How Can We Use AutoQoS to Protect Voice and Video Traffic?

crossroadsintersection168814997Many companies are already using Voice over Internet Protocol (VoIP) while incorporating video capabilities into their portfolio of services. One question that I am often asked is, “How can we ensure that the voice and video quality is good and consistent when using VoIP?”

That is an excellent question and one that should be addressed during the design phase of the project. Too often, when I teach QOS – Implementing Cisco Quality of Service, I hear students say that they are attending the class because their voice or video is not working well and they now need to implement Quality of Service (QoS) configurations to fix it, which underscores the fact that QoS should be implemented on the network before voice or video is integrated.

So, what exactly is this QoS thing and how complicated is it to implement? The answer varies, depending on whether you are concerned only with protecting the voice and video traffic or whether you also need to consider resource allocation to other, non-real-time applications.

At its simplest, you can use an automated feature in the Cisco environment called AutoQoS VoIP. This feature automates the configuration of QoS to protect voice (and more recently, video traffic) from competing applications.

At its most complex, you will manually configure QoS tools across your network and adjust the QoS environment to meet your applications’ needs. To complete this task, you must understand which applications are running in your network, know the applications’ requirements, and identify which network resources are available to commit to each application. This requires a high degree of knowledge and understanding of your network and its environment.

In this discussion, we will discover how AutoQoS can be used to quickly and easily provide a consistent resource allocation scheme to protect your real-time traffic.

AutoQoS is beneficial for small to medium-size businesses that lack expertise and staffing required to plan and deploy a full scale QoS implementation, as well as larger customer implementations that require consistent, basic and rapid deployment across large enterprises to ensure proper treatment of voice and/or video traffic.

AutoQoS is simple to deploy. Network administrators enter a single command (auto qos voip or auto qos video) per interface across their network. Depending on the platform (switch vs. router) and the interface (edge-facing vs. network-facing), there will be different options that can be specified with this single command.

The macros associated with the AutoQoS command will verify available bandwidth and the underlying Layer 2 technology, and then create appropriate class maps and policy maps, as well as tune the interface specific settings (if required). One requirement includes having the correct bandwidth setting on each interface so that AutoQoS will recognize which configurations to apply.

The original AutoQoS VoIP capability provided treatment for only voice and signaling traffic types.

In August 2010, Cisco updated the AutoQoS capabilities on Catalyst 2960-G/S, 2975-GS, 3560-G/E/X and 3750-G/E/X family of switches with the Cisco IOS release 12.2(55)SE to encompass different Medianet traffic types. This is referred to as AutoQoS-SRND4, which is based on the Solution Reference Network Design guide version 4 that defines these new options. Initiatives continue at Cisco to extend these Medianet AutoQoS capabilities to a broader range of switching platforms.

One of the new options provides automatic configuration support for video traffic, recognizing both Cisco TelePresence Systems (via the cts keyword) as well as IP video surveillance cameras (via the ip-camera keyword).

AutoQoS VoIP/video does not limit the administrator from further tuning the environment if required. Once AutoQoS is configured, the resulting class maps and policy maps can be copied and changed according to specific requirements.

With AutoQoS for VoIP or video, all traffic other than voice, video and signaling is identified as default traffic and is provided access to all unassigned or available resources

If any of the default traffic needs to be identified and provided with guaranteed resources, then the administrator can extend the configuration to include these applications as well.

In summary, AutoQoS VoIP/video can be deployed quickly and easily across any size enterprise to provide guaranteed and consistent treatment of voice and video traffic. It can also be used as the starting point for more complex and specific QoS implementation when companies have the expertise to expand on the resulting AutoQoS configuration.

Related Courses
CVOICE – Implementing Cisco Unified Communications Voice over IP and QoS v8.0
QOS – Implementing Cisco Quality of Service

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1 comment

  1. Khalid Iqbal Ansari Reply

    Voice and video are delay sensitive traffic so it is essential to provide a sufficient amount of bandwidth to such traffic for a distortion free transmission.
    Auto qos reserves some amount of bandwidth for voice and video so at any time X amount of bandwidth will always be available for voice and video traffic from total bandwidth available. Reservation of bandwidth is not enough auto qos also creates a one priority queue class for voice and video and a one custom queue class for remaining traffic,
    With priority queue [EF bit is set (Expedite Forwarding)] so that voice and video traffic will always be serviced/Forwarded first.

    Thanks.