SPA 504G Fails to negotiate voice vlan via CDP

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May 14th, 2010
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I can't seem to get the Cisco SPA504G phone to pick up it's voice vlan via CDP with my Cisco 3560 (WS-C3560-24PS) switch.  I am forced to statically define the voice vlan within the phone menu.  I've had this issue with two different phone firmware versions 7.4.3 and now 7.4.4.  I've also had three different software versions on my switch.  Currently my switch is running the latest image 12.2(53)SE2.

I've captured packets and see two-way CDP negotiation but I'm not the CDP expert and can't really tell what's happening.  The switchport configuration looks fine:

interface FastEthernet0/15
switchport trunk encapsulation dot1q
switchport trunk native vlan 101
switchport mode trunk
switchport voice vlan 200
mls qos trust device cisco-phone
spanning-tree portfast

Once the phone boots up after a factory reset (CDP is on) I see the following in the CDP neighbor table.  The IP address it gets is from VLAN 101.

show cdp n d

Device ID: SIP00<snipped>D4
Entry address(es):
  IP address: 192.<snipped>.99
Platform: Cisco IP Phone SPA504G,  Capabilities: Host Phone
Interface: FastEthernet0/15,  Port ID (outgoing port): Port 1
Holdtime : 159 sec
Version :
advertisement version: 2
Duplex: full
Power drawn: 10.000 Watts
Management address(es):

Has anyone else had any issue like this?

Thank You


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David Harper Sat, 05/15/2010 - 17:15
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I don't have a catalyst handy to check this on so I'm going from memory.  But I think you will find that the switchport needs to be configured in access mode.  Your best bet is to make use of the smartports macros for this sort of thing, as they handle the details of the configuration for you.  So use the CLI 'macro apply cisco-phone $access_vlan 101 $voice_vlan 200'.  This will set the port up correctly for you, and should fix this problem.



adam.baird Thu, 05/27/2010 - 17:34
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The Catalyst I have does not support the Macro function that you suggest.  However I was able to get this to work putting the port in access mode.  It is interesting that the Cisco 79x0 negotiate just fine with the port in Trunk mode, but not the SPA5xx.

Thank You

David Harper Sun, 05/30/2010 - 15:48
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I may have the CLI syntax wrong because I don't use the Catalyst switches often these days.  Glad to hear you got it working though.  Interesting that the 7900 worked in trunk mode, as there really shouldn't be a difference between the phones.  If I can get my hands on a Catalyst to test with I'll try and get to the bottom of the problem.




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