Thanks for your (well written) answers. On Wed, 2002-08-21 at 16:50, Igor Izyumin wrote: > On Wednesday 21 August 2002 08:51 am, Robert Fox wrote: > > Could you please shed some light onto this? I have another notebook > > (Compaq Armada M700) with an integrated network card (non-pcmcia) and it > > works fine at full-duplex. > > Quite possibly. This depends on the network card, the driver, the network > it's hooked up to, and the options passed to it. > > > Where is it documented about these problems with hubs and networks? I > > have yet to find anything on the Internet about this problem. > > See link below. > The referenced link doesn't say anything about problems - it only states that hubs don't support full duplex (therefore the card automatically falls back to half duplex during link negotiation)
> > What I fail to understand is - Why does RedHat, Suse and Microsoft > > (Win2K and WinXP) all configure the Xircom card with full-duplex turned > > on? Also, last I checked - Mandrake 8.2 works fine with full-duplex. > > Possibly because the driver has been updated, and now defaults to a different > setting. If you really want to, you could probably just pass the right > option to the driver. I was just pointing out that it doesn't really matter > for 99% of all users, and thus not worth the effort to troubleshoot and fix. > You hit the nail on the head here!! "defaults to a different setting" - The defaults have changed and I'm asking Mandrake development team to change it back to full-duplex like it was before! > > Why does the DrakX install also initialize the card with full duplex > > during install? > > DrakX uses a different kernel than the regular distribution (I think). The > driver might be different. > Not to my knowledge, and the driver appears to be the same for DrakX and a freshly installed system. > > I also disagree about not seeing a difference between half/full duplex. > > As we all know, duplex is better because both sides can communicate > > simultaneously! > > This is of very dubious benefit for ordinary systems that are not acting as > high-volume servers. Few computers can communicate at wire-speed, due to > protocol overhead and other factors. While theoretically, the available > bandwidth is doubled, it is not so in reality, because clients do not need to > send and receive large amounts of data at the same time at wire-speed. > > Having a USB keyboard doesn't mean you can type on it faster than you can on a > PS/2 keyboard, even though it has more bandwidth. It's not the bottleneck. > The same thing applies to full duplex vs. half-duplex. The bottleneck is > mostly in your computer/protocol, not the wire. > > Here are a few quotes from one document I found: > (http://www.proxim.com/learn/library/guides/gd_halfduplex_ethernet.html) > > " Performance-wise, Full Duplex operation is beneficial primarily to file > servers or similar devices that send and receive traffic simultaneously from > several clients." > > Does your notebook act as a file server? > Point taken - I just wanted to know WHY someone changes the previous defaults and forces the card into half-duplex. There must have been a valid reason for this change . . . > > "Shared hubs do not support Full Duplex mode." > I have a Linksys DSL Router/Switch (10/100) which has a fully switched 100Mbit ports > Therefore, people who use regular hubs instead of switches might have > problems if the default is set to full duplex. > Doubt it - again, a hub would simply force the card into half-duplex mode when it doesn't support it . . . Cheers, R.Fox
