[e2e] RES: Why Buffering?

S. Keshav keshav at uwaterloo.ca
Fri Jun 26 12:37:02 PDT 2009

On Jun 26, 2009, at 3:16 PM, Lachlan Andrew wrote:

> No buffer is big enough to stop a long TCP(Reno) flow losing packets,
> because it will increase its window until it does.

I agree. What I meant to say was this: ideally, each source chooses a  
static window such that the sum of these window sizes is the BDP. In  
this case, the link is fully used and there is no queueing. Of course,  
the sources don't know these values, so they are forced to increase  
the window to probe the available capacity, which pushes the buffers  
towards fullness and the packets towards loss. In this situation,  
having large buffers is no help at all - it only delays the inevitable  
at the cost of increased delay to all.

All I was trying to do was to explain, as I knew best, the thought  
process that leads to the one-BDP-buffer rule of thumb


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