[e2e] TCP losses
craig at aland.bbn.com
Mon Feb 28 05:30:10 PST 2005
In message <4222EA41.2020201 at tuhh.de>, Sireen Habib Malik writes:
>Having said that it is also clear that considering the protocol without
>considering the under-lying layers is not correct. Considering
>"congestion" alone as cause of losses is not sufficient - the protocol
>when zipping through layers underneath it, sees all kinds of failures.
>Those failures which cause the TCP to have "serious" performance problems.
>Obviously one way to correct those failures is at their respective
>layers. The other is to make TCP responsible for the 2*E2E loop for
>both the data transport and fault-recovery functionality.
Take a peek at Rainer Ludwig's doctoral dissertation on cross-layer
interactions in wireless. It is a useful discussion and starting point.
A useful observation is that, in certain situations, link layer retransmission
is just the right thing to help TCP, but in high loss scenarios it can
be wrong as TCP will retransmit and then you'll have the wireless layer
ardently trying to retransmit two copies of the same segment...
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