On Sat, Jul 24, 2010 at 10:44:41AM -0400, Valdis.Kletnieks@xxxxxx wrote: > On Fri, 23 Jul 2010 14:57:36 CDT, Bob Tracy said: > > I've got one of the inexpensive Davicom DM9601 USB to fast Ethernet > > devices, commonly available on eBay for under $10 including shipping. > > It works fairly well in a WinXP environment with a MTU of 1000: 1500 > > and 1492 are confirmed not working, and values between 1000 and 1492 > > have not been tested at this point. > > Wow. An "ethernet" card that won't do an MTU of 1500 even under Windows. May I > add this to my gallery of examples I use when people say "no vendor could > *possibly* ship hardware that fscked up"? :) You may :-), although I wouldn't assume the Windows driver is blameless. At 100 Mbit/s, flow-control simply has to work if the device is USB 1.1. According to the data sheet, there's a total of 16 kB of on-chip SRAM available for buffering (oddly enough, the documentation indicates the device *could* support up to 64 kB of SRAM). Gotta shovel out that stall quickly, and I suspect using a smaller MTU is simply giving an inefficient driver more time to do that. If I don't get tired of messing around with this adapter, I may experiment a little to see what happens when I lock the interface speed at 10 Mbit/s (instead of letting it auto-sense). Another respondent said MTU >= 1280 is required for IPv6, so I gave that a try just to see if the floor could be raised a bit above 1000. For what it's worth, 1280 works. --Bob -- To unsubscribe from this list: send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
