Information About Configuration Partitioning
System Running Configurations
Managing the configuration of any Cisco IOS software-based device involves managing the startup configuration (startup-config), which is a file stored in nonvolatile memory, and the running configuration (running-config), which is the set of all configuration options currently in effect on the system. Typically, the startup configuration file is loaded when the system boots, and changes to the system’s running configuration, applied using the command-line interface (CLI), are saved by copying the running configuration to a configuration file (either locally or on the network), which can then be used to configure the device at startup, or used to configure other devices.
Retrieving the Running Configuration for Display or Copy Operations
In the Cisco IOS software configuration model, the configuration state is maintained in a distributed manner, with each component storing its own configuration state. To retrieve global configuration information, the software must poll every component to collect the distributed information. This configuration state retrieval operation is performed by a process known as nonvolatile generation (NVGEN), and it is invoked by commands such as showrunning-config , which is used to display the current configuration state, and copysystem:running-configuration , which is used to save the running configuration by copying it to a file. When invoked, the NVGEN process queries each system component, each interface instance, and all other configured component objects in a standard sequence. A running configuration file is constructed as NVGEN traverses the system performing these queries, and it is this “virtual file” that is displayed or copied.
Benefits of Partitioning the Running Configuration
The Configuration Partitioning feature is the latest in a series of Configuration Generation Performance Enhancement Features for Cisco IOS software. (See the “Related Documents” section for related features.) This feature improves the system’s response time by providing a method for querying only the system component you wish to review when issuing the showrunning-config command.
When the Configuration Partitioning feature is enabled, the system groups the configuration state of the device into parts (called “partitions”) for the purpose of generating the virtual running configuration file (the list of configuration commands). A new command, showrunning-configpartition , allows you to display only the part of the running configuration that you want to examine, rather than having to display the entire running configuration at once, or displaying only lines that match a certain string.
The key benefit of this feature is that it increases system performance by allowing the system to run the NVGEN process for only the collection of system components (such as specific interfaces) that you need to display. This is in contrast to other existing extensions to the showrunning-config command, which only filter the generated list after all system components have been processed.
The selective processing of the system’s configuration state for the purpose of generating a partial running configuration is called “configuration partitioning.”
More granular access to configuration information offers important performance benefits for high-end routing platforms with very large configuration files, while also enhancing configuration management by allowing advanced configuration features to be implemented at a more granular level. Advanced configuration options include Cisco IOS software support for provisioning of customer services, Config Rollback, Config Locking, and configuration access control.