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Home » Forums » Forum Archives » Networking and Internet Sharing » Topic # 247

full duplex
side Sep-13-00 08:23 PM
LAST EDITED ON Sep-13-00 AT 08:24 PM (GMT)

A nic working a full duplex need a utp cable 200 Mhz or a 100 Mhz cable cat 5 is ok .


tks


1. RE: full duplex
lbyard Sep-13-00 08:45 PM
In response to message 0
LAST EDITED ON Sep-13-00 AT 08:47 PM (GMT)

See http://duxcw.com/digest/Howto/network/cable/cable5.htm for a diagram. You have two pairs of wires connecting two sets of receivers and transmitters. Half-duplex: one pair at a time is sending data. Full-duplex, both pairs can send/receive data simultaneously. Theoretically, each pair can transmit data at 100 Mhz. Full-duplex = 100 + 100 (two 100 Mhz lines) = 200 Mhz. A switch can go full duplex because it switches one pair of computers, etc. into its own little network called a network segment (the equivalent of two devices/computers being temporarily connected directly together by a crossover cable). A hub does not switch pairs of ports together; it simply retransmits packets from all ports to all ports, it is one segment. With a hub, packets can collide; with a switch they do not/cannot collide. Therefore, a hub cannot operate at full duplex; one of the pairs is used to “listen” for collisions (again two 100 Mhz lines: one listens at 100 Mhz while the other transmits at 100 Mhz). A switch can operate at full-duplex because there are no collisions and no need to listen for them. But it really doesn’t make any difference in a small network. The network in both cases is faster than the computers connected to it (see benchmarks at the bottom of http://duxcw.com/digest/Reviews/Network/smc/smc7004br/smc7004br-2.htm). The answer, which now you might understand a little better, is that 100 Mhz cable will work in both situations (CAT 5 or CAT 5E, or higher). Larry


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