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Cisco uBR7100 Series and Cisco uBR7100E Series Universal Broadband Router Hardware Installation Guide
OL-5916-01
Appendix C Cable Specifications
Fast Ethernet Port Cables and Pinouts
Auxiliary Port Cables and Pinouts
Use the RJ-45-to-RJ-45 rollover cable and RJ-45-to-DB-25 male DCE adapter (labeled MODEM) to
connect the auxiliary port to a modem. Table C-2 lists the signals and pinouts for the asynchronous serial
auxiliary port, the RJ-45-to-RJ-45 rollover cable, and the RJ-45-to-DB-25 male DCE adapter (labeled
MODEM).
Fast Ethernet Port Cables and Pinouts
The 10BASE-T/100BASE-TX Fast Ethernet ports support IEEE 802.3 and IEEE 802.3u specifications
for 10-Mbps and 100-Mbps transmission over unshielded twisted-pair (UTP) cables. Each Fast Ethernet
port on the router has an RJ-45 connector to attach to Category 3 or Category 5 UTP cables.
• Use a Category 3 UTP crossover cable when connecting 10BASE-T port to a hub.
• Use a Category 3 UTP straight-through cable when connecting to a PC or other Ethernet device.
• Use a Category 5 UTP crossover cable when connecting 100BASE-TX to a hub.
• Use a Category 5 UTP straight-through cable when connecting to a PC or other Ethernet device.
Note Cisco Systems does not supply Category 3 or Category 5 UTP RJ-45 cables; these cables are available
commercially.
Identifying an RJ-45 Crossover Cable
You can identify a crossover cable by comparing the two modular ends of the cable. Hold the cables
side-by-side with the tab at the back. The first (far left) colored wire (pin 1) at one end of the cable is
the third colored wire (pin 3) at the other end of the cable. The second colored wire (pin 2) at one end
of the cable is the sixth colored wire (pin 6) at the other end of the cable. Pin 1 wire is white.
Table C-2 Auxiliary Port Signaling and Cabling Using a DB-25 Adapter
AUX Port (DTE) RJ-45-to-RJ-45 Rollover Cable
RJ-45-to-DB-25
Modem Adapter Modem (DCE)
Signal RJ-45 Pin RJ-45 Pin DB-25 Pin Signal
RTS 1 8 4 RTS
DTR 2720 DTR
TxD 363 TxD
GND 4 5 7 GND
GND 5 4 7 GND
RxD 6 3 2 RxD
DSR 7 2 8 DCD
CTS 8 1 5 CTS