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New Member

Cisco Ip phone problem over switch trunk

We have cisco cat 3750 with Ip phones configured on some ports as below..frequently these phones 76x do not acquire addresses or do not work...(ip helper address configured on SVI)..could anyone guide as to how to go about troubleshooting what could be causing this ..it often solves by resetting the native VLAN( we cannot use aux vlan config in this environ just yet)

switchport access vlan xxx

switchport trunk encapsulation dot1q

switchport trunk native vlan xxx

switchport trunk allowed vlan yyy,xxx

switchport mode trunk

speed 100

duplex full

Pointers appreciated

6 REPLIES
Gold

Re: Cisco Ip phone problem over switch trunk

Can you confirm that you have configured VLAN, Speed and Duplex on the phone ??

Hall of Fame Super Red

Re: Cisco Ip phone problem over switch trunk

Hi Mahesh and Mahesh :)

I don't see;

switchport voice vlan YYY

Rob

Hall of Fame Super Red

Re: Cisco Ip phone problem over switch trunk

Hi Mahesh and Mahesh :)

Sorry for second post

Rob

Gold

Re: Cisco Ip phone problem over switch trunk

Rob, to answer this Mahesh, the reason it is not mentioned is coz the Post states:

( we cannot use aux vlan config in this environ just yet)

So, with the aux/voice vlan not being an option, we need to do a Manual config :-)

New Member

Re: Cisco Ip phone problem over switch trunk

Yes the same have been configured ...just would like to know how to go about troubleshooting the same as everytime it starts working after resetting the native VLAn to some oher VLAN and then back to old native VLAn and Lo it starts working

And yes we cannot use voice Vlan in this etup as yet

Thanks and regards

New Member

Re: Cisco Ip phone problem over switch trunk

Hi,

For troubleshooting, you can try configuring Voice VLAN as a access VLAN and see whether Phones are taking the IP address, with the above configuration give static IP.

Karuna

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