This chapter provides information to prepare you to configure the Cisco ASR 920 Series Router:
Understanding Command Modes
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.
The table below 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.
| Command Mode | Access Method | Prompt | Exit Method |
|---|---|---|---|
| User EXEC | Log in. | | Use the logout command. |
| Privileged EXEC | From user EXEC mode, use the enable EXEC command. | | To return to user EXEC mode, use the disable command. |
| Global configuration | From privileged EXEC mode, use the configure terminal privileged EXEC command. | | To return to privileged EXEC mode from global configuration mode, use the exit or end command. |
| Interface configuration | From global configuration mode, specify an interface using an interface command. | | To return to global configuration mode, use the exit command. To return to privileged EXEC mode, use the end command. |
| Diagnostic | The router boots up or accesses diagnostic mode in the following scenarios:
| | If the IOS process failing is the reason for entering diagnostic mode, the IOS problem must be resolved and the router rebooted to get out of diagnostic mode. If the router is in diagnostic mode because of a transport-map configuration, access the router through another port or using a method that is configured to connect to the Cisco IOS CLI. If the router is accessed through the Route Switch Processor auxiliary port, access the router through another port. Accessing the router through the auxiliary port is not useful for customer purposes anyway. |
| ROM monitor | From privileged EXEC mode, use the reload EXEC command. Press the Break key during the first 60 seconds while the system is booting. | | To exit ROM monitor mode, use the continue command. |
Accessing the CLI Using a Router Console
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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.
The table below lists the keyboard shortcuts for entering and editing commands.
| Keystrokes | Purpose |
|---|---|
| Ctrl-B or the Left Arrow key1 | Move the cursor back one character |
| Ctrl-F orthe Right Arrow key1 | Move the cursor forward one character |
| Ctrl-A | Move the cursor to the beginning of the command line |
| Ctrl-E | Move the cursor to the end of the command line |
| Esc B | Move the cursor back one word |
| Esc F | Move the cursor forward one word |
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.
The table below lists the history substitution commands.
| Command | Purpose |
|---|---|
| Ctrl-P or the Up Arrow key2 | Recall commands in the history buffer, beginning with the most recent command. Repeat the key sequence to recall successively older commands. |
| Ctrl-N or the Down Arrow key1 | Return to more recent commands in the history buffer after recalling commands with Ctrl-P or the Up Arrow key. |
| While in EXEC mode, list the last several commands you have just entered. |
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 following commands:
| Command | Purpose |
|---|---|
| Provides a brief description of the help system in any command mode. |
| Provides a list of commands that begin with a particular character string. (No space between command and question mark.) |
| Completes a partial command name. |
| Lists all commands available for a particular command mode. |
| Lists the keywords or arguments that you must enter next on the command line. (Space between command and question mark.) |
Finding Command Options Example
This section provides an example of how to display syntax for a command. The syntax can consist of optional or required keywords and arguments. To display keywords and arguments for a command, enter a question mark (?) at the configuration prompt or after entering part of a command followed by a space. The Cisco IOS XE software displays a list and brief description of available keywords and arguments. For example, if you were in global configuration mode and wanted to see all the keywords or arguments for the arap command, you would type arap ?.
The <cr> symbol in command help output stands for "carriage return." On older keyboards, the carriage return key is the Return key. On most modern keyboards, the carriage return key is the Enter key. The <cr> symbol at the end of command help output indicates that you have the option to press Enter to complete the command and that the arguments and keywords in the list preceding the <cr> symbol are optional. The <cr> symbol by itself indicates that no more arguments or keywords are available and that you must press Enter to complete the command.
The table below shows examples of how you can use the question mark ( ? ) to assist you in entering commands.
| Command | Comment |
|---|---|
| Enter the enable command and password to access privileged EXEC commands. You are in privileged EXEC mode when the prompt changes to a "# " from the "> "; for example,Router> to Router# . |
| Enter the configure terminal privileged EXEC command to enter global configuration mode. You are in global configuration mode when the prompt changes to Router(config)# . |
| Enter interface configuration mode by specifying the serial interface that you want to configure using the gigabitethernet or tengigabitethernet global configuration command. |
| Enter ? to display a list of all the interface configuration commands available for the serial interface. This example shows only some of the available interface configuration commands. |
| Enter the command that you want to configure for the interface. This example uses the ip command. Enter ? to display what you must enter next on the command line. This example shows only some of the available interface IP configuration commands. |
| Enter the command that you want to configure for the interface. This example uses the ip address command. Enter ? to display what you must enter next on the command line. In this example, you must enter an IP address or the negotiated keyword. A carriage return (<cr>) is not displayed; therefore, you must enter additional keywords or arguments to complete the command. |
| Enter the keyword or argument that you want to use. This example uses the 172.16.0.1 IP address. Enter ? to display what you must enter next on the command line. In this example, you must enter an IP subnet mask. A <cr> is not displayed; therefore, you must enter additional keywords or arguments to complete the command. |
| Enter the IP subnet mask. This example uses the 255.255.255.0 IP subnet mask. Enter ? to display what you must enter next on the command line. In this example, you can enter the secondary keyword, or you can press Enter. A <cr> is displayed; you can press Enter to complete the command, or you can enter another keyword. |
| In this example, Enter is pressed to complete the command. |
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 XE 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 XE 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:
Router# copy running-config startup-configBuilding configuration...It might take a minute or two to save the configuration. After the configuration has been saved, the following output appears:
[OK]Router#This task saves the configuration to NVRAM.
Managing Configuration Files
On the router, 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 router 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. Below are some examples showing the startup configuration file in NVRAM being backed up:
Example 1: Copying Startup Configuration File to Bootflash
Router# dir bootflash:Directory of bootflash:/ 11 drwx 16384 Feb 2 2000 13:33:40 +05:30 lost+found15105 drwx 4096 Feb 2 2000 13:35:07 +05:30 .ssh45313 drwx 4096 Nov 17 2011 17:36:12 +05:30 core75521 drwx 4096 Feb 2 2000 13:35:11 +05:30 .prst_sync90625 drwx 4096 Feb 2 2000 13:35:22 +05:30 .rollback_timer105729 drwx 8192 Nov 21 2011 22:57:55 +05:30 tracelogs30209 drwx 4096 Feb 2 2000 13:36:17 +05:30 .installer1339412480 bytes total (1199448064 bytes free)Router# copy nvram:startup-config bootflash:Destination filename [startup-config]? 3517 bytes copied in 0.647 secs (5436 bytes/sec)Router# dir bootflash:Directory of bootflash:/ 11 drwx 16384 Feb 2 2000 13:33:40 +05:30 lost+found15105 drwx 4096 Feb 2 2000 13:35:07 +05:30 .ssh45313 drwx 4096 Nov 17 2011 17:36:12 +05:30 core75521 drwx 4096 Feb 2 2000 13:35:11 +05:30 .prst_sync90625 drwx 4096 Feb 2 2000 13:35:22 +05:30 .rollback_timer 12 -rw- 0 Feb 2 2000 13:36:03 +05:30 tracelogs.878105729 drwx 8192 Nov 21 2011 23:02:13 +05:30 tracelogs30209 drwx 4096 Feb 2 2000 13:36:17 +05:30 .installer 13 -rw- 1888 Nov 21 2011 23:03:17 +05:30 startup-config1339412480 bytes total (1199439872 bytes free)Example 2: Copying Startup Configuration File to USB Flash Disk
Router# dir usb0:Directory of usb0:/43261 -rwx 208904396 May 27 2008 14:10:20 -07:00 asr920-adventerprisek9.02.01.00.122-33.XNA.bin2 55497216 bytes total (40190464 bytes free)Router# copy nvram:startup-config usb0:Destination filename [startup-config]? 3172 bytes copied in 0.214 secs (14822 bytes/sec)Router# dir usb0:Directory of usb0:/43261 -rwx 208904396 May 27 2008 14:10:20 -07:00 asr920-adventerprisek9.02.01.00.122-33.XNA.bin43262 -rwx 3172 Jul 2 2008 15:40:45 -07:00 startup-config 255497216 bytes total (40186880 bytes free)Example 3: Copying Startup Configuration File to a TFTP Server
Router# copy bootflash:startup-config tftp:Address or name of remote host []? 172.17.16.81Destination filename [pe24_asr-1002-confg]? /auto/tftp-users/user/startup-config!!3517 bytes copied in 0.122 secs (28828 bytes/sec)For more detailed information on managing configuration files, see the Configuration Fundamentals Configuration Guide, Cisco IOS XE Release 3S.
Filtering Output from 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:
Router# show interface | include protocolFastEthernet0/0 is up, line protocol is upSerial4/0 is up, line protocol is upSerial4/1 is up, line protocol is upSerial4/2 is administratively down, line protocol is downSerial4/3 is administratively down, line protocol is downPowering Off the 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:
Router# reloadProceed with reload? [confirm]*Jun 18 19:38:21.870: %SYS-5-RELOAD: Reload requested by console. Reload Reason: Reload command.Place the power supply switch in the Off position after seeing this message.
Password Recovery
![Cisco ASR 920 Router Series Configuration Guide, Cisco IOS XE 16 - Using Cisco IOS XE Software [Cisco IOS XE Gibraltar 16.12.1] (3)](https://i0.wp.com/www.cisco.com/content/dam/en/us/td/i/templates/warn.gif "Cisco ASR 920 Router Series Configuration Guide, Cisco IOS XE 16 - Using Cisco IOS XE Software [Cisco IOS XE Gibraltar 16.12.1] (3)") Warning | You will loose the startup configuration by using this Password Recovery procedure. |
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Before you Begin:
Make sure that the hyperterminal has the following settings:
-
9600 baud rate
-
No parity
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8 data bits
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1 stop bit
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No flow control
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Use the power switch to turn off the router and then turn it on again.
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Press Break on the terminal keyboard within 60 seconds of power up to put the router into ROMMON. In some cases Ctrl+Break key combination can be used.
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Type confreg 0x2142 at the ROMMON. 1> confreg 0x2142 1>syncThe router reboots, but ignores the saved configuration.
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The router will reload and prompt for configuration.Type no after each setup question, or press Ctrl-C to skip the initial setup procedure.
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Type enable at the Router> prompt.
You are now in enable mode and should see the Router# prompt.
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Reset the config-register from 0x2142 to 0x2102. To do so, type the following:
config-register configuration_register_setting
Where, configuration_register_setting is 0x2102. For example,
(config)# config-register 0x2102
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.
Using Cisco Feature Navigator
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Using Software Advisor
To see if a feature is supported by a Cisco IOS XE release, to locate the software document for that feature, or to check the minimum software requirements of Cisco IOS XE software with the hardware installed on your router, Cisco maintains the Software Advisor tool on Cisco.com at http://www.cisco.com/cgi-bin/Support/CompNav/Index.pl.
You must be a registered user on Cisco.com to access this tool.
Using Software Release Notes
Cisco IOS XE software releases include release notes that provide the following information:
- Platform support information
- Memory recommendations
- New feature information
- Open and resolved severity 1 and 2 caveats for all platforms
Release notes are intended to be release-specific for the most current release, and the information provided in these documents may not be cumulative in providing information about features that first appeared in previous releases. Refer to Cisco Feature Navigator for cumulative feature information.
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