Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide

Using Cisco IOS XE Software

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This chapter provides information to prepare you to configure the Cisco ASR 1000 Series Routers:

• Accessing the CLI Using a Router Console
• Using Keyboard Shortcuts
• Using the History Buffer to Recall Commands
• Understanding the Command Mode
• Understanding the Diagnostic Mode
• Getting Help
• Using the no and default Forms of Commands
• Saving Configuration Changes
• Managing Configuration Files
• Filtering the Output of the show and more Commands
• Powering Off a Router
• Finding Support Information for Platforms and Cisco Software Images

Accessing the CLI Using a Router Console

The following sections describe how to access the command-line interface (CLI) using a directly-connected console or by using Telnet or a modem to obtain a remote console:

• Accessing the CLI Using a Directly-Connected Console
• Accessing the CLI from a Remote Console Using Telnet

Accessing the CLI Using a Directly-Connected Console

This section describes how to connect to the console port on the router and use the console interface to access the CLI.

The console port on a Cisco ASR 1000 Series Router is an EIA/TIA-232 asynchronous, serial connection with no flow control and an RJ-45 connector. The console port is located on the front panel of each Route Processor (RP).

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Note Cisco ASR 1000 Series Router auxiliary port does not support modem.

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Preparing to Connect to the Router Console Using Telnet

Before you can access the router remotely using Telnet from a TCP/IP network, you need to configure the router to support virtual terminal lines (vtys) using the line vty global configuration command. You also should configure the vtys to require login and specify a password.

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Note To prevent disabling login on the line, be careful that you specify a password with the password command when you configure the login line configuration command. If you are using authentication, authorization, and accounting (AAA), you should configure the login authentication line configuration command. To prevent disabling login on the line for AAA authentication when you configure a list with the login authentication command, you must also configure that list using the aaa authentication login global configuration command. For more information about AAA services, see the Cisco IOS XE Security Configuration Guide, and the Cisco IOS Security Command Reference Guide.

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In addition, before you can make a Telnet connection to the router, you must have a valid host name for the router or have an IP address configured on the router. For more information about requirements for connecting to the router using Telnet, information about customizing your Telnet services, and using Telnet key sequences, see the Cisco IOS Configuration Fundamentals Configuration Guide.

Using Telnet to Access a Console Interface

To access a console interface using Telnet, complete the following steps:

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Step 1 From your terminal or PC, enter one of the following commands:

• connect host [ port ] [ keyword ]
• telnet host [ port ] [ keyword ]

In this syntax, host is the router hostname or an IP address, port is a decimal port number (23 is the default), and keyword is a supported keyword. For more information, see the Cisco IOS Configuration Fundamentals Command Reference Guide.

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Note If you are using an access server, then you will need to specify a valid port number such as telnet 172.20.52.40 2004, in addition to the hostname or IP address.

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The following example shows the telnet command to connect to the router named router:

unix_host% telnet router

Trying 172.20.52.40...

Connected to 172.20.52.40.

Escape character is '^]'.

unix_host% connect

 

Step 2 At the password prompt, enter your login password. The following example shows entry of the password mypass:

 

User Access Verification

 

Password: mypass

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Note If no password has been configured, press Return.

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Step 3 From user EXEC mode, enter the enable command as shown in the following example:

Router> enable

 

Step 4 At the password prompt, enter your system password. The following example shows entry of the password enablepass:

Password: enablepass

 

Step 5 When the enable password is accepted, the privileged EXEC mode prompt appears:

Router#

 

Step 6 You now have access to the CLI in privileged EXEC mode and you can enter the necessary commands to complete your desired tasks.

Step 7 To exit the Telnet session, use the exit or logout command as shown in the following example:

Router# logout

 

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Using Keyboard Shortcuts

Commands are not case sensitive. You can abbreviate commands and parameters if the abbreviations contain enough letters to be different from any other currently available commands or parameters.

Table 3-1 lists the keyboard shortcuts for entering and editing commands.

Using the History Buffer to Recall Commands

The history buffer stores the last 20 commands you entered. History substitution allows you to access these commands without retyping them, by using special abbreviated commands.

Table 3-2 lists the history substitution commands.

Understanding the Command Mode

The command modes available in the traditional Cisco IOS CLI are exactly the same as the command modes available in Cisco IOS XE.

You use the CLI to access Cisco IOS XE software. Because the CLI is divided into many different modes, the commands available to you at any given time depend on the mode that you are currently in. Entering a question mark (?) at the CLI prompt allows you to obtain a list of commands available for each command mode.

When you log in to the CLI, you are in user EXEC mode. User EXEC mode contains only a limited subset of commands. To have access to all commands, you must enter privileged EXEC mode, normally by using a password. From privileged EXEC mode, you can issue any EXEC command—user or privileged mode—or you can enter global configuration mode. Most EXEC commands are one-time commands. For example, show commands show important status information, and clear commands clear counters or interfaces. The EXEC commands are not saved when the software reboots.

Configuration modes allow you to make changes to the running configuration. If you later save the running configuration to the startup configuration, these changed commands are stored when the software is rebooted. To enter specific configuration modes, you must start at global configuration mode. From global configuration mode, you can enter interface configuration mode and a variety of other modes, such as protocol-specific modes.

ROM monitor mode is a separate mode used when the Cisco IOS XE software cannot load properly. If a valid software image is not found when the software boots or if the configuration file is corrupted at startup, the software might enter ROM monitor mode.

Table 3-3 describes how to access and exit various common command modes of the Cisco IOS XE software. It also shows examples of the prompts displayed for each mode.

Understanding the Diagnostic Mode

Diagnostic mode is new on the Cisco ASR 1000 Series Routers.

The router boots up or accesses diagnostic mode in the following scenarios:

• The IOS process or processes fail, in some scenarios. In other scenarios, the RP will simply reset when the IOS process or processes fail.
• A user-configured access policy was configured using the transport-map command that directs the user into diagnostic mode.
• The router was accessed using a Route Processor auxiliary port.
• A send break signal (Ctrl-C or Ctrl-Shift-6) was entered while accessing the router, and the router was configured to enter diagnostic mode when a break signal was sent.

In diagnostic mode, a subset of the commands that are also available in User EXEC mode are made available to users. Among other things, these commands can be used to:

• Inspect various states on the router, including the IOS state.
• Replace or roll back the configuration.
• Provide methods of restarting the IOS or other processes.
• Reboot hardware, such as the entire router, an RP, an ESP, a SIP, a SPA, or possibly other hardware components.
• Transfer files into or off of the router using remote access methods such as FTP, TFTP, SCP, and so on.

The diagnostic mode provides a more comprehensive user interface for troubleshooting than previous routers, which relied on limited access methods during failures, such as ROMmon, to diagnose and troubleshoot IOS problems.

The diagnostic mode commands are stored in the nonIOS packages on the Cisco ASR 1000 Series Routers, which is why the commands are available even if the IOS process is not working properly. Importantly, all the commands available in diagnostic mode are also available in privileged EXEC mode on the router even during normal router operation. The commands are entered like any other commands in the privileged EXEC command prompts when used in privileged EXEC mode.

Getting Help

Entering a question mark ( ?) at the CLI prompt displays a list of commands available for each command mode. You can also get a list of keywords and arguments associated with any command by using the context-sensitive help feature.

To get help specific to a command mode, a command, a keyword, or an argument, use one of the commands listed in Table 3-4 :

Using the no and default Forms of Commands

Almost every configuration command has a no form. In general, use the no form to disable a function. Use the command without the no keyword to re-enable a disabled function or to enable a function that is disabled by default. For example, IP routing is enabled by default. To disable IP routing, use the no ip routing command; to re-enable IP routing, use the ip routing command. The Cisco IOS software command reference publications provide the complete syntax for the configuration commands and describe what the no form of a command does.

Many CLI commands also have a default form. By issuing the command default command-name, you can configure the command to its default setting. The Cisco IOS software command reference publications describe the function of the default form of the command when the default form performs a different function than the plain and no forms of the command. To see what default commands are available on your system, enter default ? in the appropriate command mode.

Saving Configuration Changes

Use the copy running-config startup-config command to save your configuration changes to the startup configuration so that the changes will not be lost if the software reloads or a power outage occurs. For example:

It might take a minute or two to save the configuration. After the configuration has been saved, the following output appears:

This task saves the configuration to NVRAM.

Managing Configuration Files

On the Cisco ASR 1000 Series Routers, the startup configuration file is stored in the nvram: file system and the running-configuration files are stored in the system: file system. This configuration file storage setup is not unique to the Cisco ASR 1000 Series Routers and is used on several Cisco router platforms.

As a matter of routine maintenance on any Cisco router, users should backup the startup configuration file by copying the startup configuration file from NVRAM onto one of the router’s other file systems and, additionally, onto a network server. Backing up the startup configuration file provides an easy method of recovering the startup configuration file in the event the startup configuration file in NVRAM becomes unusable for any reason.

The copy command can be used to backup startup configuration files. The following examples show the startup configuration file in NVRAM being backed up:

Example 1: Copying a Startup Configuration File to Bootflash

Example 2: Copying a Startup Configuration File to USB Flash Disk

Example 3: Copying a Startup Configuration File to a TFTP Server

For more detailed information on managing configuration files, see the Managing Configuration Files section in the Cisco IOS XE Configuration Fundamentals Configuration Guide .

Filtering the Output of the show and more Commands

You can search and filter the output of show and more commands. This functionality is useful if you need to sort through large amounts of output or if you want to exclude output that you need not see.

To use this functionality, enter a show or more command followed by the “pipe” character ( |); one of the keywords begin, include, or exclude ; and a regular expression on which you want to search or filter (the expression is case sensitive):

show command | { append | begin | exclude | include | redirect | section | tee } regular-expression

The output matches certain lines of information in the configuration file. The following example illustrates how to use output modifiers with the show interface command when you want the output to include only lines in which the expression “protocol” appears:

Powering Off a Router

Before you turn off a power supply, make certain the chassis is grounded and you perform a soft shutdown on the power supply. Not performing a soft shutdown will often not harm the router, but may cause problems in certain scenarios.

To perform a soft shutdown before powering off the router, enter the reload command to halt the system and then wait for ROM Monitor to execute before proceeding to the next step.

The following screenshot shows an example of this process:

Place the power supply switch in the Off position after seeing this message.

Finding Support Information for Platforms and Cisco Software Images

Cisco software is packaged in feature sets consisting of software images that support specific platforms. The feature sets available for a specific platform depend on which Cisco software images are included in a release. To identify the set of software images available in a specific release or to find out if a feature is available in a given Cisco IOS XE software image, you can use Cisco Feature Navigator or the software release notes.