nanog mailing list archives

Re: Testing LFNs


From: David Andersen <dga () cs cmu edu>
Date: Wed, 6 May 2009 11:17:09 -0400

set your system send and receive TCP buffers larger. You're probably being limited by that. With linux, make sure you have window auto- scaling enabled and have increased the maximum size it can grow to to at least 4MB.

Or test with UDP and blast as fast as you can so that you're not seeing TCP weirdness.

IOS includes a 'ttcp' command you can use on the router itself:

http://www.cisco.com/en/US/tech/tk801/tk36/technologies_tech_note09186a0080094694.shtml

  -Dave

On May 6, 2009, at 11:10 AM, Kaegler, Mike wrote:

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?

TIA,
-mKaegler


--
Michael Kaegler, TESSCO Technologies: Engineering, 410 229 1295
Your wireless success, nothing less. http://www.tessco.com/




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