Recommended QoS for Video Conferencing

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Aug 13th, 2008
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Two Sites are connected by MPLS link with 2MB bandwidth.Both sites have cisco 2811 routers and 3750 Switches .ISP says they have enabled QoS with IP Precedence 5 for platinum CoS.I have enabled MQS on both the routers with set precendence vlaue 5 and applied on MPLS outbound direction.And in switches auto qos is enabled and trusted on Video Coference station port and uplink ports .There are some difference on Jitter and Packet loss but still the packet loss increses sometimes and gives poor video output.

Any suggestions on this to improve video quality.


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Marwan ALshawi Wed, 08/13/2008 - 16:10
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by default the precedence 5 not for video!

have u done the right marking for ur vedio traffic ?

and have u given the right bandwith with regard to the marked traffic END TO END

bothe sides and two direction?

the following link not relating to ur case exactly but its about cisco telepresnce QoS

however it will give good information and guid u through the way

good luck

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mpoonghat Fri, 09/05/2008 - 21:20
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Sorry for the late reply.

Do you have any good document which gives steps to mark the video traffic manually in Edge and Core switches ?

Thanks alot.

Marwan ALshawi Sat, 09/06/2008 - 02:11
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hi Madhu

i think the link i have given to u nice one

and for marking on the edge switch u can either match by source Ip based or u can match the COS,IP precednce or DSCP value of the vedio device u have if it dose marking by default

lets say u matched the traffic by source IP with ACL then class map

for example

lets say the vedio in nework


access-list 100 permit any

class-map vedio-class

match access-group 100

policy-map vedio-pilicy

class vedio-class

set ip dscp 32 or precedence cs4 or cos 4

ans also enable qos globaly on the switch

like mls qos

and on the ulink fron edge to core and on the core link as well trust dscp value

in the interface level


mls qos trust dscp

on the core u cam make matching to the vedio traffic now by useing the dscp vlaue or ip precedence which either 32 or cs 4 based on the marking mde on the edge wsitch

by the way the policy made above need to be applied in the inbound direction the access port for the veiod source

good luck

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