Date: Wed, 06 May 2009 11:10:45 -0400 From: "Kaegler, Mike" <KaeglerM@tessco.com>
I have a new T3 thats 65msec long. I'd usually be using iperf to test new links, but at 65msec, even at the maximum window size, I can only get 6-8mbit through. No combination of options I've been able to find has gotten me more than 6mbit through this link. Should I just shotgun 9 copies of it?
Are there better ways to test these links? Can one verify this link with just a pair of 7200s and linux machines on either side? Or is this something one really needs "real" test hardware for? If 6mbit go through clean, is there a real chance 44 will not?
What is "maximum window size"? For T3 at 65 ms (is that one-way or RTT?) you don't need a really big window. Sounds like the system may need tuning. See http://fasterdata.es.net/ I use iperf at multiple Gigabit speeds and it works on a tuned system. You might want to use UDP for testing. It does not care about RTT, but is less efficient to receive. At 45 Mbps, there should be no problems, though. If all else fails, run 4 or 5 iperf jobs in parallel. (Use a different port for each.) -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751