Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
Community Member

Voice VLAN

I have this setup:

6509 switch connected to multiple 2950 switches. In each IDF I will have atleat (20) 2950 connected to 6500 switch. 6509 then will be connected to 3700 series router for WAN Connectivity. 6509 will also be connected to Nortel CSE1000 IP phone server. The question is:

In each branch I will have atleast 5 or 6 IP phones connected to 2950 switch. I Like to put my 2950 switch ports for phones in a different vlan for voice traffic and will have a separate vlan for Data. Do I need any QOS for Voice port?

The connection between 2950 switches to 6509 will be Gigabit. I believe I have enough bandwidth between the ports, and voice traffic should be okay w/o any QOS.

Is there any specific good link for setup Voice VLAN in 6509 and 2950 switches along with QOS if needed?



Re: Voice VLAN

The link for configuring voice vlans on a Cat 2950 switch is given below. It also contains the QoS configuration. Hope this helps.

Community Member

Re: Voice VLAN

Yes you will want end-to-end QOS for optimal voice performance. 802.1 p/Q at layer 2: vlan and performance tagging. At layer three use diffserv. The IP phones should allow you to accept DHCP site-specific option numbers (sson) for QOS settings, or you can manually configure the phones as a last resort.

Even on the gig link between 2950 and 6509 congestion may occur, it is recommended to 802.1p/Q tag.

Community Member

Re: Voice VLAN

This will probably shock many people that I even suggest this: You most likely won't notice a difference. We have a phone on the Packet Clearing House network, part of the INTER-NOC HOTLINE PHONE SYSTEM, and we run it over our commodity Internet connection with no QoS, and we have no problems. Then there are all the Vonage customers running VoIP over their home broadband connections, do you think their ISPs honor the QoS tags from their Cisco ATA boxes?

Cisco has recently added autoQoS features to its 2950 line, as well as the 6509 CatOS. Configuring it is not difficult, and it makes sense to do it. It would probably be better not to rush the QoS deployment until you fully understand how it works, compared to deploying it incorrectly or not being able to troubleshoot it if there are problems.

Good Luck

P.S. Check out the IP Quality of Service book from Cisco Press, it is a good read

Community Member

Re: Voice VLAN

Hi Peter,

Create a vlan for voice and another for data. Include the nortel box in voice vlan and connect all the ip phones to it. No need to enable the QOS. The number of IP phones you have and the connection being on LAN makes it unnecessary. We have tested this.



CreatePlease to create content