Cisco Hierarchical Queuing Framework

Fair queue?? MPLS ports generally terminate at ethernet or high speed ports. Fair queue is applicable only for ports whose capacity/bandwidth is <2Mb. For anything greater than 2mb speed default queueing is FIFO.

Although you can use fair-queue in high capacity ports, it's not recommended. (except qos)

For each interface the queue length in cisco can be 0 - 4096 max. However this is guided by the amount of memory you have in the hardware.

In HQF, when you enable fair queuing, the default per-flow queue limit is ¼ of the class queue limit. If you do not enable the queue limit in a class, the default per-flow queue limit is 16 packets (1/4 of 64).

Best,

I am not very conversant w/ fair queue... can you please let me know the link which advises on what type to use based on BW... how do we set it to FIFO..

Also, my thought was that the default queue limit was 80,, is it 64 ?

You do not need to set fair queue or fifo in any interface. Any interface <2mb uses fair-queue by default and >2mb interfaces uses fifo by default.

The other option is in the QoS. In the policy map you define fair-queue.

I believe you are asking specifically about the QoS Hierarchical Queueing. It's a different story then.  If you need help in developing or tuning any particular QoS, please paste it here. Answers would be more specific.

Yes.. I want to know more on QoS Hierarchical Queuing. Below is the config that I am looking at:

 class class-default
    fair-queue
    fair-queue queue-limit 120
policy-map vpn_<policy-map>
 class class-default
    shape average 50000000 960000
    service-policy <vpn_output_policy>
!

I hope you understand that in a thread it's not possible to explain up something like QoS, even if anyone tries it will sound more hebrew. The only way would be to read and try understanding. I am not sure how much it will be of help to you, but following link has the materials you are looking for.

http://www.cisco.com/en/US/docs/ios/qos/configuration/guide/qos_frhqf_support.html

I believe it will take you several hours of reading if you really want to understand the meaning of the simple block which you have pasted.

Best,

Surbabu;
All I wanted to know if there is any cisco association for the fair Queue depth and the size of the MPLS port.. how should the queue depth increase or decrease w/ increase in port size (say from 50M to 80M)? Is it trail and error or linear etc.

ok, in lieu of whatever you pasted it has got NO relation with MPLS or non-MPLS. It is a generic HQF statement and is transparent of the technology (MPLS/non-mpls) i.e you can apply it to any interface irrespective of what it's running. (except frame relay).

queue-limit is 4096 in cisco ios and it's fixed. If you type " fair-queue queue-limit  ?" you should see max size is 4096.  Depending on your HQF requirement you type the value e.g here 120. These values will affect your performance.

Best,

How does it vary? If default is 64 it will be 64 always unless you define explicitely. Are you asking what are the basis to choose it to another value?

yes sir.. does this increase w/ the higher throughput, if yes, by how much..
say port is increased by 10M, should fair queue increase by 5, or 10????

Oh no no......absolutely NO.

This value is a part of QoS design. The person who is designing the QoS can put this value to e.g 100. But I can achieve it with 50 and someone will achieve the same result without using fair-queue value at all.

This value is directly related to your QoS performance and need not be necessarily increased/decreased with speed/bandwidth. It has got no effect on your speed/throughput.  It only affects your QoS and subsequent packet flow.

I would suggest do not touch this, unless you know what you are doing.

Well Surbabu; what if we are starting afresh.. how do we assign a figure to this paramter?

You need to tell us exactly what you are looking for and why. Probably the way you are thinking is not right, we can offer a better way.

Fair-queue has got virtually no role now a days and does not affect anything.

shape average 50000000 960000---> 960000 is not suppose to be typed there. It's auto calculated.

Surbabu;
Are you located in US by any chance? I was wondering if I can call you sometime...

You can mail me at sur_babu@yahoo.com, I can provide you my US number.

Best,

Thanks for your help..

Thanks..