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Video QOS Best Practice

Scott Beauton
Level 1
Level 1

Running Cisco VCS with mulitple Video End Points with multiple remote locations.  I'm setting up the QOS for Video on the Routers and wanted to confirm a couple things.  I've seen many posts regarding Video QOS but it seems each answer varies.  Below is the sample config I was going to use.   Should I be using a differnt class-map for dscp EF.  What is the recommended bandwidth I should be using for Video QOS.   Any suggestions on this would be helpful.  THanks

class-map match-any Video

  description ** Video Control and Signaling **

match dscp af41

match dscp cs4

class-map Video-RTP

match dscp ef

!

policy-map QoS-Policy

class Video

    bandwidth 80%

  class Video RTP   

class class-default

    fair-queue

3 Replies 3

Hi Scott,

This should give you an good overview of what are the recommended design guide from Cisco

http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND_40/QoSCampus_40.html

HTH

Rasika

**** Pls rate all useful responses ****

islam.kamal
Level 10
Level 10

Hi

Please find the below table , for EF is used for COS 5 which is reserved for voice traffic .

.

normally recommends this marking scheme for multiservice networks:

Traffic TypeLayer 2 CoSLayer 3 IP PrecedenceLayer 3 DSCP
Voice RTP155EF
Voice control33AF31
Video conference44AF41
Streaming video (IP/TV)11AF13
Data0-20-20-AF23

1 RTP = Real-Time Transport Protocol

Please find also the below link which will help you for video conference

http://www.cisco.com/en/US/tech/tk543/tk757/technologies_tech_note09186a0080094968.shtml

Thank you

please rate all useful information

Joseph W. Doherty
Hall of Fame
Hall of Fame

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Posting

Should I be using a differnt class-map for dscp EF.  What is the recommended bandwidth I should be using for Video QOS.   Any suggestions on this would be helpful.  THanks

Your class-map for DSCP EF (Video-RTP) doesn't have anything defined?

You can use any marking you like, although there are recommendations for different traffic types (which incidentally are slightly different between RFCs and Cisco).  I would advise using either RFC or Cisco marking recommendations.

How the bandwidth is managed, when there's congestion, is the real key to effective QoS policies.  (Markings are just a short cut to ease identification of different traffic kinds.)

What bandwidth you should use for Video depends on the video source's bandwidth requirements, its codec and whether it's real-time or streaming video.  In general, often video is very variable in its short term bandwidth usage, so you either want to allocate excessive bandwidth so it doesn't need to buffer (approach for real-time video) or you need to insure there's sufficient buffering (approach for streaming video).

Real-time video might be placed in LLQ or PQ, although this risks such traffic being adverse to some other real-time traffic like VoIP bearer.  If LLQ or PQ isn't being used, then a high bandwidth ratio might be defined to insure prompt attention from the scheduler.

For streaming video, bandwidth might be defined slightly above the nomimal/average bandwidth expectation, again, though, insure there's sufficient buffering.

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