[e2e] Agility of RTO Estimates, stability, vulneratibilites

[Detlef Bosau]

Sireen Habib Malik wrote:
> 
> 
>> ..... something that exists *only* in the minds of professors of 
>> computer science, because they created it as a modeling tool.   The 
>> "network" we actually use is quite different.
> 
> 
> 
> What "network" should one consider when estimating RTO's (as given in 
> the topic)?
> 
> 

No one =8-)

My basic intention behind my original post was _not_ to understand the 
network between sender and receiver. Frankly spoken, I´m not quite sure 
whether this discussion will ever come to an end, particularly as more 
and more complexity is added to the Internet every day.

The focus of my question is thus not the network. It´s the RTO estimator 
itself.

I don´t want to replace it. It´s simple, it works.

I even don´t want to adapt TCP to more and more complex network 
structures. Why should I?

Perhaps one of he best characterisations of the situation may be found 
here, even for non german readers:

http://portale.web.de/Schlagzeilen/BilddesTages/msg/5911184/5911185/1/

As you see:
1.: Even pigs are not always RFC compliant, so why networks should be?
2.: Unfortunately, I´ve lost the link to the famous NS2 pig. Surely you 
remember it. It´s obvious: Simulators and models are an _abstraction_ of 
reality and there are notable differences.

My intention is to have a "top down" perspective to the network: What 
does TCP expect from a network? In other words: How must a network 
behave to make TCP work fine? How must a network _appear_?

Of course, when we talk about TCP, we talk about some transport system 
which conveys TCP datarams from here to there - one way or another, not 
nessecarily exclusive.

And even that is not true. I talk about TCP senders. So, TCP senders 
send TCP datagrams. In most cases, they honestly believe, there may be a 
TCP receiver at the other end of the line. Even _that_ is not granted.
Think of a mobile receiver. For years I had to deal with a project where 
streaming media should be conveyed to mobile receivers via IP!!!!!!
People wasted lots of mony to convey speach to a mobile receiver via 
VoIP, instead of using the obvious solution: the "speach service", which 
is offered by _every_ wide area mobile network technology on the market.

If I think of TCP, i may think of file transfer. When there is a simply 
yet perfect file transfer protocol in ISDN (let me take this example 
because there _IS_ one), why shouldn´t I use it if appropriate?

When you consider my Path Tail Emulation proposoal: The idea is to 
_hide_ networks behind "TCP conforming ones". So, it´s not my question 
what a network does offer. It´s the question what TCP requires. And then
the idea is to make a network _appear_ to conform to TCP requirements.

Basically, I think of mobile netowrks here. But I´m not restricted to 
mobile networks.

The question is: What is the ideal behaviour for a network used for TCP?

When I can answer this one, I want to make an arbitrary network to 
appear that way.

Detlef
-- 
Detlef Bosau
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