[e2e] admission control vs congestion control

Detlef Bosau detlef.bosau at web.de
Fri Apr 21 09:20:40 PDT 2006

Fred Baker wrote:

> On Apr 17, 2006, at 6:18 PM, Detlef Bosau wrote:
>> Excuse me: What´s the very difference between these mechanisms and  
>> good ol´ TDM as it is used in line switched networks with excellent  
>> results for decacdes now?
> simple. TDM is not statistical; these are.
> In other words, if you allocate mumble percent of a link for video,  
> and have several video streams using the capacity, in a TDM world the  
> bits arrive in an orderly fashion and get clocked out the other side.  
> The only "congestion" is that you might use up the capacity you have  
> allocated. In the Internet, each video stream might, under certain  
> circumstances, have the first packet of its frame arrive  
> simultaneously, building up a queue. 

O.k., this is the particular story with speech compression etc.

There _are_ scenarios where this approach makes sense (and is thus 
conducted for some years now.)
In addition, media streams will typically remain quite time sensitive 
and you will have to provide appropriate switching mechanims.

What I´ve seen als "multimedia over the Internet" so far is not 
convincing. And this is not surprising as I do not see a real chance to 
have multimedia work in a best effort network.

You talk about decent video.

Is this "decent"? You surely don´t talk about these funny webcam 
pictures and this stuff. This is not "decent". This is ridiculous.
There was a certain multimedia over IP hype in the 90s.

Thank´s god, it´s over now.


Detlef Bosau
Galileistrasse 30
70565 Stuttgart
Mail: detlef.bosau at web.de
Web: http://www.detlef-bosau.de
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