CBWFQ and LLQ

Answered Question
Jun 5th, 2007
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Hi, I understand that LLQ is an extension of CBWFQ and is a strict priority class but I am unable to find information as to how to assign traffic flows/types to the LLQ queue. Is this done by a command of some sort e.g setting a DSCP value? Or does the router automatically assign traffic flows to the priority class itself? I think it may have something to do with the EF DSCP value, but I am not certain.


Thank you in advance.

Correct Answer by royalblues about 9 years 9 months ago

Yes you are correct.


LLQ is an option applied to CBWFQ under one or more classes. CBWFQ treats these classes as strict priority queues and always services packets in these classes.


HTH, rate if it does

Narayan

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royalblues Tue, 06/05/2007 - 20:47
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Friend,


The traffic flows are assigned to the LLQ using the "priority" command under the policy map.


When you do QoS for giving priority to a certain traffic, you need to classify that traffic. DSCP is just one way of doing it. Additionally you can also set/mark the DSCP values


eg..


class-map match-all voice

match ip dscp ef


policy-map LLQ

class voice

priority 512


class class-default

fair-queue


HTH, rate if it does

Narayan

voiper_99 Tue, 06/05/2007 - 20:53
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Ahh I see what you mean. So what you are saying is that the bandwidth assigned to the policy map (with the priority command) gives that policy map a slice of the "strict LLQ priority queue". Is that correct?


By the way thank you for the quick reply.

Correct Answer
royalblues Tue, 06/05/2007 - 21:04
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Yes you are correct.


LLQ is an option applied to CBWFQ under one or more classes. CBWFQ treats these classes as strict priority queues and always services packets in these classes.


HTH, rate if it does

Narayan

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