Transition Networks E-PSW-TX-02 Straight-Through/Crossover 10BASE-T /100BASE-TX, D C, crossover

Installing Network Cable (continued)

Straight-Through/Crossover (10BASE-T /100BASE-TX)

The most popular wiring used today, unshielded twisted-pair copper cable, is used for 10BASE-T and for 100BASE-TX. As with 10BASE-T, the transmit and receive data signals on each pair of a 100BASE-TX segment are polarized, with one wire of each signal pair carrying the positive (+) signal, and the other carrying the negative (-) signal. The pin numbers used in the eight-pin connector for 100BASE-TX conform to the wiring scheme already in use in the 10BASE-T standard, so a 100BASE-TX board can replace a 10BASE-T board in a Category 5 wiring system without any wiring changes.

The straight-through/crossover rule	1 2 3 4	5 6 7 8
that applies to 10BASE-T also applies
to 100BASE-TX. The 10BASE-T and
100BASE-TX cable and RJ-45 jacks for
Switch to Terminal connections must

Eliminating CSMA/CD collisions on the segment by installing full- duplex cards at the network interfaces in a network with Category 5 cables already installed allows a minimum investment to effectively double the network collision domain diameter.

			D	Collisio
				n	Do
		A/C				m	ai
	M
S								n
C

10Mb/s 100 meters

Install Transition Networks' Pocket Switch

AND Install Full-Duplex 10BASE-T Card in Server For Collision-Free Full-Duplex Connection to Serve

be configured as straight-through. The
10BASE-T and 100BASE-TX cable and	8	RJ-45 PLUG
RJ-45 jacks for Switch to Hub	1
	RJ-45 JACK
connections must be configured as
crossover.
Straight-Through Cable
at RJ-45 Plug
Switch . . . . . . . . . . . . . .PC, transceiver, The two active pairs in a

F

			lex Ethern	e	t
		p				™
	u
	D
l
l
u

20Mb/s 100 meters

Li n

k

			D C	ol
	/			lision	D
	A	C				o
	M					m
						a
	S					n
C						i

10 Mb/s

100 meters

	NIC, printer	10BASE-T network are pins 1
RJ-45 Male	.RJ-45 Male
		& 2 and pins 3 & 6. Use only
1 . . . .	. . .1
		dedicated wire pairs (such as
2 . . .	. . .2
		blue/white & white/blue,
3 . . .	. . .3
		orange/white & white/orange)
6 . . . .	. . .6
		for the active pins.

Application behavior determines if a station can take advantage of the increased network capacity of full-duplex. Typical applications do not use bandwidth symmetrically. File transfers, for example, are asymmetrical in nature; bulk data is transferred in one direction, with short acknowledgments returned in the reverse direction. A station which is only doing file transfers will not benefit from the doubling of

The two wires in each pair of the cable must be twisted together for the entire length of the segment and kept twisted to within approximately 1/2 inch of any connector to ensure the integrity of the signal-carrying characteristics of the unshielded wire pair.

Crossover Cable

at RJ-45 Plug

Switch . . . . . . . . . . . . .Hub

RJ-45 Male . . . . . . . . . . . . . . .RJ-45 Male

1 . . . . . . . . . . . . . . . . . . .3 2 . . . . . . . . . . . . . . . . . . .6 3 . . . . . . . . . . . . . . . . . .1 6 . . . . . . . . . . . . . . . . . .2

bandwidth offered by full-duplex switching.

When multiple applications are using the network simultaneously on a single device, the benefits of full-duplex are apparent. Typically servers handle simultaneous network traffic to and from multiple workstations. While any given workstation is using the network asymmetrically, the server can take advantage of full-duplex operation to simultaneously handle transfers in from one station and out to another.

19 Transition Networks’ Pocket Switch 8