[e2e] TCP out-of Order

[Fred Baker]

At 03:07 AM 1/22/2002, kalyan uppalapati wrote:
>1) why TCP behaves so badly, when we use multipath network with a small 
>delay difference in one link ?? the throghput drops gradually.

In your simulations, it would be good to tag the various things that happen 
to cwnd in the sender, and analyze them.

Everything in TCP is conceptually handled in a certain order, and when 
there is one routing path, that order is mostly obeyed. The places where it 
is not obeyed generally result from losses, and cwnd is managed to minimize 
losses in these cases. However, when traffic from a single session is 
sprayed over multiple paths with varying delay, some of those events happen 
and are the result of differing routing. When cwnd is reduced to affect 
congestion and is in fact a result of something else, the result is as you 
describe.