Reserve Memory for Console Access

First Published: July, 22, 2002
Last Updated: December 3, 2010

The Reserve Memory for Console Access feature implements command-line interface (CLI) and software enhancements that allow you to reserve sufficient memory to log in to the router console and perform administrative tasks and troubleshooting. These enhancements give administrators the ability to log in to the router in any situation even when the router is running low on memory.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Reserve Memory for Console Access" section.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

•Information About Reserve Memory for Console Access

•How to Configure Reserve Memory for Console Access

•Configuration Examples for Reserve Memory for Console Access

•Additional References

•Feature Information for Reserve Memory for Console Access

Information About Reserve Memory for Console Access

Before you increase the amount of memory reserved for console access, you should understand the following concepts:

•More Reserved Memory for Console Access Benefit

•Guidelines for Increasing Reserved Memory for Console Access

More Reserved Memory for Console Access Benefit

Before the release of Cisco IOS 12.0(22)S software, you could not access the router console if a router was low on memory or was heavily fragmented. To maintain routers at optimum performance levels, you need to be able to access the console and perform troubleshooting when necessary.

With the release of the Reserve Memory for Console Access feature, the benefit is that you can reserve sufficient memory to log in to the router console and perform administrative tasks and troubleshooting in any situation, even when the router is running low on memory or is heavily fragmented.

Guidelines for Increasing Reserved Memory for Console Access

Cisco IOS software reserves a default of 256 kilobyte (KB) of memory for console access. You can increase the reserved memory through the use of the memory reserved console command provided by the Reserve Memory for Console Access feature.

You may need to increase the amount of memory reserved for console access if the router is low on memory or is heavily fragmented. Increasing the memory allows console access to perform troubleshooting or other administrative tasks to maintain routers at optimum performance levels.

The guideline we suggest for using the command is to configure a value greater than three times the number of the used bytes in NVRAM. You can obtain the number of used bytes in NVRAM from the output of the dir nvram: command. For example, if the total number of used bytes of NVRAM displayed in the command dir nvram: output is 129016 bytes, the nearest kilobyte value rounded off is 129 KB. This value multiplied by 3 is 387 KB. Following the guideline, you would enter 387 as the value for the number-of-kilobytes argument in the memory reserved console command. You can increase the reserved memory for console access to a maximum of 4096 KB.

To display the current operational size of the memory reserved for the console, you can use the show memory console reserved command.

How to Configure Reserve Memory for Console Access

To configure reserve memory for console access, complete the task in this section:

SUMMARY STEPS

1. enable

2. configure terminal

3. memory reserve console number-of-kilobytes

4. exit

5. show memory console reserved

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

memory reserved console number-of-kilobytes

Example:

Router(config)# memory reserved console 512

Increases the amount of memory reserved for console access.

•The number-of-kilobytes argument is the amount of memory to be reserved in kilobytes. Valid values are 1 to 4096 KB.

Step 4 

exit

Example:

Router(config)# exit

Exits to privileged EXEC mode.

Step 5 

show memory console reserved

Example:

Router# show memory console reserved

Displays the actual amount of memory that has been reserved.

Examples

The following is sample output from the show memory console reserved command: 

Router# show memory console reserved

 
   
 
    
   
 
    
Memory reserved for console is 201400

 
   
 
     
    
    
   
 Configuration Examples for Reserve Memory for Console Access 
 
    
   
 •Example: Configuring Reserve Memory for Console Access. 
 
     
    
    
   
 Example: Configuring Reserve Memory for Console Access 
 
    
   
 The following example shows how to increase the reserve memory for console access to 1024 KB: 
 
    
   
 
    
enable

 
   
 
    
   
 
    
! 

 
   
 
    
   
 
    
configure terminal

 
   
 
    
   
 
    
!

 
   
 
    
   
 
    
memory reserved console 1024

 
   
 
    
   
 
    
end

 
   
 
    
   
 
    
 
   
 
    
   
 The following example shows how to disable the increase in reserved memory for the console access: 
 
    
   
 
    
enable

 
   
 
    
   
 
    
!

 
   
 
    
   
 
    
configure terminal

 
   
 
    
   
 
    
!

 
   
 
    
   
 
    
no memory reserved console

 
   
 
    
   
 
    
end

 
   
 
    
   
 
    
 
   
 
     
    
    
   
 Additional References 
 
     
    
   
 Related Documents
 
   
 
    
 
      
      
      
 
        
        

          Related Topic 
        
 		 
        
        

          Document Title 
        
 		 
      
 
      
 
       
 Cisco IOS commands 
 		 
       
 Cisco IOS Master Commands List, All Releases 
 		 
      
 
      
 
       
 Cisco IOS configuration commands 
 		 
       
 Cisco IOS Configuration Fundamentals Command Reference 
 		 
      
 
      
 
       
 Cisco IOS Configuration Fundamentals configuration tasks and concepts 
 		 
       
 Cisco IOS Configuration Fundamentals Configuration Guide 
 		 
      
 
      
    
 
   
 
   
 
   
 
 
     
    
   
 Standards
 
   
 
    
 
      
      
      
 
        
        

          Standard 
        
 		 
        
        

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 No new or modified standards are supported, and support for existing standards has not been modified 
 		 
       
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 MIBs
 
   
 
    
 
      
      
      
 
        
        

          MIB 
        
 		 
        
        

          MIBs Link 
        
 		 
      
 
      
 
       
 •No new or modified MIBs are supported, and support for existing MIBs has not been modified. 
 		 
       
 To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL: 
 
 http://www.cisco.com/go/mibs 
 		 
      
 
      
    
 
   
 
   
 
   
 
 
     
    
   
 RFCs
 
   
 
    
 
      
      
      
 
        
        

          RFC 
        
 		 
        
        

          Title 
        
 		 
      
 
      
 
       
 No new or modified RFCs are supported, and support for existing RFCs has not been modified. 
 		 
       
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 Technical Assistance
 
   
 
    
 
      
      
      
 
        
        

          Description 
        
 		 
        
        

          Link 
        
 		 
      
 
      
 
       
 The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. 
 		 
       
 http://www.cisco.com/cisco/web/support/index.html 
 		 
      
 
      
    
 
   
 
   
 
   
 
 
     
    
    
   
 Feature Information for Reserve Memory for Console Access 
 
    
   
 Table 1 lists the release history for this feature. 
 
    
   
 Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation. 
 
    
   
 Cisco IOS software images are specific to a Cisco IOS software release, a feature set, and a platform. Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear. 
 
   
 
     
   
 
   
 
    
   
 Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release. Unless noted otherwise, subsequent maintenance releases of that Cisco IOS software release also support that feature. 
 
   
 
    
   
 
 
   
 
    
 
      
       
       
      
 Table 1 Feature Information for Reserve Memory for Console Access  
 
      
      
      
 
        
        

          Feature Name 
        
 		 
        
        

          Releases 
        
 		 
        
        

          Feature Information 
        
 		 
      
 
      
 
       
 Reserve Memory for Console Access 
 		 
       
 12.0(22)S
12.2(28)SB
12.4(15)T 
 		 
       
 The Reserve Memory for Console Access feature implements command-line interface (CLI) and software enhancements that allow you to reserve sufficient memory to log in to the router console and perform administrative tasks and troubleshooting. These enhancements give administrators the ability to log in to the router in any situation even when the router is running low on memory. 
 
 The following commands were modified by this feature: memory reserved console, show memory console reserved. 
 		 
      
 
      
    
 
   
 
   
 
   
 
 
    
   
 
    
   
 Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R) 
 
    
    
    
   
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