Re: Very poor PPP interface performance
Re: Very poor PPP interface performance
- Subject: Re: Very poor PPP interface performance
- From: Jean-Edouard BABIN <email@hidden>
- Date: Tue, 26 Oct 2004 22:52:59 +0200
Hello
You're right, i also already setup a ppp tunnel over ssh
With something like
pppd pty 'ssh -x -t -e none user@server /usr/sbin/pppd passive noauth 9600'
noauth 10.0.0.1:10.0.0.2
and get the same poor performance, and bad ping also :/
on 26/10/04 20:55, « Jamie Wood » <email@hidden> wrote:
> I have noticed that the performance of the PPP interface in Mac OS X 10.3.5
> is not very good at all. I have written a simple program that brings up a
> PPP interface, configures it using "ifconfig", and reads incoming packets.
> If I use another program to repeatedly send UDP packets to my newly-created
> PPP interface in a tight loop, the sendto() function quickly begins to
> return a "No buffer space available" error. The program which is reading
> packets from the PPP interface only reports that about 1% of the packets
> even get through.
>
> If I run a similar set of tests on Linux, none of the UDP packets are
> dropped, and sendto returns no errors.
>
> In another test, I tried using iperf to measure the throughput of a ssh-pppd
> tunnel. The most I can get without compression enabled is 1.2 Mbits/sec over
> a 10 Mbit link. The same test on Linux results in numbers which are close to
> link speed (one of our tests resulted in ~28 Mbits/sec).
>
> One interesting thing I and my collegues have observed is that if a Linux
> box is used for one end of the ssh-pppd tunnel, we get about 7 Mbits/sec
> download speed (Linux->Mac OS X) but only about 800 Kbits/sec upload speed
> (Mac OS X->Linux).
>
> All of this seems to indicate that there is some sort of performance problem
> between the TCP stack and the PPP interface code, which is causing some sort
> of serious delay when the interface picks up events from the stack.
>
> Any information about this behavior, and suggestions for possible
> workarounds/fixes would be greatly appreciated.
>
> Thanks,
> Jamie Wood
--
Jean-Edouard BABIN
Mail: email@hidden
Web : www.Jeb.com.fr
IRC : Jeb @ Undernet
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