On Mon, 8 Oct 2001, Paul Lussier wrote: > Well, in theory, I think it depends upon the protocol, but I think in > general, the cards will auto-negotiate with whatever network equipment > they're connected to.
In theory, it will work that way. Personally, I want to move to Theory. Everything works in Theory. :-) > The 10Mb ethernet spec I believe calls for 10Mb HD, whereas the 100Mb > spec calls for 100Mb FD. The 100 Mbit specs do not require FDX. They do not even require auto-negotiation. It is quite possible to have a single-speed, half-duplex, 100 Mbit/sec repeater (which will not even work at 10 Mbit). > I'm not sure what the 1000Mb calls for, but I would imagine that it > would be FD as well. I think gigabit requires FDX. My understanding of gigabit is that the underlying implementation is quite a bit different than traditional Ethernet; just the presentation is similar. However, I only worked with it when the technology was still relatively new, and then only briefly, so I'm probably wrong. Given that I learned this stuff at Cabletron, you might want to upgrade that to "definitely wrong". ;-) > Once you move to UTP (or multi-mode fiber), though, you now have 2 > channels for the datastream to travel over, thus allowing for FD > connectivity. You also need equipment capable of handling it. In particular, you cannot do FDX with a repeater. You need a switch. > ... because all that negotiation is performed at the physical layer of > the NIC itself. While I have never written a driver, I have seen at least a few cases where the driver was apparently heavily involved in negotiation. I imagine the hardware could be quite "dumb", requiring intelligence from the software to supervise things. Remember, one of the selling points of Ethernet is the extremely simple protocol means extremely simply hardware is possible. :-) > That being said, auto-negotiation is a horrible and bug-ridden spec. I cannot comment on the spec, but I do know that given the "cheap" nature of Ethernet, bug-ridden *implementations* are very common. People cannot seem to understand why their $5 Ethernet adapter with no documentation and a hand-lettered floppy disk doesn't work right. :-) -- Ben Scott <[EMAIL PROTECTED]> | The opinions expressed in this message are those of the author and do not | | necessarily represent the views or policy of any other person, entity or | | organization. All information is provided without warranty of any kind. | ********************************************************** To unsubscribe from this list, send mail to [EMAIL PROTECTED] with the following text in the *body* (*not* the subject line) of the letter: unsubscribe gnhlug **********************************************************
