MQC Priority queing

[victor_87]

Hello,

I have a small query regarding QOS Priority queuing and Shaping using MQC.

Lets say i have 10 Mbps total bandwidth. and have 2 different types of Bandwidth which can be matched using ACL's.

The first class i have is highest priority for me and i anticipate that it will need 2 Mbps peak Bandwidth. It is not mandatory that there would be 2 Mbps bandwidth at all times.

The rest of the traffic can all be matched using the class-default and i want that traffic shaped to whatever bandwidth is remaining.

Now my questions are :

- Will the traffic in the default class be able to use the bandwidth in the priority queue when there is not much bandwidth being used by the class that is defined with the priority queue?

- If the answerto the above is NO, then i will probably have to shape the rest of the traffic to the remaining 8 Mbps but if the answer is yes, what will the shape average number i should use. I do not want to over configure the shaping bandwidth to a higher value and loose traffic when bandwidth is not available.

Class-map A

match access-group name ABC

Class-default

Policy-map X

Class XX

priority 2000

class class-default

shape average XXX

Thanks in Advance.

[Joseph W. Doherty · Accepted solution]

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The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

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Posting

Normally you would use a hierarchal policy to accomplish this.

e.g.

class-map match-all llq

match . . .

policy-map parent

class class-default

shape average 10000000

service-policy child

policy-map child

class llq

priority percent 20

interface gt10Mbps

service-policy output parent

[victor_87]

Thank you for your response. That was really helpful.

So what happens first. Do policies take effect in a top to bottom order in a policy or will the Priority Queue still happen first with Highest priority and then the rest.

Victor

[Joseph W. Doherty]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

Yes, policy map classes are matched sequentially.

How what I posted works, if traffic is below shaped rate, traffic just passes through interface.

If traffic rate exceeds the shaped rate, all traffic is queued and dequeued at the shaped rate.  How packets are dequeued depends on the policy.  Any packets in a LLQ will be transmitted before any other queues.  (NB: LLQ when being queued, if they exceed their own rate, excess will be dropped.)