- Managing Configuration Files
- Configuration Generation Performance Enhancement
- Exclusive Configuration Change Access and Access Session Locking
- Configuration Replace and Configuration Rollback
- Contextual Configuration Diff Utility
- Configuration Change Notification and Logging
- Configuration Logger Persistency
- Finding Feature Information
- Information About Locking the Configuration
- How to Configure Configuration Exclusive Confguration Change-Access and Access Session Locking
- Configuration Examples for Locking the Configuration
- Additional References
- Feature Information for Exclusive Configuration Change Access and Access Session Locking
Exclusive Configuration Change Access and Access Session Locking
Exclusive Configuration Change Access (also called the “Configuration Lock” feature) allows you to have exclusive change access to the Cisco IOS XE running configuration, preventing multiple users from making concurrent configuration changes.
The Access Session Locking addition to this feature extends the Exclusive Configuration Change Access feature such that show and debug commands entered by the user holding the configuration lock always have execution priority; show and debug commands entered by other users are only allowed to run after the processes initiated by the configuration lock owner have finished.
The Exclusive Configuration Change Access feature (“exposed lock”) is complementary with the locking mechanism in the Configuration Replace and Configuration Rollback feature (“rollback lock”).
- Finding Feature Information
- Information About Locking the Configuration
- How to Configure Configuration Exclusive Confguration Change-Access and Access Session Locking
- Configuration Examples for Locking the Configuration
- Additional References
- Feature Information for Exclusive Configuration Change Access and Access Session Locking
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and 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 table.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Information About Locking the Configuration
- Exclusive Configuration Change Access and Access Session Locking
- Access Session Locking
- Parser Concurrency and Locking Improvements
Exclusive Configuration Change Access and Access Session Locking
Devices running Cisco IOS software maintain a running configuration that determines the configuration state of the device. Changes to the running configuration alter the behavior of the device. Because Cisco IOS software allows multiple users to change the running configuration via the device CLI (including the device console and telnet Secure Shell (SSH)), in some operating environments it would be beneficial to prevent multiple users from making concurrent changes to the Cisco IOS running configuration. Temporarily limiting access to the Cisco IOS running configuration prevents inadvertent conflicts or cases where two users attempt to configure the same portion of the running configuration.
The Exclusive Configuration Change Access feature (also called the “Configuration Lock” feature) allows you to have exclusive change access to the Cisco IOS running configuration, preventing multiple users from making concurrent configuration changes.
This feature provides exclusive change access to the Cisco IOS running configuration from the time you enter global configuration mode by using the configure terminal command. This gives the effect of a “configuration lock,” preventing other users from changing the Cisco IOS running configuration. The configuration lock is automatically released when the user exits Cisco IOS configuration mode.
The Exclusive Configuration Change Access feature is enabled using the configuration mode exclusive command in global configuration mode. Exclusive configuration change access can be set to auto, so that the Cisco IOS configuration mode is locked whenever anyone uses the configure terminal command, or it can be set to manual, so that the Cisco IOS configuration mode is locked only when the configure terminal lock command is issued.
The Exclusive Configuration Change Access feature is complementary with the locking mechanism for the Configuration Replace and Configuration Rollback feature introduced in Cisco IOS Release 12.2(25)S and 12.3(7)T.
Access Session Locking
The Access Session Locking feature extends the Exclusive Configuration Change Access feature such that show and debug commands entered by the user holding the configuration lock always have execution priority. This feature prevents concurrent configuration access and also provides an option to prevent simultaneous processes, such as a show command entered by another user, from executing while other configuration commands are being executed. When this feature is enabled, the commands entered by the user with the configuration lock (such as configuration commands) always have priority over commands entered by other users.
Parser Concurrency and Locking Improvements
In order to overcome the following limitations posed by the Exclusive Configuration Change Access feature, the Parser Concurrency and Locking Improvements feature was introduced in Cisco IOS Release 12.2(33)SRE:
The Exclusive Configuration Change Access feature locks the configuration to other users. The lock is automatically released when the lock holder exits from the configuration mode. Any other user in the configuration mode will be returned to the EXEC mode when the lock is acquired. Also, any user can execute the clearconfigurationlock command and forcibly remove the lock and allow normal access to all users.
The router can reload when multiple write processes belonging to the same client simultaneously access the Cisco IOS configurations in a shared mode.
The router can reload when EXEC commands concurrently access the data structure.
Effective from Cisco IOS Release 12.2(33)SRE, the Concurrency and Locking Improvements feature is the primary locking mechanism used to prevent concurrent configuration of Cisco IOS software by multiple users.
The Parser Concurrency and Locking Improvements feature provides a common interface that ensures that exclusive access is granted to the requested process and prevents others from concurrently accessing the Cisco IOS configuration. It allows access only to the user holding the lock and prevents other clients from accessing the configuration.
Effective from Cisco IOS Release 12.2(33)SRE, the configurationmodeexclusive {auto | manual} command will not be available to enable single-user access functionality for the Cisco IOS CLI. Use the parsercommandserializer command to enable configuration access only to the users holding the lock and prevent other clients from accessing the configuration.
How to Configure Configuration Exclusive Confguration Change-Access and Access Session Locking
- Enabling Exclusive Configuration Change Access and Access Session Locking
- Obtaining Exclusive Configuration Change Access
- Enabling Parser Concurrency and Locking Improvements
- Monitoring and Troubleshooting Configuration Locking
Enabling Exclusive Configuration Change Access and Access Session Locking
Note | Effective with Cisco IOS Release 12.2(33)SRE, the Exclusive Configuration Change Access and Access Session Locking feature is not available in Cisco IOS software. Use the Parser Concurrency and Locking Improvements feature instead of this feature. See the “Enabling Parser Concurrency and Locking Improvements” section for more information. |
1.
enable
2.
configure
terminal
3.
configuration
mode
exclusive
4.
end
DETAILED STEPS
Obtaining Exclusive Configuration Change Access
1.
enable
2.
configure
terminal
3.
configure
terminal
lock
4. Configure the system by entering your changes to the running configuration.
DETAILED STEPS
Enabling Parser Concurrency and Locking Improvements
Perform this task to enable configuration access only to the users holding a configuration lock and to prevent other clients from accessing the running configuration.
Note | The Parser Cconcurrency and Locking Improvements feature does not allow two or more processes to exist simultaneously within the critical section of Cisco IOS configurations. This feature flags a command to prevent its serialization if an excessive amount of time is required to generate its output or if its use produces more than 10 kilobytes of output. Examples of commands that would not be serialized are the showterminal and showrunning-config commands. |
1.
enable
2.
configure
terminal
3.
parser
command
serializer
4.
exit
DETAILED STEPS
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable
Example: Router> enable |
Enables privileged EXEC mode.
|
Step 2 |
configure
terminal
Example: Router# configure terminal |
Enters global configuration mode. |
Step 3 |
parser
command
serializer
Example: Router(config)# parser command serializer |
Introduces an exclusive lock to serialize access to Cisco IOS configurations. |
Step 4 |
exit
Example: Router(config)# exit |
(Optional) Exits global configuration mode. |
Monitoring and Troubleshooting Configuration Locking
Perform either or both steps in this task to monitor or troubleshoot the Exclusive Configuration Change Access and Access Session Locking feature.
1.
show
configuration
lock
2.
debug
configuration
lock
DETAILED STEPS
Step 1 |
show
configuration
lock
Use this command to display the status and details of any current configuration locks, including the owner, user, terminal, lock state, and lock class. If you cannot enter global configuration mode, you can use this command to determine if the configuration session is locked by another user, and who that user is. Example:
|
Step 2 |
debug
configuration
lock
Use this command to enable debugging of Cisco IOS configuration locks (exposed class locks or rollback class locks): Example: Router# debug configuration lock Session1 from console ========================== Router# configure terminal lock Configuration mode locked exclusively. The lock will be cleared once you exit out of configuration mode using end/exit Enter configuration commands, one per line. End with CNTL/Z. Router(config)# Parser : LOCK REQUEST in EXCLUSIVE mode Parser: <configure terminal lock> - Config. Lock requested by process <3> client <PARSER Client> Parser: <configure terminal lock> - Config. Lock acquired successfully ! Router(config)# |
Configuration Examples for Locking the Configuration
- Configuring an Exclusive Lock in Auto Mode Example
- Configuring an Exclusive Lock in Manual Mode Example
- Configuring Parser Concurrency and Locking Improvements Example
Configuring an Exclusive Lock in Auto Mode Example
The following example shows how to enable the exclusive lock in auto mode for single-user auto configuration mode using the configurationmodeexclusive command. Once the Cisco IOS configuration file is locked exclusively, you can verify this configuration by using the showconfigurationlockcommand.
Router# configure terminal Router(config)# Router(config)# exit Router# configure terminal ! Locks configuration mode exclusively. Router# show configuration lock Parser Configure Lock Owner PID : 10 User : User1 TTY : 3 Type : EXCLUSIVE State : LOCKED Class : Exposed Count : 0 Pending Requests : 0 User debug info : 0
Configuring an Exclusive Lock in Manual Mode Example
Configuring Parser Concurrency and Locking Improvements Example
The following example shows how to enable the Parser Concurrency and Locking Improvements feature by using the parsercommandserializer command:
Router# configure terminal Router(config)# parser command serializer Router(config)# exit
Additional References
The following sections provide references related to locking the configuration.
Related Documents
Related Topic |
Document Title |
---|---|
Commands for managing configuration files |
Cisco IOS Configuration Management Command Reference |
Information about managing configuration files |
Managing Configuration Files |
Standards
Standard |
Title |
---|---|
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
-- |
MIBs
MIB |
MIBs Link |
---|---|
No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature. |
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
RFCs
RFC |
Title |
---|---|
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
-- |
Technical Assistance
Description |
Link |
---|---|
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
Feature Information for Exclusive Configuration Change Access and Access Session Locking
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to . An account on Cisco.com is not required.
Feature Name |
Releases |
Feature Information |
---|---|---|
Exclusive Configuration Change Access and Access Session Locking |
12.3(14)T 12.0(31)S 12.2(33)SRA 12.4(11)T 12.2(33)SXH 12.2(33)SB |
The Exclusive Configuration Change Access feature (also called the “Configuration Lock” feature) allows you to have exclusive change access to the Cisco IOS running configuration, preventing multiple users from making concurrent configuration changes. The Access Session Locking addition to this feature extends the Exclusive Configuration Change Access feature such that show and debug commands entered by the user holding the configuration lock always have execution priority;show and debug commands entered by other users are allowed to run only after the processes initiated by the configuration lock owner have finished. The Exclusive Configuration Change Access feature is complementary with the locking mechanism for the Configuration Replace and Configuration Rollback feature (“rollback lock”). The Configuration Lock feature feature was integrated into Release 12.0S, and the Access Session Locking feature extension was implemented. The configuration mode exclusivecommand was extended to include the following keyword options: config_wait, expire, interleave, lock-show, retry_wait, and terminate. The output of the show configuration lockcommand was improved. The extended feature was integrated into Releases 12.2(33)SRA, 12.4(11)T, 12.2(33)SXH, and 12.2(33)SB. The following sections provide information about this feature: The following commands were introduced or modified: clear configuration lock, configuration mode exclusive, and configure terminal lock. |
Parser Concurrency and Locking Improvements |
12.2(33)SRE 15.1(1)T |
The Parser Concurrency and Locking Improvements feature provides a common interface that ensures that exclusive access is granted to the requested process and prevents others from concurrently accessing the Cisco IOS configuration. It allows access only to the user holding the lock and prevents other clients from accessing the configuration. The following sections provide information about this feature: The following commands were introduced or modified: parser command serializer and test parser session-lock. |