Re: TCP performance on a lossy 1Gbps link

From: Pieter Smit
Date: Fri Dec 11 2009 - 00:44:53 EST


I would suggest you look at the tcp congestion avoidance.

http://www.mjmwired.net/kernel/Documentation/networking/tcp.txt
The Westwood algorithm: Quote "Its authors claim that Westwood is
especially good for wireless links or other situations where the loss
of an occasional packet may have nothing to do with congestion. "

see
# cat /proc/sys/net/ipv4/tcp_available_congestion_control

Cheers,
Pieter E Smit

On Thu, Dec 10, 2009 at 11:46 PM, Randy Macleod <macleodr@xxxxxxxxxx> wrote:
>  Mathew,
>
> Matthew Hodgson wrote:
>> I've got a dedicated 1000Mbps link between two sites with a rtt of 7ms,
>> which seems to be dropping about 1 in 20000 packets (MTU of 1500 bytes).
>>  I've got identical boxes at either end of the link running 2.6.27
>> (e1000e 0.3.3.3-k6), and I've been trying to saturate the link with TCP
>> transfers in spite of the packet loss.
>
> Sorry for the late reply...
>
> If you just want to avoid the dramatic impact of dropped packets
> due to something in the network getting overloaded,
> you might consider:
> http://www.gridmpi.org/pspacer-1.0/README.en.html
>
> <quote>
> PSPacer achieves precise network bandwidth control and smoothing of
> bursty traffic without any special hardware.  It is implemented as a
> Linux loadable kernel module, i.e. a classful queuing discipline (Qdisc)
> module available for traffic control with tc (8) command.
>
> ...
> (2) PSPacer uses the IEEE 802.3x PAUSE frame as a gap between packets.
>
> </quote>
>
> Always seemed like a cool idea although I haven't tried it myself.
>
> Hope this isn't too late to help.
>
> // Randy
>
>
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