[e2e] Some thoughts on WLAN etc., was: Re: RES: Why Buffering?
David P. Reed
dpreed at reed.com
Mon Jul 6 09:12:58 PDT 2009
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
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