Tagging and QOS for voice on Cisco 2960

ITGIT
ITGIT used Ask the Experts™
on
I have a new Dell 3548P setupfor voice vlan and a gb uplink from there to a gb link on my 2960

I would like to tag all voice traffic coming to Gi0/2 (the Dell 3548P) and get it properlt prioritized and on its way to the internet to a 3rd party VoIP provider.
Comment
Watch Question

Do more with

Expert Office
EXPERT OFFICE® is a registered trademark of EXPERTS EXCHANGE®
mikecrIT Architect/Technology Delivery Manager

Commented:
First thing you need to do is find out what type of QoS that your ISP provides. What you want is an end to end solution. They may use layer 2 EF header or some other packet tagging but you'll need to know before you set it up on your network. If you tag it and they are not running the same thing, you'll only be efficient up to the point where it leaves your network.

Once you find out, then let us know and we can provide you with some sample configurations.

Author

Commented:

Received this from my VoIP provider - have not heard from ISP yet

Hello,

Our Session Border Controllers apply standard audio and video TOS bits to all outbound packets.

However, these packets may not make it to your network depending on your Internet Service Provider, you would have to ask them if they honor TOS.

If they are dropping TOS for whatever reason, you may want to simply prioritize all traffic to/from our network which is 67.192.61.0/24.

We're also about to release the IronVoice" Express Router, basically a call concentrator for larger deployments. It's really slick, we got our production evaluation units last week and we're really excited about it.

Author

Commented:
I just received this from my NEW ISP

I agree with what IronVoice is telling you.  You should go in to your firewalls and prioritize all traffic to/from their network.  
I do not know of any ISP's that offer CoS on internet traffic.  I know that we will not change any packets to strip the TOS bits but it is up to your network gear to act on them.


So it looks as I need to do some changes in the ASA 5510's
Amazon Web Services

Are you thinking about creating an Amazon Web Services account for your business? Not sure where to start? In this course you’ll get an overview of the history of AWS and take a tour of their user interface.

mikecrIT Architect/Technology Delivery Manager

Commented:
If you're using VoIP and sending it across the internet, what is the destination for it? Who is going to recieve it? I'm a little confused as if you're attempting to make a phone call and you route it across the internet, you'll need a some type of voice gateway to receive it on the other end. Since most ISP's don't use QoS on their networks for this type of stuff, as you found out, tagging a packet and sending it across the internet is futile. You don't get ANY QoS, only on your local network. You're going to have problems with call quality if you do this.

Author

Commented:
Mike - look at how Ironvoice.com operates
IT Architect/Technology Delivery Manager
Commented:
I got it. Your phones talk over the internet to their PBX system via VoIP. With no quality of service across the internet, plus the fact that incoming phone calls to their PBX equipment are not prioritized based off of who they come from, I don't think tagging your packets will have much effect. VoIP is an RTP stream that goes in one direction at a time. It uses UDP to send a flow of packets that, if interrupted, could cause poor quality calls, or audio/video for that matter. It doesn't matter how much you compress it, it's still unidirectional and can be influenced by heavy traffic.

With that in mind, you will need to prioritize incoming and outoing voice traffic so that it gets queued and sent first instead of internet traffic. This will help if someone is downloading a big file across the internet. Prioritization will need to take place on the farthest equipment to the ISP. In other words, if you are running DSL and have a DSL modem, whatever device that sets directly behind it will need configured unless it is a multifunction device. In turn each piece of equipment coming back into your network will also be required to support QoS as well and be configured or this won't work. The endpoint QoS device will be the switch that the phone is plugged into. Since your phones have their own vlan and are basically on their own subnet, I would probably prioritize by IP source/destination. Do you know what IP address return calls will be coming from? If someone picked up a phone at home and called your office, what IP address would they show as coming from? This will help with creating your QoS on your network. Also, do your phones have live IP addresses on the internet or are you doing a one to one NAT for them?

Author

Commented:
This is starting to look like I need an in house solution
mikecrIT Architect/Technology Delivery Manager

Commented:
How many phones will you have and how many phone calls per day are you looking at? If done properly, VoIP can provide some serious cost savings but at the expense of quality in some cases.

Author

Commented:
Will be 5 locations and a total of 160 users

Do more with

Expert Office
Submit tech questions to Ask the Experts™ at any time to receive solutions, advice, and new ideas from leading industry professionals.

Start 7-Day Free Trial