QoS Architectural Question for LAN

Beth,

Configuring QoS for your scenario is pretty complex task. Here is what should be considered:

1. Call Admission Control for your Conferencing Units (to allow only certain number of conferences, depending on bandwidth).
2. Configure proper Audio and Video codecs for Conference Units (keep balance between quality and number of calls)
3. Configure proper DSCP and CoS marking for Video and Audio streams (it should be configured as close to source, as possible)
4. Configure proper QoS scheduling and queuing for LAN switches (and trusting traffic which is already marked)
5. Configure your WAN (MPLS) routers with proper QoS (re-marking for MPLS, queuing, prioritization, etc.)
6. Confirm from the provider that they will comply with your QoS traffic marking and will honor it.

In general, QoS should be configured everywhere, on each and every device traffic touches, or that unit will eventually become a bottleneck.

Good luck,

Mike CCNP, CCDP, CCSP, CCVP, MCSE W2K, MCSE+I, Security+, etc. CCIE Voice (in progress), CCIE R&S (in progress)

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Thanks!

3-4 -- Looks like I need to handle this.

I appreciate your response.

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My (very) limited experience of QoS on Cisco is that the features all look pretty cool in the marketing blurb and in the manuals but that there seems to be wide variation between platforms on what exactly works and what does not. The latter does not seem to be documented very much. e.g. The 3750 supports Modular QoS commands - but ONLY for Input Policing and Marking. Output QoS is by various archaic mechinisms where you have to configure queues individually and send packets to queues yourself.

For a project such as you describe I would want to see it all humming away in a lab before committing to delivery.

I would be very wary of the Sup2/MSFC just 'cos it has been around for a while.

My (very) limited experience of QoS on Cisco is that the features all look pretty cool in the marketing blurb and in the manuals but that there seems to be wide variation between platforms on what exactly works and what does not. The latter does not seem to be documented very much. e.g. The 3750 supports Modular QoS commands - but ONLY for Input Policing and Marking. Output QoS is by various archaic mechinisms where you have to configure queues individually and send packets to queues yourself. For a project such as you describe I would want to see it all humming away in a lab before committing to delivery. I would be very wary of the Sup2/MSFC just 'cos it has been around for a while.

It's not that scary as it looks at the first glance. Almost any modern Cisco switch (I mean with decent software version) has a feature called "Auto QoS", which in most cases does everything for you. In general, for the LAN there is one consideration - don't let the switch to strip or modify QoS information, which is set by the endpoints. Like if Video Conference Station set certain DSCP and/or CoS parameters, switch should trust that marking. If endpoint did not set these parameters, then it gets a little bit more complicated, as switch should recognize traffic and set appropriate DSCP and CoS values. Also, there should be a consistency between what set at the endpoint, what expected on the router, and what trusted by MPLS cloud.

Good luck,

Mike CCNP, CCDP, CCSP, CCVP, MCSE W2K, MCSE+I, Security+, etc. CCIE R&S (in progress), CCIE Voice (in progress)

------ Headset Adapters for Cisco IP Phones

Phoneswww.ciscoheadsetadapter.comwww.headsetadapter.com

With so many good points already raised, I'll just add this...When you are looking at your WAN QoS settings, you will need to let the Telco know how much bandwidth to reserve (during congestion) for each class of traffic, which they typically do by looking at IPPrec bits, not the entire DSCP byte.

Also consider how your markings will be handled. Verizon, for example, will take your DSCP values of 32,34,36,38 and put them all into the same queue, with no WRED on ingress. On egress, they will use WRED, which takes into account your DSCP markings. I'm pretty sure they don't they remark anything.