Ip phone cannot get DHCP ip adress from CUCM

[nicanor00]

Hi

I have CUCM 12 and ip phone 7821

CUCM, IP phone and ISR Router with Vlan sub interface are  connected on the same 9200 poe switch

CUCM IP adress 192.168.10.2/24

CUCM gateway 192.168.10.254

DHCP pool in CUCM 192.168.10.100 to 192.168.10.200

VLAN 12 is data vlan on my network (192.168.12.0/24)

VLAN 10 is voice vlan on my network (192.168.10.0/24)

see below the configuration of the different interface of switch and ISR router

ISR Router  interface configuration

interface GigabitEthernet0/0/0.1
description ISR router sub interface Connected to VOICE NETWORK int G1/0/1 of the switch
encapsulation dot1Q 10
ip address 192.168.10.254 255.255.255.0

Switch 9200 poe interface configuration

interface GigabitEthernet1/0/1
description c9200 switch port connected to the ISR Router
switchport mode trunk

interface GigabitEthernet1/0/2
description c9200 switch port connected to the CUCM
switchport access vlan 10
switchport mode access

interface GigabitEthernet1/0/3
description c9200 switch port connected to the IP PHONE
switchport access vlan 12
switchport mode access
switchport voice vlan 10

Please what should I change in my configuration ? please help

[balaji.bandi]

You need an ip-helper address here i guess.

ip helper-address x.x.x.x

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dhcp/configuration/xe-16-7/dhcp-xe-16-7-book/dhcp-relay-agent-xe.html

[nicanor00]

where should I configure this command ip-helper

[collinks2]

---

if you want to use ip -helper address,you configure it on the ISR to help the phones get dhcp address from the cucm dhcp service.

I advise you set up dhcp pool in your router and deactivate dhcp service on the cucm

[balaji.bandi]

here is the config :

config t
!
interface GigabitEthernet0/0/0.1
ip helper-address  192.168.10.2
!
end

test, if that works write the config.

[collinks2]

I strongly advise you set up dhcp pool in the ISR. Deactivate DHCP service in the CUCM.Your voice vlan is on the router and there is no dhcp pool for that voice vlan network.

[Nithin Eluvathingal]

Configure the below Under your interface.

interface GigabitEthernet0/0/0.1

ip helper-address 192.168.10.2

Make Sure that you have done all  Required DHCP  configurations ON CUCM and Services running on CUCM.

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/10_0_1/ccmcfg/CUCM_BK_C95ABA82_00_admin-guide-100/CUCM_BK_C95ABA82_00_admin-guide-100_chapter_01010.html

[nicanor00]

Hi

I configured but it still not work

interface GigabitEthernet0/0/0.10
ip helper-address  192.168.10.2

[collinks2]

what's your reason for not implementing dhcp service in your router?

[Nithin Eluvathingal]

Could you please share  the CUCM dhcp configuration screenshot.

[Roger Kallberg]

The primary advice would be to stop using CM for DHCP service as it’s notoriously unreliable. If you search the forum you’ll find numerous posts on this topic. Basically anything else is preferable, setup in IOS on a switch/router or use another server, Windows or any other preferred OS, to provide the DHCP service.

[collinks2]

Thanks Roger for that elaborate explanation

[Roger Kallberg]

Your very welcome.