Voice VLAN traffic through access ports

[bobbyBrown1995]

Normally you would want to trunk this but play along with me here. On a switch I have an access port(g1/0/24) with a data vlan and voice vlan that connects to another layer 3 device. If I decide to configure another port(g1/0/1) on that same switch for a phone and it has the voice vlan, will the voice vlan traffic go out the switch through that access port(1/0/24) ? Voice vlan and data vlan are 2 separate subnets. Thank you!! 

[MHM Cisco World]

connect two SW through access interface with two VLAN one data and other voice, I think this not work. 
the voice vlan work only in access port connect to phone not other SW. 

[Kasun Bandara · Accepted solution]

if you need to send two VLANs in same port, you need to use trunk mode. access ports can have only 1 VLAN. but you can use access port to share Data and Voice VLAN both by configuring Voice VLAN in that port. then access port need to connect to phone and from phone you can connect to PC.

[Joseph W. Doherty]

"if you need to send two VLANs in same port, you need to use trunk mode. access ports can have only 1 VLAN. but you can use access port to share Data and Voice VLAN both by configuring Voice VLAN in that port. then access port need to connect to phone and from phone you can connect to PC."

Sorry, believe (pretty positively) this to be incorrect.  (What's incorrect is the "need to"s.  If you replace those with "should"s and/or "what's usually done"s, then the above statements would be fine.)

As @emurray also notes "The voice VLAN is actually a trunk so you can pass the data VLAN and the voice VLAN in one port."

In his next statement, "Also if it's between switches, the port should be a trunk.", the important word is "should".

However in his next statement, "There is no way you pass two VLANs in an access port ", is a contradiction to his earlier statement, and also incorrect.

Basically an access port with a voice VLAN is a "special/limited" trunk port, which only supports two VLANs.

Before there were voice VLANs, for access ports, you could define a trunk port to act as an edge port, supporting a "data" VLAN (the native VLAN) and a voice VLAN (tagged frames).  (NB: I've actually done this in a production environment; where VoIP phones, with downstream PCs, were connected as expected to an edge port on a switch that did not have the voice VLAN option.)

An access port's voice VLAN doesn't have to be used for voice traffic.  It transmits its "voice" VLAN with tagged frames.

Now if you want to experiment in a lab, connect an access port, with a defined voice VLAN, to another switch using a trunk port, where the access port is the same VLAN as the native VLAN on the trunk port and the voice VLAN is the one and only other VLAN allowed on the trunk port and see if you obtain expected VLAN behavior, like can hosts, in the two VLANs, ping other hosts within the same VLAN on the other switch.  (NB: if CDP is enabled on the ports, it's likely to complain about misconfigured ports.  Switch may also complain about unexpected BPDUs on access port, etc.)

As a quick PT (ver. 8.2.0.0162) example, I configured two 2960-24TT switches, and interconnected f0/1 on both.

Then added:

switch0:

vlan 10
name voice

interface fa0/1
switchport voice vlan10

interface vlan1
ip address 192.168.1.1 255.255.255.0

interface vlan10
ip address 192.168.10.1 255.255.255.0

switch1:

vlan 10
name voice

interface fa0/1
switchport mode trunk

interface vlan1
ip address 192.168.1.2 255.255.255.0

interface vlan10
ip address 192.168.10.2 255.255.255.0

Each switch can ping both of the other switch's SVIs.

BTW, I'm not recommending this for production usage, it's just to clarify what access ports and trunk ports really are, and how you can intermix them.  I.e. how a L2 domain can be extended, with, or without, tagged frames.

[Joseph W. Doherty]

I'm a bit confused exactly how you configure the second port, g1/0/1.

Traffic flows out a port, for the same VLAN, regardless how the port is configured.  I.e. VLAN # traffic behaves the same regardless whether access port # is configured for VLAN #, or access port # is configured with voice VLAN # or trunk port allows VLAN #.

Of course, physically frames for VLAN # will be tagged on access port voice VLANs, as might trunk VLANs, depending on what's the native VLAN for the trunk.

"Voice vlan and data vlan are 2 separate subnets."

Okay, and so?  I.e., again, unclear how that impacts VLAN ports.

[bobbyBrown1995]

Thank you very much for explaining this. Apologies for the bad question, I'm trying to learn these concepts but failing 

[Joseph W. Doherty]

Nothing to apologize for.

If a responder questions your question, just try to clarify what you're trying to find out.

For example, in this case, what's the concept you're having difficulty with?  Perhaps L2 (VLANs) vs. L3 (subnets)?  Or perhaps multiple VLANs on the same physical port?

[emurray]

It is difficult to understand what you really want to accomplish here. The voice VLAN is actually a trunk so you can pass the data VLAN and the voice VLAN in one port. Also if it's between switches, the port should be a trunk.  There is no way you pass two VLANs in an access port