[e2e] Why do we need TCP flow control (rwnd)?

[Detlef Bosau]

Abraham Matta wrote:
>> isn't it up to the sending side to decide when 
>> to stop probing the network?
>>     
>
> I don't see a good reason for the sender *not* to stop probing the
> network if it is told *explicitly* by the receiver about the rate at
> which the sender should send?
>
> Ideally, if the network *explicitly* tells the sender about a (fair or
> not) rate at which the sender should send, then no probing by the sender
> is needed (similar to the good old ATM explicit rate control ;)  
>   
However: TCP does not probe for a "rate" but it probes for _storage_ 
capacity.
The "rate" is a result of selfclocking: A TCP sender is clocked / paced 
by ACK packets.

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