote sites are not acquiring DHCP. I ran a tshark packet
> capture on UCM VLAN and I see the DHCP requests from the phones at the
> branch sites arriving at the UCM site as expected. Remote phones are sending
> DHCP Discover and DHCP Request but its as if UCM ignores the DHCP Request. I
> can take the phone from one of the remote sites and physically plug into the
> voice vlan at the same site as UCM and it works fine.
> > >> Has anyone seen this behavior?
> > >> Regards,
> > >> Mark
> > >>
> > >> _______________________________________________
> > >> cisco-voip mailing list
> > >> cisco-voip at puck.nether.net
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> > >>
> > >
> >
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