Wired Intelligent Edge (Campus Switching and Routing)

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Occasional Contributor II

Voice VLAN assignment via LLDP

I have seen numerous posts that refer to this in some form but can't seem to find a straight answer.  In my case I have a 2530 running 16.10.  I know I can add the "voice" command under a VLAN configuration to identify it as a voice vlan as below.

vlan 1
name "DEFAULT_VLAN"
no untagged 19
untagged 1-18,20-24,27-28,Trk1
ip address dhcp-bootp
exit
vlan 100
name "Voice"
tagged 1-18,20-24,27-28,Trk1
no ip address
voice
exit

 

But everything I have read so far basically says that voice command only has to do with QoS.  I have also enabled both CDP and LLDP including MED/TLV.  But what exactly is the configuration that causes LLDP to inform the attached phone that it is supposed to use tagged VLAN 100 for it's traffic.  The documentation that I have says absolutely nothing about this but this is used so commonly in the VoIP world across numerous manufacturer's phones that I'm a bit flabbergasted it isn't more obvious.

 

If it isn't supported on the 2530 please let me know.  Unfortunately I have made a mistake with the 2530 if that is the case.  Then can somebody tell me what models, if any, would support voice VLAN info via LLDP.

 

Thanks!!


Accepted Solutions
Highlighted
Occasional Contributor II

Re: Voice VLAN assignment via LLDP

I'm going to answer my own question since we just deployed them in production at a customer site.

Yes it works.  It is still a bit unclear what combination of factors makes it work but it basically should boil down to 3 things.

 

LLDP should be enabled.  We actually added...

lldp top-change-notify 1-28
lldp enable-notification 1-28

but I doubt those are necessary to make this work.

 

The vlan configuration should include the voice parameter as shown below.

vlan 100
  name "Voice"
  voice
  exit

 

The vlan configuration should list the ports with phones as being tagged.  This may include ports like those connecting another switch or router as well but for the ports with phones you would normally only have the data vlan untagged and the voice vlan tagged and no other vlans enabled.

vlan 100
  tagged 1-18,20-21,23-24,27-28,Trk1
  exit

 

I hope this helps anyone else that may run across this.

 

View solution in original post


All Replies
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MVP Guru Elite

Re: Voice VLAN assignment via LLDP

for me, there is also the vlan tag number

 

What the voice phone do you have ?



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PowerArubaCP: Powershell Module to use ClearPass API (create NAD, Guest...) More info

PowerArubaCX: Powershell Module to use ArubaCX API (get interface/vlan/ports info)

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ACMP 6.4 / ACMX #107 / ACCP 6.5 / ACSP
Highlighted
Occasional Contributor II

Re: Voice VLAN assignment via LLDP

Cisco 7962 phones for the site in question.

Highlighted
Occasional Contributor II

Re: Voice VLAN assignment via LLDP

I'm going to answer my own question since we just deployed them in production at a customer site.

Yes it works.  It is still a bit unclear what combination of factors makes it work but it basically should boil down to 3 things.

 

LLDP should be enabled.  We actually added...

lldp top-change-notify 1-28
lldp enable-notification 1-28

but I doubt those are necessary to make this work.

 

The vlan configuration should include the voice parameter as shown below.

vlan 100
  name "Voice"
  voice
  exit

 

The vlan configuration should list the ports with phones as being tagged.  This may include ports like those connecting another switch or router as well but for the ports with phones you would normally only have the data vlan untagged and the voice vlan tagged and no other vlans enabled.

vlan 100
  tagged 1-18,20-21,23-24,27-28,Trk1
  exit

 

I hope this helps anyone else that may run across this.

 

View solution in original post

Highlighted
All-Decade MVP 2020

Re: Voice VLAN assignment via LLDP

This was driving me crazy trying to test out the MED location options.

 

It turns out the switch will not send the MED TLVs unless it detects a MED CLASS capability bit with an attached voice policy from the client.  I only tested with Class 3 set so I'm unsure if other classes can elicit MED TLVs, but sure enough once that bit was set it started pumping out the location TLVs.  Why you'd want to turn off MED TLVs based on the client's behavior is beyond me, since LLDP clients are generally pretty good at ignoring unknown fields, but that's how the switches behave apparently.

 

So whether this works can depend on the client used to test.  Most phones probably set the correct bits but there could be others that don't, and test LLDP clients used for debugging/verification need to be configured to pretend to be a phone.

 

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