[e2e] Delivery Times .... was Re: Bandwidth, was: Re: Free Internet & IPv6

Detlef Bosau detlef.bosau at web.de
Thu Dec 27 07:48:14 PST 2012

Am 27.12.2012 10:05, schrieb Detlef Bosau:
> E.g. in GPRS, the standard defines certain quantiles. E.g. for 1024 
> bytes, we have certain delay classes:
>                   mean                   0.95 quantil
> 1.:             < 2s                    < 7
> 2.:		< 15s			< 75s	
> 3.: 		< 75s			< 375s
> I don't now whether "mean" refers to "average value" or "median".

Of course, there are reaons for these high latencies: As David noted, 
these may result from a huge number of retransmissions.
And the difference between "mean" and the 0.95 quantil indicate a high 
variance, thus an application which will exploit the available 
"throughput", i.e. the "mean" latency, may require huge buffers - and 
thus see huge round trip times.

Hence, the question is whether TCP as is and mobile networks are really 

Obviously, it's a matter of fact that there is that TCP over mobile 
networks is requested from the market. So the issue is to find a good 
match, at least compromise, between expectation and reality here.

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