bridge query

[Peter Jeremy]

On 2007-May-08 14:20:27 +0500, suvashrestha at wlink.com.np wrote:
>i am using freebox 5.4 as a bridge using dummynet.
...
>When I add delay of 250ms and plr of 0.05 (5%), the packet transfer falls
>to 80Kbit/s.

How are you measuring packet transfer (single TCP socket, multiple TCP
sockets or UDP) and what were you expecting?

For a TCP connection, the window size needs to be able to handle at
least 1 RTT (0.5 second in this case) of data.  This translates to a
total of 5Mb (~640KB) outstanding data to get 10Mbps throughput.  With
only a single cnnection, you would need a 640KB window size - which is
far larger (an order of magnitude or so) than typical.

TCP is also designed to work on a mostly lossless link.  I am not sure
how much a 5% packet loss will affect it but I would expect it to be
significant.  I'm not sure how to optimise throughput in this
situation.

-- 
Peter Jeremy
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