No worries. Why does it work? Every packet leaving an interface is up to MTU bytes in length. Let's say that a byte is ten bits (8+ 1start+1stop). So a 1500byte packet is 15000 bits. On a 28.8K connection, that means a 1500 byte packet takes 0.52 seconds to transmit. Assuming that the queueing discipline is FIFO (first-in-first out) and the queue length on the interface is, say, 10 packets, a packet can take 10*0.52 seconds to get to the head of the queue. Plus transmission time, that's 5.2 (for queuing) +0.52 for transmission. Quite a delay. You may be able to do better by shortening the packet queue on the interface (ip link set ppp0 qlen 4) for example. Or attaching an SFQ queueing discipline (tc qdisc add dev ppp0 root handle 1: sfq perturb 10) - although for SFQ, I think you'd want a more substantive queue length. On Tue, 2003-09-09 at 18:52, Daniel Horth wrote: > wow - from 8 second ping responses on my heavily loaded link to 2 second > just by changing the MTU - sure I'll be able to improve further on that with > experimentation. > > thanks for that! > > - dan. > > > -----Original Message----- > From: Dancer Vesperman [mailto:dancer@xxxxxxxxxxxxxxxxxxxxx] > Sent: Tuesday, 9 September 2003 6:37 PM > To: Daniel Horth > Subject: Re: newbie - shaping a PSTN connection > > > I'd seriously advise cutting your MTU/MRU down. A lot. Say as low as 562 > or 168. If your MTU/MRU is defaulting to 1500, it's going to be hard to > get any effective shaping on your link. > > On Tue, 2003-09-09 at 18:21, Daniel Horth wrote: > > Hi - I've been going through the LARTC how-to and have successfully used > the > > sample scripts (and wondershaper) with my xDSL links. > > __________________________________ > Euroluce Lighting Australia PTY LTD > 92-94 Tennyson Road, Mortlake, NSW 2137 > Ph: (02) 9743 6099 Fx: (02) 9743 6406 > http://www.euroluce.com.au/ > > The contents of this email are confidential. If you are not, or believe you > may not be, the intended recipient of this email, please let us know by > reply and then delete it from your system. You should not copy the message > or disclose its contents to anyone. No warranty or other assurance is given > by us that this email is free of any virus or any other defect or error. > > Any views or opinions presented in this email are solely those of the author > and do not necessarily represent those of the company. If verification is > required please request a hard-copy version. > > Scanned by Inflex - Queries to: postmaster@xxxxxxxxxxxxxxx -- _______________________________________________ LARTC mailing list / LARTC@xxxxxxxxxxxxxxx http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
