Messages in this thread | | | From | Steven Bonneville <> | Subject | Re: Linux 2.2.2 TCP delays every 41st small packet by 10-20 ms | Date | Fri, 26 Feb 1999 09:33:28 -0600 (CST) |
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Donald Becker <becker@cesdis.gsfc.nasa.gov> wrote:
> Full duplex mode never has collisions. > You were likely trying to use full duplex mode on a CSMA/CD Ethernet. > Full duplex can only be used on host-to-host and host-to-switch links, and > only when both endpoints are configured or negotiate full duplex. > > Full duplex can never be used when there is a repeater (aka hub) in the > network. Spank yourself if you configured FDX in that case.
Actually, 3Com's muddied this a bit with their Hub 1000 SX Gigabit Ethernet full-duplex repeater. They pull this off by using some sort of round-robin internal negotiation instead of CSMA/CD to give ports access to the internal bus; but all traffic still goes out all ports. I don't know much more about it than that. So you can't do full-duplex with CSMA/CD Ethernet (which was your point, of course), but weird repeaters exist that avoid collisions and can do full-duplex.
It's a fine point though; in most cases that spanking is well deserved. :)
-- Steve Bonneville
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