BRL, and ported to AIX by Prof. Peter Haas, University of Stuttgart). tsock is a program that uses the UltraNet socket emulation library to perform numerous network exercises, among them to measure the pure network performance by eliminating any hard disk or processor load influence on the data transfer rate by sending data packets directly from memory to memory. We selected to send bursts of packets ranging from 1 byte to 50 kilobytes, as this might be a more realistic approach than just shifting large files around. In this scenario an average data transfer rate of about 12 MB/s was achieved which corresponds to the theoretical maximum data transfer rate of an FDDI connection (12.5 MB/s=100 Mb/s).
2.We used ftp to conduct several file transfers of a 300 MB file from different nodes in SP2. We sent this file to /dev/null on node 10 in SP21, to eliminate any hard disk influence on the receiver side:
root@sp2n09:/ ftp 10.2.1.1 Connected to 10.2.1.1.
220 sp21n10 FTP server (Version 4.1 Tue Mar 17 14:00:13 CST 1998) ready. Name (10.2.1.1:root):
331 Password required for root. Password:
230 User root logged in.
ftp> put bos.obj.ssp.itso /dev/null 200 PORT command successful.
150 Opening data connection for /dev/null.
226 Transfer complete.
299878400 bytes sent in 65.95 seconds (4441 Kbytes/s) local: bos.obj.ssp.itso remote: /dev/null
ftp> quit
221Goodbye.
root@sp2n09:/space
As can be seen in the screen shot, the slow internal SCSI disks of the nodes in SP2 would not allow the transfer rate to exceed 4.5 MB/s. So we decided to start four ftp programs on four different nodes in SP2. We expected these four file transfers to sum up to an aggregate throughput of about 18 MB/s over the net. This would be beyond the throughput of an FDDI adapter, so we expected to reach the limits of the FDDI adapter, either in the GRF or on node 10 in SP21.
With this scenario, we measured an average transfer rate of about
