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New Member

Qos -LLQ (1PQ+ CBWFQ

hi,

I have 1 PQ (LLQ) and 4 CBWFQ) in my configuration. I alloted bw 80% LLQ with cir and remaing 20% amonng other 4 CBWFQ.

I have one doubt:

This will support the allocation of unused bandwidth of PQ and WFQ classes to other WFQ classes.

OR

allocation of unused bandwidth of only WFQ classes to other WFQ classes.

Thanks in advance.

Rgds

Chintan

5 REPLIES

Re: Qos -LLQ (1PQ+ CBWFQ

Hi,

queueing will only be active, when you have an overload situation on the interface. Thus even best effort traffic can take 100% of your interface bandwidth, when there is no congestion.

In case there is congestion the bandwidth available will be distributed between all traffic classes, where there are packets waiting to be serviced. So bandwidth will always be "allocated" to all traffic classes. This includes free capacity from the PQ.

Hope this helps! Please rate all posts.

Regards, Martin

New Member

Re: Qos -LLQ (1PQ+ CBWFQ

In addition to the previous post, you also have to remember 1 other thing: by default, Cisco routers only allows you to "slice up" up to 75% of the actual interface bandwidth, to prevent your inadvertently starving class-default traffic. Therefore, if you already include class-default in your CBWFQ, and allocated a specific b/w percentage to it, you can configure "max reserved-bandwidth 100" on the interface where CBWFQ/LLQ applies.

One curious question: why did you allocate so much bandwidth to your LLQ?

New Member

Re: Qos -LLQ (1PQ+ CBWFQ

Hi,

Answer to your question :

My LLQ is voice traffic and I have this Qos applied in Mobile (CDMA) Network for transport where most of traffic is voice calls/Data calls thats why i have 80% is in LLQ.

Does it make sense ? Any suggestion ?

Rgds

Chintan

New Member

Re: Qos -LLQ (1PQ+ CBWFQ

One really important caveat that was not completely clear to me until recently is that unless you specifically call out a bandwidth or bandwidth percent in your class default, the other defined classes are capable of starving out the class default. Aparently the algorithm is written such that the defined bandwith queues can utilize any remaining bandwidth before the default queue. (this is reguardless of the fact that there is an implied minimum 25% allocated to the class default)

New Member

Re: Qos -LLQ (1PQ+ CBWFQ

Hi,

Yes you are right. But i have put reamining bandwidth in all other CBWFQ class including default according to requirment.

Let me share the configuration:

I'm still testing this with my requirment and design.

policy-map llq-policy

class class1_x ------> Voice callson CDMA

priority

police cir percent 90

conform-action transmit

exceed-action drop

class class2_x

bandwidth remaining percent 63 -->

queue-limit 128

class class3_x ---> other protocol

bandwidth remaining percent 6

queue-limit 128

class class-default ---> default like other traffic FTP etc.

bandwidth remaining percent 31

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