Understand Cable Requirements for Console and AUX Ports

Introduction

This document describes the cable and connector requirements for console and auxiliary (AUX) ports. 

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

This document is not restricted to specific software and hardware versions.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, ensure that you understand the potential impact of any command.

Conventions

Refer to Cisco Technical Tips Conventions for more information on document conventions.

Background Information

Cisco routers either have RJ-45-based or DB-25 DCE/DTE console and AUX ports. You can connect either a terminal (DTE) or a modem (DCE) to these ports. In either instance, you need both an RJ-45 cable and an RJ-45-to-DB-25 or RJ-45-to-DB-9 connector.

Console Port Settings for Terminal Connection

Before you connect a terminal to the console port, configure the terminal to match the router console port as shown here:

• 9600 baud

• 8 data bits

• No parity

• 2 stop bits (9600 8N2) OR 1 stop bit
  • Dependent on the router.

Types of Console and AUX Connectors

Cisco routers have three types of console and AUX connectors. The table in this section lists these types:

• RJ-45

• DB-25 DCE

• DB-25 DTE

There are three styles of RJ-45-to-DB-25 connectors:

• DCE style (modem)

• DTE style

• DCE style (non-modem)

Each of these styles has a different role. Generally, DTE is for terminals, DCE (modem) is for modems, and DCE (non-modem) is obsolete.

Note: Move pin 6 to pin 8 if you want to change a DCE style (non-modem) to a DCE style (modem).

Console and AUX Connectors for Cisco Routers

Connector	Graphic
RJ-45	RJ-45
DB-25 DCE	DB-25 DCE
DB-25 DTE	DB-25 DTE

Cable for console and AUX port:

• RJ-45 Cables

• RS 232 Straight-through Cable

RJ-45 Cables

Cisco products use these types of RJ-45 cables:

• Straight-through

• Crossover

• Rolled

• RJ-45 to DB9 female

Cisco does not provide these cables. These cables are widely available from other sources. Console cable is usually provided with the Console Cable Kit.

Note: The console port does not support modem control or hardware flow control.

RJ-45 Connector

How to Identify an RJ-45 Cable

In order to identify the RJ-45 cable type, hold the two ends of the cable next to one another so you can see the colored wires inside the ends, as shown here:

RJ-45 Cable Ends

There are three types of commonly used RJ-45 cables: straight, cross and rolled. Hold the two ends of an RJ-45 cable side by side. There are eight colored strips, or pins, at each end. If the order of the colored pins is the same at each end, the cable is straight. If the order of the colors is reversed at each end, the cable is rolled.

Examine the sequence of colored wires to determine the type of RJ-45 cable. This section explains how you can do this.

Straight-through Cable

In a straight-through cable, the colored wires are in the same sequence at both ends of the cable.

Straight-through Cable

Straight-through Cable

RJ-45 Straight-through (Ethernet) Cable Pin-outs

Crossover Cable

In a crossover cable, the first (far left) colored wire at one end of the cable is the third colored wire at the other end of the cable.

Crossover Cable

Crossover Cable

RJ-45 Crossover (Ethernet) Cable Pin-outs

Rolled Cable

In a rolled cable, the colored wires at one end of the cable are in the reverse sequence of the colored wires at the other end of the cable.

Rolled Cable

Rolled Cable

Rolled Cable Pin-outs

Note: CAB-OCTAL-ASYNC, the 8-port RJ-45 adapter that is used with the Cisco 2509, 2510, 2511, and 2512, is the same as a rolled cable.

RJ-45 to DB-9 Female*

RJ-45 to DB-9 Female*

This cable is also known as Management Cable.

• Cisco provides this cable with the 600, 800, 1600 and 1700 Series Routers.

Type of Cable for DB-25 Connectors

RS 232 Straight-through Cable

This illustration shows serial cable CAB-R23= (part number 74-0173), which is a general serial cable for all router platforms:

Both Ends of RS 232 Straight-through Cable for DB-25 Connectors

Both Ends of RS 232 Straight-through Cable for DB-25 Connectors

This cable has a female DB-25 connector on one end and a male DB-25 connector on the other end. Either end of the CAB-R23 cable can be the Cisco end or the network end, based on whether the Cisco router is designated as a DCE device or a DTE device. If the router is designated as a DCE device, the female DB-25 connector is the Cisco end. If the router is designated as a DTE device, the male DB-25 connector is the Cisco end.

Pin-outs for RS 232 Straight Through Cable (DB-25)

Adapters

You need two types of adapters to connect a PC to a router.

• RJ-45-to-DB-9 Adapter

• RJ-45-to-DB-25 Adapter

RJ-45-to-DB-9 Adapter

This adapter connects a router to a PC though a COM port.

RJ-45-to-DB-9 Adapter

RJ-45-to-DB-9 Adapter

RJ-45-to-DB-25 Adapter

This adapter connects a router to PC through a serial port.

RJ-45-to-DB-25 Adapter

RJ-45-to-DB-25 Adapter-Female Adapter

Cable and Adapter Setups that Work

Here are the most common ways to console into a router.

Console Connection Combination

Console Port	Cable	Adapter for PC	Adapter for Console Port
RJ-45	RJ-45 Rolled	DB-9 / DB-25	None
DB9-RJRT Adapter-Rolled Over RJ-45 Cable
DB-25 DCE	RJ-45 Rolled	DB-9 / DB-25	RJ-45-to-DB-25
DB-25 DCE	DB-25	None	None
DB-25 DCE, DB-25, None, None
RJ-45	RJ-45-to-DB-9	None	None

• Cisco provides this cable with the Cisco 600, 800, 1600 and 1700 Series Routers.

You cannot mix and match these components randomly. Here are the combinations that work:

Console Connection Combination

These are the only setups that work. If you do not have the components you need, use the RJ-45 Component Guide chart to order them.

RJ-45 Port and Adapter Pin-outs

This chart shows the pin-outs for RJ-45 console and AUX ports. The console port does not use RTS/CTS.

RJ-45 Port Pin-outs

DB-25 Console and AUX Port Pin-outs

Console Port Signals

Note: The console port does not support modem control or hardware flow control.

Auxiliary Port Signals

Note: The auxiliary port supports hardware flow control and modem control.

Console Cable Kit

A console cable kit is provided with your router. Use this kit when you connect your router to a PC or a terminal.

The console cable kit contains these items:

• RJ-45-to-RJ-45 console cable (blue)

• RJ-45-to-DB-25 adapter (gray)

• RJ-45-to-DB-9 adapter (gray)

Note: The Cisco 7200 Series and Cisco 7301 are not shipped by default with a console cable kit. If a console cable is required, order an accessory kit (part number: ACS-2500ASYN).

RJ-45-to-RJ-45 console cable	RJ-45-to-DB-25 adapter	RJ-45-to-DB-9 adapter
RJ-45-to-RJ-45 Console Cable	RJ-45-to-DB-25 Adapter	DB-9-to-RJ-45 Console Adapter

Cisco RJ-45 Component Guide

This chart summarizes the RJ-45 components of Cisco:

RJ-45 Component Guide

The first seven entries are DB-25 connectors, and the last two are RJ-45 cables. Connectors are described in terms of their sex and their role. For example, an FDTE is a female DTE style connector, an MMOD is a male modem style connector, and so on. Again, you need shielded cables in order to run at 115.2 kbps.

Related Information

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