Date: Tue, 11 Dec 2007 09:21:17 +0400 From: rihad <rihad@mail.ru> To: Stephen.Clark@seclark.us Cc: Luigi Rizzo <rizzo@icir.org>, freebsd-net@freebsd.org Subject: Re: Pipe queues Message-ID: <475E1E4D.4090409@mail.ru> In-Reply-To: <475DA624.4010104@seclark.us> References: <475D6FD7.2000500@mail.ru> <DCFF3417-FC01-4F2C-ACA5-03CC0881DE59@mac.com> <20071210120353.B40679@xorpc.icir.org> <475DA624.4010104@seclark.us>
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Stephen Clark wrote: > Luigi Rizzo wrote: > >> On Mon, Dec 10, 2007 at 11:22:33AM -0800, Chuck Swiger wrote: >> >> >>> On Dec 10, 2007, at 8:56 AM, rihad wrote: >>> >>>> Hi, >>>> >>>> I'm having a hard time to understand what pipe queues are with >>>> respect to bandwidth limitation. ipfw(8) and dummynet(4) manuals >>>> didn't help me much. >>>> >>> Pipes and queues are two different things; a pipe simulates a >>> network link, and a queue is used to hold packets which are >>> backlogged because they are arriving faster than the outbound link >>> (ie, a pipe) can transmit them. >>> >>> >>>> How does dummynet's traffic shaping function? >>>> >>> It uses a variant of weighted fair queuing. >>> >> >> actually the shaping uses a leaky bucket algorithm. >> The weighted fair queuing is the queue management scheme used >> when you have multiple queues attached to the same pipe >> >> cheers >> luigi >> _______________________________________________ >> freebsd-net@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-net >> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >> >> >> > Pipes are used to limit bandwidth. Queues are used to assign priority to > different classes of traffic. As an example > suppose you wanted to limit bandwidth for a specific ip to 2mbs. You set > up a pipe to do this and use ipfw to put traffic > from this ip into the 2 mbs pipe. If you then wanted to prioritize ftp > traffic at higher than priority than all other traffic for > this same user you would create 2 queues to feed the 2mbs pipe. You > would send the ftp traffic into the higher priority queue > and all other traffic for this user into the other queue. > And if I _only_ want to shape IP traffic to given speed, without prioritizing anything, do I still need queues? This was the whole point.
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