Qos question

Unanswered Question
Oct 28th, 2009
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Dear all

I have some branch offices, they user voip and video conference and also some application.

the problem is video conference need bandwidth but it does not user very day?

how can I garantee bandwidth why its on demand and when the video conference is not in use the bandwidth allocate for other applications

thank you

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huangedmc Wed, 10/28/2009 - 04:01
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On the high level, you need to work w/ your MPLS carrier to make sure you have a suitable QoS policy in the provider cloud, and configure your QoS policy accordingly w/ various priority & bandwidth commands.

Read through the IOS 12.4 QoS config guide:


The design guide should also help:


Joseph W. Doherty Wed, 10/28/2009 - 04:23
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Much QoS is based on the premise that a class or type of traffic is guaranteed a certain amount of bandwidth but often when any of that bandwidth isn't being used it can be used by other traffic.

For example a CBWFQ such as:

policy-map aSample

class VoIP

priority percent 10

class VidConf

priorty percent 20

would guarantee VoIP 10% of interface bandwidth, VidConf 20% of interface bandwidth and guarantee 70% for all other traffic but if VoIP was only actually using 5% and VidConf wasn't active, other traffic could use 95% of the interface's bandwidth. If VidConf became active and used 15% while VoIP was still using just 5%, then other traffic could use as much as 80%, and so on.


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