>From: Luigi Rizzo [mailto:[EMAIL PROTECTED] > >On Wed, Jan 24, 2007 at 06:10:21PM +1100, Peter Jeremy wrote: >> On Tue, 2007-Jan-23 14:22:54 -0500, Andresen, Jason R. wrote: >> >I have a project that requires me to simulate a link with >varying but >> >well defined delay. The link is guarenteed to deliver packets in >> >order, so I wish to maintain that behavior with Dummynet. >> >> I don't think dummynet can do this in its current form. Based on > >actually dummynet never does reordering within a single pipe, even >if you change the delay on the fly. > >But this said, you should explain "varying but well defined delay", >because if you use TCP or similar as the source, then you >have no control on when the userland write->tcp transmission delay >anyways so the concept is a bit vague and probably not a meaningful >experiment. And even in any common network (from switched >ethernet to wireless to dsl...) you have some variance on the delay, >ranging from a fraction of a millisecond to much larger values, >due to queueing and/or protocol issues (e.g. MAC channel allocation) >and/or switch/router/operating system issues.
I'm trying to simulate a satellite link that has a normal delay of 1 second, but every 20-30 seconds or so the delay shoots up to 3.5 seconds for about 4 seconds and then settles back down to 1 second. >From what you said, I'm thinking that just twiddling the pipe on the fly will probably work. _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "[EMAIL PROTECTED]"
