8 pin RJ45 (8P8C) female connector at the Cisco routers.
8 pin RJ45 (8P8C) male connector at the cable.
The Cisco Catalyst 5000 and 5500 Series switches carry an EIA/TIA-232 asynchronous serial console port on the Supervisor Engine, implemented as an 8-position 8-contact (RJ-45) jack. The Supervisor Engine features a physical mode switch: Mode 1 (default, switch pushed in) uses a standard Cisco rollover cable and adapter, whilst Mode 2 (switch out) uses the legacy Supervisor Engine III straight-through cable whose pinout is documented here. Default serial parameters across both modes are 9600 bps, 8 data bits, no parity, 1 stop bit, and no flow control. Pins 1 and 8 are connected internally on the console-device side (CTS looped to RTS), allowing hardware-flow-control-capable terminal software to operate without a full handshake circuit.
| Console Port | Console device |
|---|---|
| Pin | +Signal |
| 1 | looped to 8 |
| 2 | (DTR) |
| 3 | (RxD) |
| 4 | (GND) |
| 5 | (GND) |
| 6 | (TxD) |
| 7 | (DSR) |
| 8 | looped to 1 |
Signals
- DTR — Data Terminal Ready; output from the console device, asserted to indicate the terminal is active.
- RxD — Received Data; serial data input to the console port (data arriving from the terminal).
- GND — Signal Ground; reference for all EIA/TIA-232 signal levels.
- TxD — Transmitted Data; serial data output from the console port (data sent to the terminal).
- DSR — Data Set Ready; input to the console device, indicating the switch is powered and ready.
- Looped to 1/8 — Pins 1 and 8 are connected together internally on the console-device (cable) side, creating a CTS/RTS loop that satisfies terminal emulators expecting hardware flow control without requiring active switching logic in the switch itself.
Notes
- This pinout applies to Mode 2 operation of the Catalyst 5000/5500 Supervisor Engine console port (mode switch in the OUT position). Mode 1 (switch IN, default) uses a reversed RJ-45 assignment compatible with the standard Cisco rollover cable (CAB-500RJ=) plus an RJ-45-to-DB-9 or RJ-45-to-DB-25 DTE adapter.
- The Catalyst 6500 Supervisor Engine 2 shares the same dual-mode console architecture, with Mode 2 matching this Catalyst 5000 Supervisor Engine III pinout exactly.
- The rollover cable (Cisco part CAB-500RJ=) reverses all eight conductors: pin 1↔8, 2↔7, 3↔6, 4↔5. It is used with Mode 1 only; Mode 2 requires a straight-through cable.
- The console port does not support modem control or hardware flow control at the switch; the CTS/RTS loop on pins 1 and 8 is a passive internal short on the terminal-cable side.
- The RJ-45 connector on the Supervisor Engine is the female (jack) receptacle; the cable uses the male plug.