FTP/HTTP transfer rate slows down w/ time through LINUX BOX & IP Masquerading...

FTP/HTTP transfer rate slows down w/ time through LINUX BOX & IP Masquerading...

Post by The Applema » Wed, 20 May 1998 04:00:00



Here is my Linux box:
486SX/33 w/ 8meg RAM
16 meg SWAP
Global Village 56kx2 external modem (ISP only supports 33.6k though...)

I have set up IP masquerading, X-windows, telnet, ftp, etc from my
Windows95 box to the Linux box.  I have diald up and running as well.  I
can run Netscape, ftp, ping, telnet, nntp, etc directly from my Windows95
box and it will run through the Linux box (forcing a dial-up if not already
connected).  It seems to run great except...

Just yesterday I was downloading a rather large file (2.5meg) and I wanted
to keep my main phone line open (for browsing the net, etc) so I decided I
would telnet to my Linux box and have it ftp the file I wanted on the other
line.  Well everything worked great except it seemed to be taking too long.
 At first I noticed the modem RX/TX lights were constantly on, but over
time they would light up less frequently.  Eventually they would only blink
once every 30 seconds or so.  I checked the file size and it wasn't
increasing very quickly.  

Does this have something to do with the computer hardware?  
Does it have something to do with the way Linux multitasks?
Does the transfer rate not dynamical change for Linux?  (e.i. If ftp and
http running and you stop http - will the ftp bandwidth increase to make
use of the new bandwidth resources released by stopping http?)

I'm thinking that Linux will decrease the transfer rate but not increase it
back up if more bandwidth becomes available.  Or perhaps if I do something
else with the machine that requires more memory/CPU time, it will not give
it back to the ftp session once I am done?  I really don't know how this
works, but I wasn't doing anything major on the Linux box during the
transfer.  I was telneted into it from another session just so I could
check the progress of the file transfer by doing a "ls -l" in the download
directory, but that's it.  What gives??

I notice the same thing happening when using Netscape on my window95 box
through the linux box w/ IP masquerading.  What's the deal?

Henry

 
 
 

FTP/HTTP transfer rate slows down w/ time through LINUX BOX & IP Masquerading...

Post by The Applema » Thu, 21 May 1998 04:00:00


Here is my Linux box:
486SX/33 w/ 8meg RAM
16 meg SWAP
Global Village 56kx2 external modem (ISP only supports 33.6k though...)

I have set up IP masquerading, X-windows, telnet, ftp, etc from my
Windows95 box to the Linux box.  I have diald up and running as well.  I
can run Netscape, ftp, ping, telnet, nntp, etc directly from my Windows95
box and it will run through the Linux box (forcing a dial-up if not already
connected).  It seems to run great except...

Just yesterday I was downloading a rather large file (2.5meg) and I wanted
to keep my main phone line open (for browsing the net, etc) so I decided I
would telnet to my Linux box and have it ftp the file I wanted on the other
line.  Well everything worked great except it seemed to be taking too long.
 At first I noticed the modem RX/TX lights were constantly on, but over
time they would light up less frequently.  Eventually they would only blink
once every 30 seconds or so.  I checked the file size and it wasn't
increasing very quickly.  

Does this have something to do with the computer hardware?  
Does it have something to do with the way Linux multitasks?
Does the transfer rate not dynamical change for Linux?  (e.i. If ftp and
http running and you stop http - will the ftp bandwidth increase to make
use of the new bandwidth resources released by stopping http?)

I'm thinking that Linux will decrease the transfer rate but not increase it
back up if more bandwidth becomes available.  Or perhaps if I do something
else with the machine that requires more memory/CPU time, it will not give
it back to the ftp session once I am done?  I really don't know how this
works, but I wasn't doing anything major on the Linux box during the
transfer.  I was telneted into it from another session just so I could
check the progress of the file transfer by doing a "ls -l" in the download
directory, but that's it.  What gives??

I notice the same thing happening when using Netscape on my window95 box
through the linux box w/ IP masquerading.  What's the deal?

Henry

 
 
 

1. Problem: FTP & SMTP transfers of large files slow down and die

Hi!

This is my setup:

 - Company 100 MBits network
 - a Win2k box
 - a Suse Linux 8.0 notebook with 3Com megahertz PCMCIA eth
 - Sendmail runnning as deamon/smtp serv (couldn't figure out the
version, sorry)
 - vsftpd
 - firewall is turned off

This is what happens:

 ftp:
    initiate file transfer, everything goes fine for the first couple
of   minutes until the transfer rate drops to about 52 kb/s (could be
even lower, but this is what the client says (WS_FTP)) and so would
take about 37000 gazillion hours to tranfer a 1 gig file. This always
happens... (note: i use the same client to connect to an aix ftpd on
the same network and all works fine)

 smtp:
     when trying to upload larger files (>1mb) same thing happens:
initially
the transfer rate is ok but then all the sudden drops to near zero
(both my client and iptraf on the notebook confirm that)
When connecting to other smtp servers on the net, everything goes of
without a hitch though, even transfers of 1gig files. After about 30
minutes idling the console log shows a "sendmail: syserr: collect: i/o
error on ..." message ... then my client, completely unrelated
(timewise), will shut down saying: socket error.

The above also happend when I had 7.2 installed, although sometimes a
tranfer would even go through.

Related note: I work via telnet from the linux box to an aix the whole
day and nothing ever happens (meaning, it works fine) plus I repeately
used "bing" and "ping" to check for dropped packages and collisions,
nothing, unfortunatly.

Any hint would be greatly appreciated :)

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