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Qos Design Question

I am planning to implement QOS on the network for Voice, Data. In my opinion, i would like to keep it simple just using MQC and only classify, mark and priotises the traffic as the traffic is routed between trust boundries.

Data is give higher priority

Second is Voice

Multicast

Video Conf.

shaping retains excess packets in a queue. is this in memory? will this slow down our switches?

Using Policing will means Traffic policing propagates bursts. When the traffic rate reaches the configured maximum rate, excess traffic is dropped or remark. right? Is this the right thing to use.

Is it just better to just classify, mark and priotize without reserving fix bandwidth or queuing in buffer? i know switches have built in queue to queue traffic based on markings.

Please advise.

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Re: Qos Design Question

hi!

" Is it just better to just classify, mark and priotize without reserving fix bandwidth or queuing in buffer? i know switches have built in queue to queue traffic based on markings. "

When you say "prioritize" , it has to do queueing. It is implicit. Only if there are queues, can you give priority to some traffic over other. Else it would be first in first out; right??? Also the "built-in" queues have to ve configured to meet your requirements so that certain markings end up in queues that you want.

Secondly, when you use "bandwidth" command in MQC, you are guaranteeing the minimum bandwidth that the class should get. This will kick-in when there is congestion and all classes are competing for the interface bandwidth. In case there is no congestion and bandwidth available on the interface, other classes can use that excess bandwidth and go well beyond their allotted bandwidth share. So its not like you are "fixing" the bandwidth but rather guaranteeing the min. mandwidth during congestion so that other classes wont starve the class.

"shaping retains excess packets in a queue. is this in memory? will this slow down our switches? "

This queueing is done in hardware. So it wont be utilizing the CPU and wouldnot slow down the device.

"Using Policing will means Traffic policing propagates bursts. When the traffic rate reaches the configured maximum rate, excess traffic is dropped or remark. right? Is this the right thing to use. "

Policing is "usually" used in the ingress direction. The typical scenario is where an ISP wants to limit his customer to his allotted share of bandwidth. He will use ingress policing.

Shaping on the other hand is usually used in egress direction. eg the customer will use egress shaping in the above scenario so that he is able to smoothen out his traffic and bursts which would otherwise be dropped by the ISP.

Also as an advice, in your above config, you can consider giving more priority to voice than data as voice is delay and jitter sensitive while data is not. You may give more "bandwidth" to data traffic but "ptiority" should be more to voice or else there will be problems in the calls.

Hope I answered your questions. Please rate the posts if I did.

Regards,

Niranjan

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