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Cisco IP Phones registeration

slaam2013
Level 1
Level 1

I have a strange problem . I have 30 Cisco IP phones when i attached them to a Cisco switch , the IP phones can not able to register. When i replace these Cisco IP phones on other switch , it work fine and register successfully. The configuration are same on both switches .

Switch 3750

Interface range f0/0 -8

switchport mode access

switch access vlan 10

switch voice vlan 20

spanning-tree portfast

I have already did many search with bad results , other thing the switch is POE if anyone asked about the type.

I apperciate your help

2 Accepted Solutions

Accepted Solutions

hi

can you check if some thing which stops your dhcp request?. I hope to check something like IP dhcp snooping. Check with your security team and please check your configuration. i hope to add the below commands to the interface which is connected to your router

interface

ip arp inspection trust

ip dhcp snooping trust

Thank you

please rate if this will help

View solution in original post

10 Replies 10

Ayodeji Okanlawon
VIP Alumni
VIP Alumni

Can the phones contact your DHCP server from this switch? If you plug a pc to one of the ports on the switch, do you  get an IP?

Please rate all useful posts

"opportunity is a haughty goddess who waste no time with those who are unprepared"

Please rate all useful posts

Hi Kamel,

Just to add what Mr. Aok has asked,what is the model and version of both the switches ?

How the switches are connected in setup?

regds,

aman

Hi

answer is no , my cisco IP phones can not contact my dhcp. I think i have a problem to get my IP address.

Thanks

Hi Kamel,

Have u configured DHCP pool on switch?

Do u have enough IP addresses in pool  to be allocated to IP phones?

regds,

aman

hi

can you check if some thing which stops your dhcp request?. I hope to check something like IP dhcp snooping. Check with your security team and please check your configuration. i hope to add the below commands to the interface which is connected to your router

interface

ip arp inspection trust

ip dhcp snooping trust

Thank you

please rate if this will help

Hello

Please clarrify also the dhcp configured on your CUCM , external server or router.

Thank you

please rate if this will help

thanks amanso and kamal , my dhcp server is on my CUCM and all things work fine . I think my problem in my switch , let me Mr/kamal check with security team if security commands are added to my config .

thanks

Hi Kamel,

Check for ACL.along with DHCP port 67 being opened.

regds,

aman

Kamal ,you are true .Our security team found that issue was dhcp snooping . I will apperciate if you give more details about this.

thanks again

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