Trunk Ports

[sgalarza]

I am trying to clean up old configs on some equipment that I recently became in charge of.  I'm a little puzzled because our access switches were set up as trunk ports, with PC's and IP phones connected to them, they are responding as if they were access ports.  So my question is if an access switch's ports are configured as trunk ports can they be negotiated to become access ports because PC's are plugged into them?  Also the non-negotiate command has not been applied to any interface.

Thanks

[Julio E. Moisa]

Hi

That is not an usual configuration, I have seen switchports connected as trunks to servers like blades but not for end users. 

For end users it should not be a good practice.

[sgalarza]

Right, I was just curious because our PC's and phones function normally despite being plugged into a trunk port.  Thanks for the input Julio.

[Julio E. Moisa]

It was a pleasure,

Please check this link, it can be useful.

https://supportforums.cisco.com/discussion/11142401/trunk-port-question

:-)

[Joseph W. Doherty]

Phone can often be configured to operate on a different VLAN, and so it can use VLAN tags.

Such a port would need be configured as a trunk port, with a native VLAN (if other than VLAN 1) for non-tagged frames (i.e. to/from a PC).

Or, on newer switches, you define the ports as access with a voice VLAN. The latter is also a trunk port, but it's restricted to just two VLANs.  One tagged (for voice usage), the other untagged for other than voice.

[sgalarza]

Thanks Joseph, most of this I already know, it just one of those curiosity questions.

[Joseph W. Doherty]

Ok, then to answer your original question, the switches could be trunked to support dual VLANs on the edge, for voice and data, and they might be configured with trunks if they didn't support the newer voice vlan command or they were configured by an old-timer who did it the old way rather than the new way.

[sgalarza]

Haha, yea that might have been the case, I have updated my ports to be access ports for out data vlan as well as adding the voice vlan command.  Thanks again for the insight.