Hi, I am testing different ethernet switches regarding their ethernet frame dropping behaviour using iperf UDP mode (unicast and multicast). To do this I wanted to establish a baseline between the test PCs to make sure the sent packets do not get lost at the PCs, ie all losses are the switches problem. I am using iperf 2.0.4. I tested the iperf UDP setup using a crossover ethernet cable to connect the test PCs.
Problem #1: iperf is not sending at the specified speed I specify "-b 100M" at the UDP client, but according to the client's reports I only get between 70..80Mbit/s. I can increase the "-b"-parameter to "200", which then gets me a higher reported throughput, but then also the UDP packet loss increases. Problem #2: iperf is loosing packets even with test PCs directly connected Using "-b 80M" or higher, I always get lost packets. The number of lost packets varies with the specified bandwidth setting "-b"; ie more requested bandwidth produces more lost packets. I have shutdown all(most) unnecessary services (like X11, SSHd, NFS etc) and ran iperf from console. The PCs are not new (from Celeron III/400MHz to Celeron M/1GHz) or low power (Intel Atom), the NICs are either Intel (e100) / Realtek (8139too) Fast Ethernet. All PCs are running current Linux kernels (2.6.27.x) and Ubuntu or openSuSE 11.1 installations. I was reading through the threads "Iperf Transmit leading to 100% CPU Utilization" and wondered if this problem, together with my rather low power hardware could be the cause of my above problems #1 and #2. The thread talks about patches to apply to iperf to improve the UDP mode, but I could neither find the patch itself or if it is applied to the iperf trunk source. Any help or comment on how to get rid or circumvent the above mentioned problems is appreciated. Regards, Thomi ------------------------------------------------------------------------------ This SF.net email is sponsored by: High Quality Requirements in a Collaborative Environment. Download a free trial of Rational Requirements Composer Now! http://p.sf.net/sfu/www-ibm-com _______________________________________________ Iperf-users mailing list Iperf-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/iperf-users
