🚀 go-pugleaf

FTPing large files between institutes (each of them connected to the 
universities backbone net through a IGS) I get up to 1MB/s depending on 
the sending and receiving machines.

While the receive buffers of 386s and Sun SLCs are easily overrun when 
receiving more than a few packets, resulting in transfer speeds 
of 10KB/s to 200KB/s, modern workstations (eg. DEC 5000/200, Sparc 2) 
are well capable of sending and receiving Megabytes at 1MB/s.

My measurements were done between Suns and DECs local and over 
two IGS routers. The test file was about 4MB long.
It was 'preloaded' into the buffer cache and then sent into '/dev/null'.
Speeds between machines on the same cable or connected through 
2 CISCOs always came out at about 1MB/s without much difference.
Seems, the CISCO boxes are *really* fast.

A way to 'benchmark' the TCP overhead is to ftp a long file from the 
buffer cache into '/dev/null' through the 'local loopback' (127.0.0.1).
Then the local system has to send and receive the data at the same time,
doubling the overhead. Values seen on fast 386s are in the range 
of 200KB/s, while the Sun2 or DEC 5000/200 go well beyond 1MB/s.

You probably can't get more than *twice* the performance measured 
this way with any network controller on your system.

Stefan
-- 
 Stefan Esser,  Institute of Nuclear Physics,  University of Cologne,  Germany
 se@IKP.Uni-Koeln.DE                                           [134.95.192.50]