Asynchronous Connections

Introduction

This document describes the text, image, and command conventions used in Cisco technical tips.

General Conventions

Text

• Bold indicates text the user must enter or select, such as menu items, buttons, and commands.

• Italics indicate emphasis.

• Angle brackets (>) indicate the progression of menu choices the user should select in a graphical user interface (GUI), such as File > Print.

• Output examples from Cisco devices are displayed in Courier font; for example:
  

  3524xl# show running-config
  Building configuration...
  
  Current configuration:
  
  !
  version 12.0
  no service pad
  service timestamps debug uptime
  service timestamps log uptime
  no service password-encryption
  !

• System error messages from Cisco devices are displayed in Courier font; for example:

  A router restarted with the reload command displays the System returned to ROM by reload message.

Alerts

Tip  Means the following information will help you solve a problem. The tips information might not be troubleshooting or even an action, but could be useful information.

Note  Means reader take note. Notes contain helpful suggestions or references to material not covered in the document.

Caution  Means reader be careful. In this situation, you might do something that could result in equipment damage or loss of data.

Warning  Warning means danger. You are in a situation that could cause bodily injury. Before you work on any equipment, you must be aware of the hazards involved with electrical circuitry and be familiar with standard practices for preventing accidents. To see translated versions of the warning, refer to the Regulatory Compliance and Safety document thataccompanied your device.

  The exit icon means you are leaving the Cisco website. This image appears after a link to a non-Cisco Systems webpage; Cisco is not responsible for the content of other websites. Links to websites external to Cisco.com open in a separate browser window.

Cisco IOS/CatOS Software Commands

The following conventions for Cisco IOS^® and CatOS commands are also used in the command reference guides. For more information about conventions in Cisco IOS documentation, refer to About Cisco IOS Software Documentation.

• Vertical bars ( | ) separate alternative, mutually exclusive arguments. Example: req-qos {best-effort | controlled-load | guaranteed-delay}

• Square brackets ([ ]) indicate optional elements. Example: [no] ip route-cache [cbus]

• Braces ({ }) indicate a required choice. Example: access-list number [{permit | deny}]

• Braces within square brackets ([{ }]) indicate required choices within optional elements.

• Angle brackets (< >) indicate arguments in contexts that do not allow italics, and in examples indicate character strings a user enters that do not appear on the screen (for example, a password).

• Bold indicates commands and keywords.

• Italics indicate user variables.

Configuration Examples

Generic router names, hostnames, usernames, passwords, and IP addresses are used in configuration examples. These should be replaced with the names, passwords, and addresses appropriate for your company.

Important Note: Do not use username cisco or password cisco in your configurations. To use "cisco" as a password or username, or to use any trivial password, is a security risk.

• Router names: RouterX, nasX, and so on.

• Phone numbers: 555nnnn

• IP addresses: IP addresses conform to RFC 1918 definitions of private network addresses.

  Three blocks of IP addresses are reserved by the Internet Assigned Numbers Authority (IANA) for private Internets:

  • 10.0.0.0 - 10.255.255.255 (10/8 prefix)

  • 172.16.0.0 - 172.31.255.255 (172.16/12 prefix)

  • 192.168.0.0 - 192.168.255.255 (192.168/16 prefix)

• Often comments are included in the configuration examples. Comments are italicized and blue. They provide more information about the configuration output and commands used. Configuration comments appear similar to:

  
  !--- Define IPSec traffic of interest.
  !--- This line covers traffic between the LAN segment behind two PIXes.
  !--- It also covers the SNMP/syslog traffic between the SNMP/syslog server
  !--- and the network devices located on the Ethernet segment behind PIX 515.
  
  access-list 101 permit ip 172.18.124.0 255.255.255.0 10.99.99.0 255.255.255.0