[e2e] Some thoughts on WLAN etc., was: Re: RES: Why Buffering?

[David P. Reed]

A quick answer:

On 07/06/2009 11:21 AM, rick jones wrote:
>
> Why is TCP's waiting too long in some ways right, but 802.11's waiting 
> too long relatively useless?  Both seem to be letting those above them 
> have time to make their own decisions?
>
TCP's waiting too long doesn't hide degradation of the end-to-end 
channel from the app, *because the app can close the circuit, which 
halts any further retransmission*.

802.11's trying at the link layer for too long has no way for the higher 
layer to tell it to stop trying.

If the higher layer can change the lower layer's behavior based on its 
requirements, that's an improvement.

But please, please, please don't mistake this observation for a claim 
that either TCP or 802.11 are designed to take into account the variable 
needs of end-to-end apps for semantics other than maximal-throughput FTP 
- that's one reason I fought for UDP (along with the others who did as 
well), which exposes raw IP through a host-mux/demux interface based on 
ports.