From: Alexei Monastyrnyi (alexeim@orcsoftware.com)
Date: Tue May 02 2006 - 04:34:23 ART
good points, right!
on 29/04/2006 09:06 Petr Lapukhov wrote:
> Actually, bandwidth configured at interface is used _directly_ to
> calculate MQC limits, along with "max-reserved-bandwidth".
>
> Some important things to remember with MQC (effective since 12.2):
>
> 1) By default, 25% of interface configured bandwidth is chomped
> from the available interface bandwidth [if_bw]. That is,
> "max-reserved-bandwidth" [res_bw_prc]=75%*
>
> 2) When you issue "bandwidth" [bw(i)] under a class [i], you set ABSOLUTE
> value.
> This value could NOT exceed [if_bw*res_bw_prc]. Available interface
> bandwidth
> is decremented accordingly, when you reserve bandwith for a class.
>
> Also, SUM of all bandwidths across all classes, could NOT exceed
> [if_bw*res_bw_prc]. That is: sum(bw(i))<=if_bw*res_bw_prc;
>
> 3) When you issue "bandwidth percent" [prc(i)] under class [i], you set
> ABSOLUTE value again, and it is measured from the [if_bw]. That is, you
> reserve
> [prc(i)*if_bw] for class "i". Available interface bandwidth is
> decremented
> accordingly to reservation.
>
> Again, [prc(i)*if_bw] could NOT exceed [if_bw*res_bw_prc]. The same rule
> holds for
> sum of percents [sum(prc(i))*if_bw<=[if_bw*res_bw_prc].
>
> That is, sum(prc(i))<=75% by default.
>
> 4) Now, for the "priority" and "priority percent". Those reserve bandwith
> for priority queue, and configure policer. Priority chomps available
> bandwidth
> from interface. Both variants of priority command works with [if_bw]
> and are
>
> ABSOLUTE.
>
> 5) Lastly, "bandwidth remaining percent". We already know that IOS
> demands it's tribute for 25% of [if_bw]. Next, we remember
> that there are priority classes under CBWFQ. They claim their
> bandwidth too: [pri_bw] = either sum(pri_bw(i)) or
> [if_bw*sum(pri_prc(i))]
> where [i] numbers priority classes.
>
> So after we configure "priority" classes, we have remaining bandwidth
> [total_rem_bw]=[if_bw*res_bw_prc]-[pri_bw].
>
> Finally, "bandwith remaining percent" divides the [total_rem_bw] in
> RELATIVE
> percent values. That is, [sum(rem_prc(i))<=100%], and remaining
> bandwidth
> reserved for a class "i" is:
>
> [rem_bw(i)] = [total_rem_bw]*[rem_prc(i)].
>
> 6) And last, but not least: you are forced to use consistent units for
> all
> classes (e.g. you could not mix "bandwidth percent" and "bandwidth
> remaining percent") for non-priority classes.
>
> HTH
> Petr
>
> 28.04.06, Alexei Monastyrnyi <alexeim@orcsoftware.com> NAPISAL(A):
>>
>> My understanding is it is relevant if you use "bandwidth percent" in
>> your MQC configuration or something similar referring to relative
>> bandwidth, being opposed to absolute values... But I might miss
>> something here.
>>
>> I.e. if you need to configure bandwidth 512K in your MQC task, no
>> technical need for "bandwith" on interface. Though in real life you'd
>> better keep it in sync with real bandwidth just to be as consistent as
>> possible with your OSPF or EIGHR domains etc
>>
>> A.
>>
>>
>> on 28/04/2006 12:19 Shamin wrote:
>> > Hi,
>> >
>> > First of all my thanks to all you guys for your great inputs.
>> >
>> > This is with reference to the IEWB LAB2 Ver3.0 Task 8.2
>> >
>> > It is mentioned in the solution guide as follows ..
>> >
>> > "Output queue calculations for the MQC are based on the configured
>> > bandwidth value of the interface and not the speed the interface is
>> > clocked at.Be sure to set the appropriate bandwidth value when
>> > configuring the MQC on an interface"
>> >
>> > As per this statement , what I understand is, when configuring MQC on
>> > any interface, it is necessary that we configure the bandwidth command
>> > on the main interface, even if it is not mentioned in the lab
>> > requirements.
>> >
>> > What confused me was that, for a similar task in LAB4 Ver3.0 Task 8.2,
>> > there was no bandwidth configured under the main interface.
>> >
>> > So i am bit confused here, My question will be, is it mandatory to
>> > configure the banwidth command on the main interface for MQC, even if
>> > it is not mentioned in the LAB requirements?
>> >
>> > Regards
>> > shamin
>> >
>> >
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