[cisco-voip] DHCP Problems | CME / Windows

Mon Mar 15 16:17:53 EDT 2010

Thanks guys! 

Hyoun Kim
Network Administrator I
Charter Media - East Division
640 Broadmor Blvd, Suite 80
Murfreesboro, TN 37129

Email: Hyoun.Kim at chartercom.com
Office: 615.217.6245
Fax: 615.217.6255

-----Original Message-----
From: Erick B. [mailto:erickbee at gmail.com] 
Sent: Monday, March 15, 2010 2:27 PM
To: Ryan Ratliff
Cc: Kim, Hyoun S; cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] DHCP Problems | CME / Windows

Also. check to see if the data and voice VLANs are cross-connected in
any way. Maybe someone put a cheap switch at their desk or something.

On Mon, Mar 15, 2010 at 1:02 PM, Ryan Ratliff <rratliff at cisco.com> wrote:
> Remember DHCP is broadcast from the client to the server, so it's not the PC
> seeing the DHCP server it's the DHCP server seeing the PC request an
> address.  Because your router has an interface on the data vlan it is going
> to see the broadcast from the PC and the DHCP server on the router will try
> and serve the client an address.
> You may be able to configure ip helper on the router's data vlan to  point
> to the data dhcp server.  While that shouldn't be necessary it may keep the
> DHCP server on the router from doing anything for that vlan.
> You can also try looking at the DHCP database on the router to see if other
> PCs are getting assigned addresses.
> -Ryan
> On Mar 15, 2010, at 11:29 AM, Kim, Hyoun S wrote:
> What's strange is that the DHCP pool I set up for the phones is on a private
> IP range that is unadvertised outside from the CME router.
>
> On the router, I've defined the DHCP pool "phone" with the range of
> 10.10.10.0/24.  There is nothing specified in the ip routes on the CME.  On
> the switches connected to the network, the voice vlan goes to the interface
> on the CME with the IP 10.10.10.1.
>
> I don't see how in the debug log, how the PC even knows about the other DHCP
> server if you can't even ping it or see it.
>
> Hyoun Kim
> Network Administrator I
> Charter Media - East Division
> 640 Broadmor Blvd, Suite 80
> Murfreesboro, TN 37129
>
> Email: Hyoun.Kim at chartercom.com
> Office: 615.217.6245
> Fax: 615.217.6255
>
> From: Ryan Ratliff [mailto:rratliff at cisco.com]
> Sent: Thursday, March 11, 2010 3:17 PM
> To: Chris Ward (chrward)
> Cc: Kim, Hyoun S; cisco-voip at puck.nether.net
> Subject: Re: [cisco-voip] DHCP Problems | CME / Windows
>
> That debug tells me that the dhcp database on the router had a previous
> entry for this client and is now seeing the request on a different vlan.
>
> You can see that after the DHCPNak is sent it sees the request come in,
> confirms it doesn't have a pool for that address range, and doesn't send
> another Nak.
>
> I think you need to see the debugs that result in this client getting into
> the dhcp database to begin with.
>
> -Ryan
>
> On Mar 11, 2010, at 4:03 PM, Chris Ward (chrward) wrote:
>
> "010542: Mar 11 15:35:27.595 EST: DHCPD: client has moved to a new subnet."
>
> That doesn't seem good. Any ip-helpers in use here?
>
> +Chris
>
> From: cisco-voip-bounces at puck.nether.net [mailto:cisco-voip-bounces at puck.nether.net] On
> Behalf Of Kim, Hyoun S
> Sent: Thursday, March 11, 2010 3:41 PM
> To: Ryan Ratliff (rratliff)
> Cc: cisco-voip at puck.nether.net
> Subject: Re: [cisco-voip] DHCP Problems | CME / Windows
>
> I do have another router, but it doesn't point anything to the CME router.
> All I did was configure the CME router to use a valid IP within the subnet.
>
> Here is the output I've gotten so far:
> 010540: Mar 11 15:33:46.498 EST: DHCPD: checking for expired leases.
> 010541: Mar 11 15:35:27.595 EST: DHCPD: DHCPREQUEST received from client
> 0100.247e.1137.4c.
> 010542: Mar 11 15:35:27.595 EST: DHCPD: client has moved to a new subnet.
> 010543: Mar 11 15:35:27.595 EST: DHCPD: Sending notification of ASSIGNMENT
> FAILURE:
> 010544: Mar 11 15:35:27.595 EST:   DHCPD: htype 1 chaddr 0024.7e11.374c
> 010545: Mar 11 15:35:27.595 EST:   DHCPD: remote id 020a0000ac15c8c100000000
> 010546: Mar 11 15:35:27.595 EST:   DHCPD: circuit id 00000000
> 010547: Mar 11 15:35:27.595 EST: DHCPD: Sending notification of
> ASSIGNMENT_FAILURE:
> 010548: Mar 11 15:35:27.599 EST:  DHCPD: due to: Reason with no text
> explanation
> 010549: Mar 11 15:35:27.599 EST:   DHCPD: htype 1 chaddr 0024.7e11.374c
> 010550: Mar 11 15:35:27.599 EST:   DHCPD: remote id 020a0000ac15c8c100000000
> 010551: Mar 11 15:35:27.599 EST:   DHCPD: circuit id 00000000
> 010552: Mar 11 15:35:27.599 EST: DHCPD: Sending DHCPNAK to client
> 0100.247e.1137.4c.
> 010553: Mar 11 15:35:27.599 EST: DHCPD: broadcasting BOOTREPLY to client
> 0024.7e11.374c.
> 010554: Mar 11 15:35:28.623 EST: DHCPD: Sending notification of DISCOVER:
> 010555: Mar 11 15:35:28.623 EST:   DHCPD: htype 1 chaddr 0024.7e11.374c
> 010556: Mar 11 15:35:28.623 EST:   DHCPD: remote id 020a0000ac15c8c100000000
> 010557: Mar 11 15:35:28.623 EST:   DHCPD: circuit id 00000000
> 010558: Mar 11 15:35:28.623 EST: DHCPD: DHCPDISCOVER received from client
> 0100.247e.1137.4c on interface FastEthernet0/0.
> 010559: Mar 11 15:35:28.623 EST: DHCPD: Seeing if there is an internally
> specified pool class:
> 010560: Mar 11 15:35:28.623 EST:   DHCPD: htype 1 chaddr 0024.7e11.374c
> 010561: Mar 11 15:35:28.623 EST:   DHCPD: remote id 020a0000ac15c8c100000000
> 010562: Mar 11 15:35:28.623 EST:   DHCPD: circuit id 00000000
> 010563: Mar 11 15:35:28.623 EST: DHCPD: there is no address pool for
> 172.24.200.193.
> 010564: Mar 11 15:35:28.651 EST: DHCPD: DHCPREQUEST received from client
> 0100.247e.1137.4c.
> 010565: Mar 11 15:35:28.651 EST: DHCPD: no subnet configured for
> 172.24.217.73.
> 010566: Mar 11 15:35:28.651 EST: DHCPD: Finding a relay for client
> 0100.247e.1137.4c on interface FastEthernet0/0.
> 010567: Mar 11 15:35:28.651 EST: DHCPD: Seeing if there is an internally
> specified pool class:
> 010568: Mar 11 15:35:28.651 EST:   DHCPD: htype 1 chaddr 0024.7e11.374c
> 010569: Mar 11 15:35:28.651 EST:   DHCPD: remote id 020a0000ac15c8c100000000
> 010570: Mar 11 15:35:28.651 EST:   DHCPD: circuit id 00000000
> 010571: Mar 11 15:35:28.651 EST: DHCPD: there is no pool for 172.24.200.193.
> 010572: Mar 11 15:35:46.500 EST: DHCPD: checking for expired leases.
>
> That MAC address is a PC.
>
>
> Hyoun Kim
> Network Administrator I
> Charter Media - East Division
> 640 Broadmor Blvd, Suite 80
> Murfreesboro, TN 37129
>
> Email: Hyoun.Kim at chartercom.com
> Office: 615.217.6245
> Fax: 615.217.6255
>
> From: Ryan Ratliff [mailto:rratliff at cisco.com]
> Sent: Thursday, March 11, 2010 11:48 AM
> To: Kim, Hyoun S
> Cc: cisco-voip at puck.nether.net
> Subject: Re: [cisco-voip] DHCP Problems | CME / Windows
>
>
> debug dhcp detail
>
> debug ip dhcp server event
>
> debug ip dhcp packet
>
>
> I don't believe the ios dhcp server will attempt to serve requests on an
> interface it doesn't have a dhcp pool defined for.  Do you happen to have
> another router with a data vlan address and ip-helper pointed to the CME
> router?
>
> -Ryan
>
> On Mar 11, 2010, at 12:21 PM, Kim, Hyoun S wrote:
>
>
>
> After implementing the last Cisco VoIP solution for our offices, I've
> stumbled across a problem with machines (all Windows) that occasionally drop
> their network connection just briefly every couple of hours.  While this
> normally wouldn't be a problem, it is for us because we redirect several of
> the default Windows folders to a Windows server.  When the connection drops,
> Windows loses these folders and you have to log off/log on to get them back.
>
> Looking into the Event Properties of various windows machines, it
> intermittently gets a DHCPNACK message from another DHCP server.
> Unfortunately, that DHCP server is the DHCP pool I set up on the CME.
>
> One of the Ethernet ports on the CME is configured for the data VLAN.  This
> is connected to our switch with only the data VLAN being shown when I
> perform a show spanning-tree on that interface.
> The other Ethernet port is strictly configured for the voice VLAN and
> displays only the voice VLAN in a show spanning-tree on that interface.
>
> Each PC port has both the data VLAN & voice vlan defined in the
> configuration w/ the phone containing "switchport voice vlan 100".
>
> Do you guys have any suggestions on why the Windows machines are trying to
> pull an IP from the Cisco DHCP server I set up for the phones?
>
> Thanks in advance.
>
>
> <image001.jpg>
> ________________________________
> Hyoun Kim * Network Administrator I - East Division
> 640 Broadmor Blvd * Suite 80 * Murfreesboro, TN 37129
> ' 615.217.6245 * ' 859.312.6941 * 7 615.217.6255 * * Hyoun.Kim at chartercom.com
>
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