01-26-2011 02:29 PM - edited 03-07-2019 12:36 AM
Good afternoon, over the next few months I will be implementing voice over our corporate network. There is existing QoS config on our routers that a consultant added to prefer Video packets from our video-conferencing equipment over other network traffic. Here is this config:
class-map match-any Voice-Video
match ip precedence 5
class-map match-any ERP
match access-group name ERP
class-map match-any Control
match ip precedence 3
!
!
policy-map MPLS-QOS
class Voice-Video
priority percent 50
set ip precedence 5
class Control
bandwidth remaining percent 25
set ip precedence 3
class ERP
bandwidth remaining percent 75
class class-default
fair-queue
random-detect
I am new to this and my questions are the following:
What is this config actually doing?
Should I separate the "Voice-Video" class and somehow prefer voice over video?
Does the router somehow implicitly know what the class "Voice-Video" means?
Will this give me the recommended measurements of Delay under 200ms and Jitter under 30ms
Sorry for the all the questions all at once but I'm trying to gain a firm understanding of this...
01-27-2011 07:21 PM
Hi bsciarra1,
I'm not a QOS expert, however I try to help here with my understanding, feel free to correct me if I'm wrong.
Does the router somehow implicitly know what the class "Voice-Video" means?
as you can see, under class map for voice-video, any traffic with Ip precedence 5 will be "categorize"
as Voice-video class.
then under policy-map, class voice-video, up to 50 percent of the link can be dedicated for this class,
however it has another action here to set the traffic to Ip precedence 5, reason for this is some time when
this policy applied on your wan interface and your provider require you to remark the QOS traffic according
to their class which probably less granularity than you have in your internal network.
the bandwidth remaining percent 25 and 75 refer to the residual bandwidth which is for ERP and Control class
after the 50% reserved link bandwidth. Take a look on the info below from Cisco.
Specifying the Bandwidth Percentage
The following example uses the priority percent command to specify a bandwidth percentage of 10 percent for the class called voice-percent. Then the bandwidth remaining percent command is used to specify a bandwidth percentage of 30 percent for the class called data1, and a bandwidth percentage of 20 percent for the class called data2:
policy-map policy1class voice-percentpriority percent 10class data1bandwidth remaining percent 30class data2bandwidth remaining percent 20As a result of this configuration, 10 percent of the interface bandwidth is guaranteed for the class called voice-percent. The classes called data1 and data2 get 30 percent and 20 percent of the remaining bandwidth, respectively.
source:
http://www.cisco.com/en/US/docs/ios/12_2t/12_2t2/feature/guide/ftLLQpct.html
Hope this helps.
Cheers,
Alex
Please rate helpful post.
01-27-2011 09:47 PM
Hi,
What is this config actually doing?
The configuration is prioritizing voice traffic(50% of bandwidth) and after that voice signal and ERP of the remaining bandwith(need to check ERP acl)
Should I separate the "Voice-Video" class and somehow prefer voice over video?
The configuration only works for voice, you need to add another class-map for video if you like.(precedence 5 is voice, precedence 4 is video)
refer to:
http://www.net-grp.com/2010/01/19/useful-tips-about-quality-of-service-qos-on-cisco-devices/
Does the router somehow implicitly know what the class "Voice-Video" means?
Nope! that's just a name.
Will this give me the recommended measurements of Delay under 200ms and Jitter under 30ms?
Need to check your interface bandwidth and quality of your provider as well, there is no guarantee, but it is not a bad config!
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