From: Carlos G Mendioroz (tron@huapi.ba.ar)
Date: Thu Jun 26 2003 - 07:44:25 GMT-3
Actually, with the 1K:1K:1K:1K assignment, looking the flow of one of
the 1k packet size class, the flow would be:
1 packet - 6 packet time gap - 1p - 2 ptg - 1p - 2ptg - 1p - 2ptg
whereas in the 4K:4K:4K:4K, it would be:
4 p - 12 ptg.
It seems to me that the second is bumpier than the first...
Howard C. Berkowitz wrote:
> At 8:11 PM -0300 6/25/03, Carlos G Mendioroz wrote:
>
>> Howard,
>> I don't see how what you say can happen.
>> Would it be possible for you to come up with a simple example where a
>> ratio assignment would generate high short term throughput variability,
>> and a good matching with one calculated by normalize/divide/multiply
>> stuff ?
>
>
> Four classes, each to receive 25%.
>
> Let's say that one of the classes is an old IBM Token Ring application
> that still uses the 4K packet size. For ease in computation, let the
> average packet size of the other queues be 1K.
>
> If you set up the classes 1K:1K:1K:1K, the IBM queue will be serviced
> only every 4th cycle.
>
> If you set it up 4K:4K:4K:4K, and there is enough traffic to fill each
> cycle, the traffic flow will be smooth (1 packet:4 packets:4 packets: 4
> packets).
>
>>
>> Using big numbers may do, but using ratios it would be easier to
>> actually use smaller numbers anyway.
>>
>> Thank you,
>> -Carlos
>>
>> Howard C. Berkowitz wrote:
>>
>>> At 4:02 PM -0500 6/25/03, John Humphrey wrote:
>>>
>>> Well, yes, but there are warnings involved. Yes, it's true that
>>> remembering the deficit will make the long-term statistical
>>> allocation of bandwidth more accurate with less effort.
>>>
>>> The problem, however, is that if you'v not estimated well (i.e., used
>>> estimates that reasonably reflect the average packet size), you will
>>> get short term peaks and valleys in the throughput per class. That
>>> may be OK for non-interactive traffic, but bad for interactive and
>>> catastrophic for real-time.
>>
>
>
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-- Carlos G Mendioroz <tron@huapi.ba.ar> LW7 EQI Argentina
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