B-3
Catalyst 3550 Multilayer Switch Hardware Installation Guide
OL-6155-01
Appendix B Connector and Cable Specifications
Cable and Adapter Specifications
Cable and Adapter Specifications
These sections describe the cables and adapters used with the Catalyst 3550 switches.
Two Twisted-Pair Cable Pinouts
Figure B-4 and Figure B-5 show the schematics of two twisted-pair cables for ports running
10 Mbps traffic.
Figure B-4 Two Twisted-Pair Straight-Through Cable Schematic
Figure B-5 Two Twisted-Pair Crossover Cable Schematic
Four Twisted-Pair Cable Pinouts for 10/100 Ports
Figure B-6 and Figure B-7 show the schematics of four twisted-pair cables for ports running 10 or 100
Mbps traffic.
For inline power connections, signal pairs are used to provide inline power. Nominally, there is 48 V
between the pin pairs (1–2), and pairs (3–6) when inline power is active.
Figure B-6 Four Twisted-Pair Straight-Through Cable Schematic for 10/100 Ports
Switch
3 TD+
6 TD–
1 RD+
2 RD–
Router or PC
3 RD+
6 RD–
1 TD+
2 TD–
H5578
Switch
3 TD+
6 TD–
1 RD+
2 RD–
Switch
3 TD+
6 TD–
1 RD+
2 RD–
H5579
1 RD+
2 RD-
3 TD+
6 TD-
1 TD+
Switch Router or PC
2 TD-
3 RD+
6 RD-
4NC
5NC
7NC
8NC
4NC
5NC
7NC
8NC
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