RE: shape on 3560

My conclusion from configuration: from which queue will be more traffic sent when interface is congested

if interface of 1Gbps is congested with:
flow for q1 = 700 Mbps
flow for q2 = 500 Mbps
flow for q3 = 500 Mbps
flow for q4 = 500 Mbps

and the following configuration is on interface:
priority-queue out
srr-queue bandwidth shape 0 5 0 0
srr-queue bandwidth share 1 1 10 10

the result will be:
q1 = 700 Mbps
q2 = 200 Mbps
q3 = 50 Mbps
q4 = 50 Mbps

traffic in q2 has more bandwidth than q3 and q4, so shaped queue is better as we can influence which queue (q2-4) will get more bandwidth if we don't count priority queue.

-----Original Message-----
From: Marko Milivojevic [mailto:markom_at_ipexpert.com]
Sent: Sunday, August 07, 2011 8:44 PM
To: Carlos G Mendioroz
Cc: gp; <ccielab_at_groupstudy.com>
Subject: Re: shape on 3560

What is meant by "not delay guarantee" is that while minimum BW is
guaranteed (for both shaped and shared), there is no priority in
processing the queues. Queueing is a two-step process. First, the
packets are put into the queues and then the queues are serviced
(packets are dequeued). To guarantee the minimum delay, queue needs to
be serviced first. In SRR scheduler, this is not the case for any
non-priority queue. I.e. packets are dequeued in a round-robin fashion
from queues according to their respective weights.

In plain English, if there are three packets in queue 1 and according
to the wights for Q1, we can send only 2, the third packet will have
to wait for Q2-4 to be serviced before it's sent. If the queue was
shaped, it would be in the next scheduled time interval, or if it was
shared, once the queues are serviced up to their minimum guarantee,
packets from all shared queues would be serviced until time interval
elapses, or queues are fully empty.

Contrary to this, when strict scheduling is used (priority queue on
Cats, or PQ and LLQ on routers), priority queue is always serviced
first, regardless of other queues. On Cats and in PQ, you cannot limit
the amount of traffic sent (creating a queue starvation problem), but
with LLQ there is a conditional policer, which prevents this, However,
they all share the same dequeueing strategy - they are always serviced
before any other queues.

Does this make it more clear? For more details - DQOS by Wendell Odom
is a fine start.

--
Marko Milivojevic - CCIE #18427
Senior Technical Instructor - IPexpert
FREE CCIE training: http://bit.ly/vLecture
Mailto: markom_at_ipexpert.com
Telephone: +1.810.326.1444
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On Sun, Aug 7, 2011 at 11:04, Carlos G Mendioroz <tron_at_huapi.ba.ar> wrote:
> Marko,
> you say that all queues have guaranteed BW but not delay.
> I don't fully understand that.
>
> Are you saying that the delay for a packet of some class is not bounded?
> If not, delay is also guaranteed.
>
> If you have 3 queues, one with 50Mb shape and the other two 1/3 the BW
> on a 100 Mb link, anything below congestion (and below 50Mb) will be
> just served, but if the 3 queues try to get 40Mb, what will be the effective
> throughput of each ?
> I would say 40/30/30.
>
> -Carlos
>
> Marko Milivojevic @ 07/08/2011 14:22 -0300 dixit:
>>
>> All queues are guaranteed bandwidth, but not the delay. SRR is round-robin
>> alghoritm. Shaped queues are assigned bandwidth first and whatever remains
>> is used by shared queues, but servicing the data in queues is always equal
>> between all the queues.
>> When you enable PQ, Q1 is serviced until empty and only then Q2-4 are
>> processed according to the SRR configuration and remaining bandwidth in the
>> time interval.
>> --
>> Marko Milivojevic - CCIE #18427
>> Senior Technical Instructor - IPexpert
>>
>> Free CCIE Training: http://bit.ly/vLecture
>>
>> Mailto: markom_at_ipexpert.com
>> Telephone: +1.810.326.1444
>> Community: http://www.ipexpert.com/communities
>>
>> :: Sent from my phone. Apologies for errors and brevity. ::
>>
>>
>> On Aug 7, 2011, at 2:42, "gp" <gs4me2me_at_gmail.com> wrote:
>>
>>> I read somewhere that shaped queue is processed before shared.
>>> Unfortunately cannot find it:)
>>>
>>> Is it possible to guaranteed some traffic bandwidth to be processed
>>> before other with limit in task that it cannot be mapped in priority queue
>>> because some other traffic more important is mapped to priority queue?
>>>
>>> For example:
>>> Q1 - traffic X - priority Q2 - traffic XY - less important than traffic
>>> X, more important than traffic XYZ
>>> Q3&Q4 - traffic XYZ
>>>
>>>
>>> Regards,
>>> Gp
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: Marko Milivojevic [mailto:markom_at_ipexpert.com] Sent: Saturday,
>>> August 06, 2011 10:46 PM
>>> To: gp
>>> Cc: ccielab_at_groupstudy.com
>>> Subject: Re: shape on 3560
>>>
>>> Sharing and shaping has nothing to do with priority queueing. I.e.
>>> shaped traffic is not processed before shared - it's only limited to
>>> certain percentage of the traffic, while shared queues are simply
>>> guaranteed a minimum.
>>>
>>> You can configure shaping as a percentage of negotiated speed, of
>>> course. By default 100% of interface bandwidth (negotiated speed) is
>>> available for all queues. If you want to limit Q2 to say, 33% you can
>>> configure it as "srr-queue bandwidth shape 0 3 0 0". However, if you
>>> want to limit it to say 5 Mb/s REGARDLESS of the negotiated speed,
>>> this cannot be done on 3560, as this is a policing and policing is not
>>> available in the outbound direction on 3560.
>>>
>>> --
>>> Marko Milivojevic - CCIE #18427
>>> Senior Technical Instructor - IPexpert
>>>
>>> FREE CCIE training: http://bit.ly/vLecture
>>>
>>> Mailto: markom_at_ipexpert.com
>>> Telephone: +1.810.326.1444
>>> Web: http://www.ipexpert.com/
>>>
>>> On Sat, Aug 6, 2011 at 13:19, gp <gs4me2me_at_gmail.com> wrote:
>>>>
>>>> Thank you Marko for explanation, it helps.
>>>>
>>>> What confusing me if I have a task to guaranteed some traffic for
>>>> example 10Mbps on giga interface on switch, and I cannot use priority queue,
>>>> so I want to send that traffic before packet in shared queue in way to put
>>>> it in shaped queue which will be served before shared queues.
>>>>
>>>> The problem is that I donb t know what type of interface will be
>>>> connected to my switch (1Gbps or 100M) and that is value from which will be
>>>> calculated value for shaping on particular queue.
>>>>
>>>> For example:
>>>> Negotiated speed = 1Gbps
>>>> Srr-queue bandwidth shape 0 100 0 0
>>>> Queue 2 will be shaped to 100Mbps
>>>>
>>>> Negotiated speed = 100Mbps
>>>> Srr-queue bandwidth shape 0 100 0 0
>>>> Queue 2 will be shaped to 10Mbps
>>>>
>>>> In other way as I understand there is no way to hard code shape value
>>>> regarding to negotiated speed?
>>>>
>>>> Regards,
>>>> Gp
>>>>
>>>>
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: Marko Milivojevic [mailto:markom_at_ipexpert.com]
>>>> Sent: Saturday, August 06, 2011 7:42 PM
>>>> To: gp
>>>> Cc: ccielab_at_groupstudy.com
>>>> Subject: Re: shape on 3560
>>>>
>>>> It will be using the bandwidth available to the SRR.
>>>>
>>>> Cat2#sh mls qos interface fa0/18 queueing
>>>> FastEthernet0/18
>>>> Egress Priority Queue : disabled
>>>> Shaped queue weights (absolute) :  25 0 0 0
>>>> Shared queue weights  :  25 25 25 25
>>>> The port bandwidth limit : 100  (Operational Bandwidth:100.0) <<<<<<<
>>>> The port is mapped to qset : 1
>>>>
>>>> See the "port bandwidth limit" line - that's the BW available to the
>>>> SRR. It is derived from the negotiated speed by default, but can be
>>>> limited using "srr-queue bandwidth limit" command on the interface.
>>>>
>>>> Now, let's see if configured bandwidth influences this in any way:
>>>>
>>>> interface FastEthernet0/18
>>>> bandwidth 50000
>>>> !
>>>>
>>>> Cat2(config-if)#do sh mls qos int fa0/18 qu
>>>> FastEthernet0/18
>>>> Egress Priority Queue : disabled
>>>> Shaped queue weights (absolute) :  25 0 0 0
>>>> Shared queue weights  :  25 25 25 25
>>>> The port bandwidth limit : 100  (Operational Bandwidth:100.0)
>>>> The port is mapped to qset : 1
>>>>
>>>> Doesn't look like it does. If I change the bandwidth limit.
>>>>
>>>> interface FastEthernet0/18
>>>> bandwidth 50000
>>>> srr-queue bandwidth limit 25
>>>> !
>>>>
>>>> Cat2(config-if)#do sh mls qos int fa0/18 qu
>>>> FastEthernet0/18
>>>> Egress Priority Queue : disabled
>>>> Shaped queue weights (absolute) :  25 0 0 0
>>>> Shared queue weights  :  25 25 25 25
>>>> The port bandwidth limit : 25  (Operational Bandwidth:27.28)
>>>> The port is mapped to qset : 1
>>>>
>>>> Whenever in doubt - ask IOS :-)
>>>>
>>>> --
>>>> Marko Milivojevic - CCIE #18427
>>>> Senior Technical Instructor - IPexpert
>>>>
>>>> FREE CCIE training: http://bit.ly/vLecture
>>>>
>>>> Mailto: markom_at_ipexpert.com
>>>> Telephone: +1.810.326.1444
>>>> Web: http://www.ipexpert.com/
>>>>
>>>> On Sat, Aug 6, 2011 at 01:18, gp <gs4me2me_at_gmail.com> wrote:
>>>>>
>>>>> Hello experts,
>>>>>
>>>>>
>>>>>
>>>>> When doing shaping on 3560 interface does reference bandwidth is
>>>>> configured
>>>>> bandwidth with bandwidth command or negotiated speed?
>>>>>
>>>>>
>>>>>
>>>>> For example the switch port is connected on Fast Ethernet router
>>>>> interface
>>>>> and I configured bandwidth 1000000 on switch port.
>>>>>
>>>>> With srr-queue bandwidth shape 0 100 0 0, will queue 2 be shaped on 10
>>>>> or 1
>>>>> Mbps?
>>>>>
>>>>>
>>>>>
>>>>> Thank you!
>>>>>
>>>>>
>>>>> Blogs and organic groups at http://www.ccie.net
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>
> --
> Carlos G Mendioroz  <tron_at_huapi.ba.ar>  LW7 EQI  Argentina
Blogs and organic groups at http://www.ccie.net