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Subjectslow FTP (etc) transfers.
AFAICT, my strange slow transfers across ppp/etc links at least are caused
not by the PPP driver, not by serial overruns, but by Linux tcp/networking.

My setup -

33.6 modem 24hr Internet connection to Cisco 2511 (10.3(7))
Debian Linux
kernel 1.3.79
PPP 2.2.0e

I have a LAN here, with a Win95 box on the other end of my crossover
cable. It is also on the 'net.

Remote host, just to the other side of the router, is an IRIX 5.3 IP22 (I
would have used the Solaris box, but that would have driven the transfer
even lower, what with the Solaris-Linux badness goin' on right now.)

File is an avi that I compressed with gzip -9, about a meg and a half in
the end.

Ftp transfer on the Windoze box (using their commandline ftp prog) - 3.13,
3.13, and 3.1 k/s.

Ftp transfer on my box, using debian commandline ftp - 2.6, 2.5 k/s.
ncftp - 2.45 k/s.

This is a beautiful demonstration of the flaw, since for the Win95 box the
packets are flowing right through Linux's network stack, and it's not
seeing the same crappy performance as for Linux. This, for me at least,
eliminates the serial port or the PPP connection or the remote system or
any other stuff. It's just TCP badness, what looks like periodic
pause-retransmit's (I lurrrve external modems).

If I'm really bored tonight I'll do some backtracking and locate the code
chunk that does it. Whee.

--
Ryan Smith-Roberts - rsr@citadel.fine.net | Linux - anything else
http://citadel.fine.net/ finger/www 4 PGP | Would be uncivilized!

Yow! Thousands of years of ancient Chinese wisdom finally pays off!



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