On Tuesday 22 June 2004 06:00, Ed Wildgoose wrote: > >I'm running PPPoEoATM here. I don't know what my actual PPPoE overhead > > is, but I guess 10 bytes is reasonably close enough. PPPoE is handled by > > my Westell Wirespeed, which doesn't provide any useful cell information. > > At the moment I cannot easily obtain a cell count to determine my actual > > PPP overhead. > > Try bumping the protocol_overhead up to 16 for PPPoE (from 10). You > should also make sure that your MTU is lower than that required by your > PPPoE provider or else you will get ethernet packet fragmentation and I > doubt we want to extend the patch to cover those situations anyway. The largest MTU I could use is 1492. I have the Westell Wirespeed handling PPPoE, so I speak through eth0 locally. Until recently that was fine, but now I need to use 1492 instead of 1500 on eth0 due to strange SSH hangs that haven't happened in a year at 1500 with the same configuration. It's odd. All other machines are using 1500 without incident. > The patch should actually have most benefit when you are doing transfers > with smaller packets. I think with larger constant streams like the one > you tested, there will be little difference between bumping up the > interface speed with the patch or leaving it all as it was (at the end > of the day we are mostly just shifting the calculation of interface > speed somewhere else). Without the patch, if I set my rate to 256 * 0.8, I die. The connection is not completely unusable, but gaming is extremely laggy and Web traffic is noticeably laggy, although pages still load with about 2s (versus a few hundred ms without the patch at 160kbit). With the patch I can set it to 224, so there's obviously a large improvement even with mostly large TCP packets going out doing a bulk `scp` copy. > >Perhaps I need to idle everything and do one of those 'speed tests' to see > >what my actual upstream is. Could be it's really around 224, since I'm > > not guaranteed 256 by my ISP anyway. > > Your upstream will be 256Kbits of ATM bandwidth. This consists of 53 > byte packets with 48 bytes of data. So you already only have 256 * > 48/53 of real bandwidth. We then have to take off PPP headers and PPPoE > headers. That's the maximum promised speed from my ISP. In reality, of course, line conditions might result in my true speed not being that high, before accounting for overhead and things. > We are obviously still a few bytes out with this patch or else you > should be able to crank up the speed to 250 ish and still see your ping > speeds stay low. I will investigate further Okay, if you're sure it's not just my line having a true upstream less than the consumer rated speed it was assigned. ;) > Ed W > -- Jason Boxman Perl Programmer / *NIX Systems Administrator Shimberg Center for Affordable Housing | University of Florida http://edseek.com/ - Linux and FOSS stuff _______________________________________________ LARTC mailing list / LARTC@xxxxxxxxxxxxxxx http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
