03-15-2011 02:19 PM - edited 03-06-2019 04:06 PM
I have been reading through the lots of docs on how about configuring voice vlans on cisco switches, but almost all of them assume you have cisco IP phone. I can not find a definitive guide on how to configure voice vlans with non cisco phone, no CDP. I have the following setup
PC ---- IP-PHONE ------ Catalyst 2950
The PC and the phone are on 2 different subnets
I have read lots of docs on how to create voice vlans.
some say
switchport access vlan 100
switchport voice vlan 200
But I read somewhere that only works when there you CDP enabled phone.
I have come across
switchport trunk allowed vlan 100, 200
switchport mode trunk
switchport voice vlan 200
I am confused as to which way to proceed. Some even say you have to configure dot1p encapsulation on the ports as well. My phone can tag traffic originating from itself with vlan and priority. So which would be the best way to go?
Many Thanks
Solved! Go to Solution.
03-15-2011 03:04 PM
Hi mate!
For non-cisco IP phones which do not support CDP you can configure a static trunk - which is what you have found in your research.
At a high level - in the Cisco world, when a Cisco IP phone is connected to a Cisco switch - the Cisco phone uses CDP to automatically detect and create a "internal trunk" that can identify 802.1q tagged traffic - for the voice vlan. Data VLAN is typically untagged.
In this light - non-cisco IP phones work in a similar fashion, so to simulate the internal trunk that is created via CDP we would configure a static trunk.
Configuration:
switchport trunk allowed vlan 100, 200 <<---- this makes sure that phone does not get traffic from other VLANs when in trunk mode
switchport mode trunk
switchport voice vlan 200
switchport trunk native vlan 100 <<---- I would try this for the Data VLAN traffic
mls qos trust cos <<---- to trust the priority from the phone.
I've seen this a lot on the older 3rd party IP phones which did not support CDP.
HTH
Eugene
03-15-2011 03:39 PM
Hi Saiyen,
By default, on Cisco switch, a 802.1q trunk will have a native VLAN of 1 (but doesn't show up in the config). Also, by default, a trunk will carry all VLAN's.
Typically, for Cisco phones - the data VLAN traffic is not tagged and untagged traffic will be switched through the native vlan. So, if you wanted the data VLAN to be 1, I would remove the
switchport access vlan 100
simply because it confuses people who look at the config :). In the context of your configuration, because the port will be a static trunk, it specifies that the access port will be in VLAN100 if in ACCESS mode. In TRUNK mode, it is not taken into account.
I did a quick search in google and found:
http://wiki.snom.com/Web_Interface/V7/Advanced#VLAN
It looks like you can tag the data vlan traffic if you wish
HTH
Eugene.
03-15-2011 04:15 PM
Hi Saiyen,
Yes, that's it! Configure the switchport access vlan 200 for the Asterix port to have the Asterix on the Voice VLAN.
You may need to consider a QoS config such as
#mls qos trust dscp -> if there's a QoS value for signalling traffic from the Asterix (which there should be).
HTH
Eugene.
03-15-2011 02:42 PM
switchport access vlan 100
switchport voice vlan 200
You need to use this.
Don't forget that if you create VLAN 100 and 200, you need to create the VLAN instance.
03-15-2011 03:09 PM
Thanks leolaohoo. What if I want my pc data to gon on the default native VLAN1. Do I still have to do switchport access vlan 100?
Also, how would I configure the port that is connected to my PBX. I am using asterisk trixbox which will be on the same subnet as the IP phones. I need my IP phones to log into the PBX, so would I configure the port as a simple access VLAN on the same port as the voice VLAN. Like switchport access vlan 200?
Thanks
03-15-2011 03:04 PM
Hi mate!
For non-cisco IP phones which do not support CDP you can configure a static trunk - which is what you have found in your research.
At a high level - in the Cisco world, when a Cisco IP phone is connected to a Cisco switch - the Cisco phone uses CDP to automatically detect and create a "internal trunk" that can identify 802.1q tagged traffic - for the voice vlan. Data VLAN is typically untagged.
In this light - non-cisco IP phones work in a similar fashion, so to simulate the internal trunk that is created via CDP we would configure a static trunk.
Configuration:
switchport trunk allowed vlan 100, 200 <<---- this makes sure that phone does not get traffic from other VLANs when in trunk mode
switchport mode trunk
switchport voice vlan 200
switchport trunk native vlan 100 <<---- I would try this for the Data VLAN traffic
mls qos trust cos <<---- to trust the priority from the phone.
I've seen this a lot on the older 3rd party IP phones which did not support CDP.
HTH
Eugene
03-15-2011 03:16 PM
Hi Eugene,
Are you saying that the simple way of
switchport access vlan 100
switchport voice vlan 200
will not work at all? Or that the method you mention is the better one. My Snom360 IP Phone, does not have CDP, but it can tag the traffic with VLAN and priority.
Also, If I want my data to go on the default native VLAN1, i assume I can skip the line switchport trunk native vlan 100?
03-15-2011 03:39 PM
Hi Saiyen,
By default, on Cisco switch, a 802.1q trunk will have a native VLAN of 1 (but doesn't show up in the config). Also, by default, a trunk will carry all VLAN's.
Typically, for Cisco phones - the data VLAN traffic is not tagged and untagged traffic will be switched through the native vlan. So, if you wanted the data VLAN to be 1, I would remove the
switchport access vlan 100
simply because it confuses people who look at the config :). In the context of your configuration, because the port will be a static trunk, it specifies that the access port will be in VLAN100 if in ACCESS mode. In TRUNK mode, it is not taken into account.
I did a quick search in google and found:
http://wiki.snom.com/Web_Interface/V7/Advanced#VLAN
It looks like you can tag the data vlan traffic if you wish
HTH
Eugene.
03-15-2011 03:56 PM
Thanks for that Eugene, I am almost there. One last thing.
How would I configure the port that is connected to my asterisk trixbox pbx? I need the IP phones to be able to log into the pbx which is on the same subnet. There is no tagging coming from the pbx, so would I just simply configure the port as an access port which is on the same VLAN as the voice VLAN?
03-15-2011 04:15 PM
Hi Saiyen,
Yes, that's it! Configure the switchport access vlan 200 for the Asterix port to have the Asterix on the Voice VLAN.
You may need to consider a QoS config such as
#mls qos trust dscp -> if there's a QoS value for signalling traffic from the Asterix (which there should be).
HTH
Eugene.
03-15-2011 04:44 PM
Thanks for all the help Eugene. I will try all this out at work tommorw.
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide