Using Cisco IOS XE Software

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.

Table 1. Accessing and Exiting Command Modes

Command Mode

Access Method

Prompt

Exit Method

User EXEC

Log in. 


Router>

Use the logout command.

Privileged EXEC

From user EXEC mode, use the enable EXEC command. 


Router#

To return to user EXEC mode, use the disable command.

Global configuration

From privileged EXEC mode, use the configure terminal privileged EXEC command. 


Router(config)#

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. 


Router(config-if)#

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:

  • In some cases, diagnostic mode will be reached when the IOS process or processes fail. In most scenarios, however, the router will reload.
  • A user-configured access policy was configured using the transport-map command that directed the user into diagnostic mode. See the Console Port, Telnet, and SSH Handling chapter of this book for information on configuring access policies.
  • The router was accessed using a Route Switch Processor auxiliary port.
  • A break signal (Ctrl-C , Ctrl-Shift-6 , or the send break command ) was entered and the router was configured to go into diagnostic mode when the break signal was received. 

Router(diag)#

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


Note
For more information about connecting cables to the router, see the Connecting a Cisco ASR 920 Series Router to the Network section in the Cisco ASR 920 Series Aggregation Services Router Hardware Installation Guide.

Note
For information about installing USB devices drivers in order to use the USB console port, see the Cisco ASR 920 Series Aggregation Services Router Hardware Installation Guide.

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.

Table 2. Keyboard Shortcuts

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

1 The arrow keys function only on ANSI-compatible terminals such as VT100s.

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.

Table 3. 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. 


Router# show  history

While in EXEC mode, list the last several commands you have just entered.

2 The arrow keys function only on ANSI-compatible terminals such as VT100s.

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:

Table 4. Help Commands and Purpose

Command

Purpose 


help

Provides a brief description of the help system in any command mode. 


abbreviated-command-entry
?

Provides a list of commands that begin with a particular character string. (No space between command and question mark.) 


abbreviated-command-entry
<Tab
>

Completes a partial command name. 


?

Lists all commands available for a particular command mode. 


command
 ?

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 

Router> enable
Password: <password>
Router#

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# . 

Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#

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)# . 

Router(config)#  gigabitethernet 0/0/1

Enter interface configuration mode by specifying the serial interface that you want to configure using the gigabitethernet or tengigabitethernet global configuration command. 

Router(config-if)# ?
Interface configuration commands:
.
.
.
ip Interface Internet Protocol config commands
keepalive Enable keepalive
lan-name LAN Name command
llc2 LLC2 Interface Subcommands
load-interval Specify interval for load calculation for an
interface
locaddr-priority Assign a priority group
logging Configure logging for interface
loopback Configure internal loopback on an interface
mac-address Manually set interface MAC address
mls mls router sub/interface commands
mpoa MPOA interface configuration commands
mtu Set the interface Maximum Transmission Unit (MTU)
netbios Use a defined NETBIOS access list or enable
name-caching
no Negate a command or set its defaults
nrzi-encoding Enable use of NRZI encoding
ntp Configure NTP
.
.
.
Router(config-if)#

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. 

Router(config-if)# ip ?
Interface IP configuration subcommands:
access-group Specify access control for packets
accounting Enable IP accounting on this interface
address Set the IP address of an interface
authentication authentication subcommands
bandwidth-percent Set EIGRP bandwidth limit
broadcast-address Set the broadcast address of an interface
cgmp Enable/disable CGMP
directed-broadcast Enable forwarding of directed broadcasts
dvmrp DVMRP interface commands
hello-interval Configures IP-EIGRP hello interval
helper-address Specify a destination address for UDP broadcasts
hold-time Configures IP-EIGRP hold time
.
.
.
Router(config-if)# ip

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. 

Router(config-if)# ip address ?
A.B.C.D IP address negotiated IP Address negotiated over PPP
Router(config-if)# ip address

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. 

Router(config-if)# ip address 172.16.0.1 ?
A.B.C.D IP subnet mask
Router(config-if)# ip address 172.16.0.1

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. 

Router(config-if)# ip address 172.16.0.1 255.255.255.0 ?
secondary Make this IP address a secondary address
<cr>
Router(config-if)# ip address 172.16.0.1 255.255.255.0

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. 

Router(config-if)# ip address 172.16.0.1 255.255.255.0
Router(config-if)#

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-config
Building 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+found
15105  drwx        4096   Feb 2 2000 13:35:07 +05:30  .ssh
45313  drwx        4096  Nov 17 2011 17:36:12 +05:30  core
75521  drwx        4096   Feb 2 2000 13:35:11 +05:30  .prst_sync
90625  drwx        4096   Feb 2 2000 13:35:22 +05:30  .rollback_timer
105729  drwx        8192  Nov 21 2011 22:57:55 +05:30  tracelogs
30209  drwx        4096   Feb 2 2000 13:36:17 +05:30  .installer
1339412480 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+found
15105  drwx        4096   Feb 2 2000 13:35:07 +05:30  .ssh
45313  drwx        4096  Nov 17 2011 17:36:12 +05:30  core
75521  drwx        4096   Feb 2 2000 13:35:11 +05:30  .prst_sync
90625  drwx        4096   Feb 2 2000 13:35:22 +05:30  .rollback_timer
   12  -rw-           0   Feb 2 2000 13:36:03 +05:30  tracelogs.878
105729  drwx        8192  Nov 21 2011 23:02:13 +05:30  tracelogs
30209  drwx        4096   Feb 2 2000 13:36:17 +05:30  .installer
   13  -rw-        1888  Nov 21 2011 23:03:17 +05:30  startup-config
1339412480 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.bin
2  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 []? 172.17.16.81
Destination 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 protocol
FastEthernet0/0 is up, line protocol is up
Serial4/0 is up, line protocol is up
Serial4/1 is up, line protocol is up
Serial4/2 is administratively down, line protocol is down
Serial4/3 is administratively down, line protocol is down

Powering 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# reload
Proceed 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


Warning

You will loose the startup configuration by using this Password Recovery procedure.


Note
The configuration register is usually set to 0x2102 or 0x102. If you can no longer access the router (because of a lost login or TACACS password), you can safely assume that your configuration register is set to 0x2102.

Before you Begin:

Make sure that the hyperterminal has the following settings:

  • 9600 baud rate

  • No parity

  • 8 data bits

  • 1 stop bit

  • No flow control

  • Use the power switch to turn off the router and then turn it on again.

  • 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.

  • Type confreg 0x2142 at the ROMMON. 
    
1> confreg 0x2142 
1>sync

    The router reboots, but ignores the saved configuration.

  • The router will reload and prompt for configuration.Type no after each setup question, or press Ctrl-C to skip the initial setup procedure.

  • Type enable at the Router> prompt.

    You are now in enable mode and should see the Router# prompt.

  • 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.