3Com SECPATH U200-CS Installation Manual page 17

When working in the forced mode, Ethernet does not support MDI/MDIX autosensing.
4) Cable connecting electrical Ethernet interfaces
Ethernet electrical interfaces usually use category-5 twisted pair cables. Ethernet cables fall into two
categories:
Standard cables: Also known as straight-through cables. At both ends of a standard cable, wires
are crimped in the RJ-45 connectors in the same sequence. A straight-through cable is used for
connecting a terminal (for example, a PC or UTM device) to a hub or LAN switch. Straight-through
cables are shipped with the U200 series.
Crossover cables: At both ends of a crossover cable, wires are crimped in the RJ-45 connectors in
different sequences. A crossover cable is used for connecting two terminals (for example, two PCs
or UTM devices). You can make crossover cables yourself as needed.
Figure 1-12 Ethernet cable
Table 1-12 Straight-through cable connector pinouts
RJ-45
1 TX+
2 TX-
3 RX+
4 —
5 —
6 RX-
7 —
8 —
Table 1-13 Crossover cable connector pinouts
RJ-45 Signal direction
1 TX+
2 TX-
3 RX+
Category-5
Signal
twisted pair
White (Orange)
Orange
White (Green)
Blue
White (Blue)
Green
White (Brown)
Brown
Category-5
twisted pair
White (Orange)
Orange
White (Green)
1-11
Signal direction
1
2
3
— 4
— 5
6
— 7
— 8
Signal direction
3
6
1
RJ-45
RJ45