Date: Thu, 28 Jul 2005 21:32:21 -0400 From: Chuck Swiger <cswiger@mac.com> To: Daniel O'Connor <doconnor@gsoft.com.au> Cc: freebsd-net@freebsd.org, julian@elischer.org Subject: Re: AltQ + ng_iface Message-ID: <42E98725.1020600@mac.com> In-Reply-To: <200507291035.46770.doconnor@gsoft.com.au> References: <200507290834.10268.doconnor@gsoft.com.au> <42E97AF1.9060104@elischer.org> <200507291035.46770.doconnor@gsoft.com.au>
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Daniel O'Connor wrote: > On Friday 29 July 2005 10:10, Julian Elischer wrote: [ ... ] >>ipfw and dummynet work on ng_iface I believe. > > Well yeah, but dummynet is a little inflexible and can't prioritise ACKs (for > example) Either the "established" or the "tcpflags !syn,ack" keywords in a rule adding matching packets to a high-priority queue ought to do it...? Or perhaps you meant something more specific than just "TCP packets with TH_ACK" set? :-) Anyway, I'm not convinced that trying to classify packets within an established TCP connection in order to place them on different queues is a really good idea, since you're quite likely to reorder the packets by doing so. I'd expect both latency and bandwidth of a TCP connection to suffer very noticably if more than 10% or so of the packets arrive out of order... [ Hmm. I suppose that one could make an exception to the above generalization if URG was set, but the TCP stack already makes an effort to prioritize and deliver out-of-band urgent stuff as quickly as possible, anyway, right? ] -- -Chuck
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