Setting up QOS in for video conferencing.

The most important thing is to understand your traffic profiles (what kind of traffic, how much, from where, to where and how does it go), link utilisation, queueing capabilities of the devices (how many queues supported, scheduling of transit and self-originated traffic), how to treat traffic on L2/L3 devices (i.e. do routers need to care about 802.1p settings or not). Bear in mind that QoS configurations kick-in only when there is congestion (that is when there is no space left in TX-ring buffer, which is often much before your link is 90% loaded), all other time it's FIFO. Also, enabling QoS does increase load on the devices, and more so if configuration is suboptimal.

While you don't actually have to enable QoS all the way through the chain, you do need to understand behaviour of the equipment when they don't have QoS configuration explicitly applied. Obviously the overloaded 2Mbps links are the first one where you should consider deployment of QoS policies, while barely loaded gigabit links will hardly show any difference with or without QoS applied.

If you have more specific questions - feel free to ask.

As for general reading you could start here

or get a book like "End-to-End QoS Network Design" (ISBN: 1-58705-176-1).

Kind regards, iLya

It's always good practice to implement QoS clear through the network path that the video/voice traffic would take. That would include Layer

2 in your core network even if it's gigabit attached. That being said, one thing to remember that QoS only affects traffic on an interface when there's contention for the available bandwidth. (ie. Your link is) Here's some hints... * Bandwidth monitoring will not necessarily show the need for QoS as it's normally monitored on an average over 5 minutes. * If you're using ATM or Frame-Relay, do not oversubscribe the physical link. Cisco's QoS works on a per-interface (or sub-interface) basis. If you oversubscribe the link, all bets are off with regards to QoS. * If your using a managed MPLS WAN, you'll need to work with your provider.

====================================================== There are probably a thousand different ways to implement QoS. Here's a L3 EXAMPLE config for you as requested: (CBWFQ)

PloycomLANrouter-A WAN router-BLANPolycom

Both routers have similar configs so only one is listed here. ====================================================== class-map match-all AUDIO-CLASS match access-group name NEW-AUDIO-ACL class-map match-all VIDEO-CLASS match access-group name NEW-VIDEO-ACL ! policy-map VID-CONF-POLICY class AUDIO-CLASS priority 96 class VIDEO-CLASS bandwidth 320 class class-default fair-queue ! interface ATM0/0.11 point-to-point description PVC to Remote Site ip address 10.1.1.10 255.255.255.248 pvc 1/65 vbr-rt 768 768 oam-pvc manage service-policy output VID-CONF-POLICY ! interface FastEthernet0/0 ip address 10.11.1.1 255.255.255.0 ! ip access-list extended NEW-AUDIO-ACL permit ip host 10.11.1.25 any dscp af41 ip access-list extended NEW-VIDEO-ACL permit ip any host 10.11.1.25 dscp af42 ======================================================

Here's the break down: The ACL's and class-map's are used to classify the traffic. The Policy-map assigns priority and bandwidth according to needs. Then tie it all together on the interface the traffic would exit from. with the service policy.

Remember that any QoS config is specific to the individual needs. - taking in account for bandwidth needs, WAN speeds, etc. The example above does not take in to account anything for routing protocol for example.

J.Cottingim

I wanted to say thanks to all that replied. It has been a good help for me to take the next step.

Thanks again