MQC Question

Hello all,

I need some clarification with respect to Modular QoS CLI commands.

Take for instance, I have the following requirements

1. Class VOICE, match with dscp AF42, to get 40% of available bandwidth (with priority)

2. Class VIDEO, match with dscp AF22, to get 30% of available bandwidth

3. Class OTHERS, match with dscp AF11, to use remaining bandwidth without any guaranteed bandwidth.

Please look at the following commands:

 

class-map match-all OTHERS

 match  dscp af11

class-map match-all VIDEO

 match  dscp af22

class-map match-all VOICE

 match  dscp af42

!

policy-map ALL_TRAFFIC

 class VOICE

  priority percent 40

 class VIDEO

  bandwidth 30

 class OTHERS

 

My question is with the policy that will be applied to the class OTHERS. 

1. When nothing is configured under the class OTHERS, will it have the same effect as class CLASS-DEFAULT with FIFO queueing?

Or do I need to calculate the remaining bandwidth and the apply it to the class?

2. What effect does this have on the CLASS_DEFAULT class? Will the remaining bandwidth be shared between class OTHERS and CLASS_DEFAULT?


3. Is it compulsory to define/configure class CLASS-DEFAULT under all policy-maps?


Im kind of confused. Can someone please help me out.


Thank you.

 

Comments

  • What's the reasoning behind not configuring a bandwidth statement under a user-defined class? Is there a real-world use scenario for that?

    Without an explicit bandwidth statement, I believe class OTHERS will be allocated BW of 0, which means no packet from this class will get through whenever there is a congestion on the link. This is NOT to say that traffic from class OTHERS will be merged into the default class.

    By default, class-default use flow-based fair-queuing. You can change that by assigning a bandwidth statement for it, in which case it will use FIFO queuing.

    Class-default is not mandatory.

    Just my 2c.

  • Hari.sapkotaHari.sapkota ✭✭ ✭✭

    1. When nothing is configured under the class OTHERS, will it have the same effect as class CLASS-DEFAULT with FIFO queueing?

    As per my understanding, FIFO is the queueing method within the specific class.

    Or do I need to calculate the remaining bandwidth and the apply it to the class?

    You could also have "bandwidth remaining percent" approach for the very specific cases, bu I think your configuration works fine, not tested ;)

    2. What effect does this have on the CLASS_DEFAULT class? Will the remaining bandwidth be shared between class OTHERS and CLASS_DEFAULT?

    I think yes, the class-default & the remaining classes having not bandwidth set is served after the priority queue is empty.


    3. Is it compulsory to define/configure class CLASS-DEFAULT under all policy-maps?


    Im kind of confused. Can someone please help me out.

    Control plane trafics are usually matched with the class-default. So, I think it's important for a class-default to exist under the policy map.

    Any additional suggestion/correction will be highly appreciated. :)

    Thanks

     

  • What do you want to do with the rest of traffic that was not matched by VOICE/VIDEO/OTHERS ?

    If you want to keep the rest of traffic, then maybe you do not need class OTHERS, you can just configure class-default that will collect all traffic that are not VOICE/VIDEO, and it will treat them with WFQ, using the remaining bandwidth.

    If you want to block the rest of traffic, then you need to configure "bandwidth remaining 30" under class OTHERES, and configure a class BLOCK and match the rest of DSCP and apply drop command under the class BLOCK in the policy map.

     

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