Re: Reg: Quality of Service routing

[Parag M Panse <[e-mail]>]

On Mon, 21 Dec 1998, Masilamany Raguparan wrote:

> Raghu,
> 
> | Do we need QoS routing if we have enough infinite (I mean 
> | large ) bandwidth. 
> | 
> | >From my poor knowledge:
> | 
> | We need QoS routing b'cos we have limited BW and we want 
> | to give priority to QoS flows. If some one comes with 
> | a Tx system which supports 100s Gb/s,(say 128 channel WDM system)
> | Do we need to support the "special"  status for the QoS flows. 
> 
> Nature of the traffic can be very bursty and suck up your 100s of Gb/s
> bandwidth easily at any given time slot. Therefore, having just large bit
> pipes does not solve the QoS problem. 
> 
> Your delay = propagation time + queuing time + processing time equation
> certainly works, if you have enough capacity left on the link at the time
> of your request.

An implicit assumption that seems to be made here is regarding 'number of
data sources'. 

While designing a system that guarantees certain values of BW and 
end-2-end delay, given the present Internet model no  assumption can be 
made about the number of users or the number of sources geneating data.
Since no upper bound can be placed on the value of this parameter, even
though links with 100Gbps (or higher) , faster CPUs and faster memories
are given eventually the 'number of users' will always catch up and so
the "queueing delay" factor mentioned in the above equation for delay can
be never be eliminated. In fact as the number of users grow, the factor
will become more dominant. So it would be incorrect to say that delay ~
propagation time. 


> 
> Ragu.
> 

Regards...

-Parag