DSCP Marking for QoS Video and Data traffic

[Ninad Thakare]

Hi,

I have planned for MPLS link detween my 2 locations.

I want to configure QoS on my router for Video and other traffic but My MPLS guys have raised one query, that there should be DSCP marking for the Video and data.

I need what is this DSCP marking Information and why is it so Important...?

Please help.

Thanks in Advance.

Regards,

Ninad Thakare

[sathvik k v]

Hi Ninad,

Refer the below URL for which might give you better understanding on DSCP.  

http://www.cisco.com/en/US/tech/tk543/tk757/technologies_tech_note09186a00800949f2.shtml

Regards,

Sathvik  KV

[John Blakley]

Ninad,

A DSCP marking is used to mark packets as they go out of your network. The mpls provider will, usually, do something with a certain marking. For example, if you mark all http traffic as dscp 21, the ISP (mpls provider) will guarantee a rate for any packet with dscp 21 as a marking. This is where it's important. Generally, the ISP will remark everything to default (dscp 0) if you don't pay them for qos as a service. When they do that, it's best effort for all of your traffic once your packet gets into their network.

So, for this to work, you should get in touch with your ISP to find out what kind of qos service they offer. It's usually set up as a monthly fee, but then your traffic is guaranteed through their network.

HTH,
John

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[Mir Navazish Ali]

Hi Ninad,

Usually Service Providers maintain various Class of Services on their network.

Say For example

Voice - Class1

Video - Class2

Business Critical - Class3

Best Effort - Class4.

Not necessarily they would maintain 4 classes of services, they can maintain 6 classes as well in addition to the control class(they use this class to maintain their control traffic across their backbone).  So in order for your to leverage these segregated queues accross their network they provide this as a service to you with an additional cost.

In order for classifying different traffic profiles into these classes they need some marking on the traffic which is incoming into their network( Through the customer handoff interface). The IP Precedence / DSCP marking provide this capabilities to the ISPs for this requirement, through which they would be able to understand which traffic needs to be put on which Class(queue).

In order to technically leverage it you need to request your ISP to provide their CoS mapping which consist the DSCP to Class of Service Mapping. After you receive this information, you would need check what is the DSCP marking required for Voice and Video and map it accordingly for the traffic which is going over to the ISPs Provider Edge device.

I hope this help.

Thanks

Mir

[Ninad Thakare]

Hi,

Thanks for the reply.

But how can I understand the DSCP values or Class which need to be mention.

Regards,

Ninad Thakare

[Mir Navazish Ali]

Hi Ninad,

You should be able to get the DSCP to Class of services mapping from your service provider itself.