Configuration Sessions overview

The configure session command creates a configuration session for CLI commands and ends it after issuing the commit command. Each configure session has a unique name. You can enter, modify, and exit the session anytime without impacting the currently running system configuration.

While in the commit stage of a session, the running-config command creates copies of the modified configuration of the session, overwriting any other configuration changes made since creating the session. A session can be aborted or removed, which removes the session completely and frees up memory used by the session. You must explicitly request the changes in a deferred session to the switch configuration by entering a commit command and exiting the mode. Alternatively, abandon the changes by entering an abort command. The switch discards an uncommitted configuration session if the switch reboots and the session times out after 24 hours.

Configuration sessions implement the changes after verifying that no configuration errors occur. Configuration sessions allow the administrator to pre-provision a group of CLI commands in a named session and execute each configuration session at specified times.

Note: Committing a configuration session replaces the running-config with the session configuration which includes the running configuration at the initial session and the commands entered as part of the session. Any changes made to running-config since the initiation of the session overwrite the session during the commit stage.

Configuration Session

The configure session command allows you to execute a series of configuration changes in a temporary location and commit them to running-config by issuing the commit command.

configure session <name of session> and running-config: The user enters a session (versus configure terminal where configuration sessions are not used). It creates a system-named session if a session name is not specified, and it copies a snapshot of the current running-config into the session’s data structure as the basis of further configuration changes.
CLI configuration commands - The user can run any commands inside the session.
rollback clean-config - The user can run the rollback command to revert the session configuration to the factory-default configuration (or clean configuration).
show session-config - The user can run show session-config to show the session configuration, which will be the future running-config after committing.
commit - Issuesthe commit command to commit the changes and replace the current running-config.
abort - Abort the session and discard all changes.
exit - exit from the session and return to the same session by running the configure session again.
For a named session, more than one CLI instance can enter the same session and change the session configuration. After the session commits in any of the CLIs, no other CLI can commit or make any other changes in that session.

Note: Committing a configuration session replaces running-config with the session configuration, which consists of the running configuration at the initial session and the commands entered as part of the session. Any changes made to running-config since the initiation of the session overwrite when the session is in the commit stage.

Replacing the Configuration

The command configure replace URL replaces the current running-config with the configuration saved in a URL. By default, the configuration in the configure replace URL replaces running-config only if the configuration in the URL loads without errors. The command configure replace URL ignore-errors force the operation even if there are errors.

Note: The command copy URL running-config applies a saved configuration file to the system and appends that configuration to the current running-config instead of replacing it. However, Arista recommends using the command configure replace URL to streamline the process of restoring the system to a known good configuration.

The normal workflow uses a configuration session to perform the configure replace.

Configuration CLI

In the CLI, execute the following configuration steps to create a configuration session.

configure session [name of session]
Create or enter a session. If a name is not specified, it automatically generates. The user is in the session configuration mode, and the prompt will change to show the first six characters of the session name. Designating the name of a session is optional. When the name of session is not specified, a unique name is assigned.
```
no configure session  name of session 
```
Delete the specified configuration session. Designating the name of a session is required.
commit
Commit the changes made in the session. Configuration mode issues this command within the session.
```
abort
```
Abort the session, which is the same as deleting it. Configuration mode issues this command within the session.
rollback clean-config
Revert the configuration in the session to the clean, factory-default configuration. Configuration mode issues this command within the session.
service configuration session max completed number
Sets a limit on the maximum number of saved committed sessions.
service configuration session max pending number
Sets a limit on the maximum number of uncommitted sessions that can be outstanding.

Using Service Commands in eos

In Arista eos, service commands act as global master switches. Unlike standard interface or routing commands that define what the network should do, service commands interact directly with the underlying Linux kernel and system manager (Sysdb) to dictate how the switch operates under the hood. They control daemon architecture, hardware resource allocation, and how the command-line parser interprets syntax. The commands control the following areas in eos:

Routing and Control Plane Architecture - The

service
                            routing

commands dictate how the switch processes complex routing and handles control-plane memory.


Command	Function
service routing protocols model multi-agent	Shifts the switch from a legacy monolithic routing process (`ribd`) to Arista’s decoupled, high-scale "ArBGP" architecture.
service routing configuration bgp no-equals-default	Scrubs default configuration commands from the running configuration to keep the CLI output clean.
service routing configuration route-map no-set-community explicit members	Allows you to surgically remove a single BGP community from a list in a route-map, rather than forcing the rewrite of the entire line.

Configuration Management and Change Control - The

service
                            configuration

commands manage the interactions between an administrator and the switch as well as manage rolling back configurations.


Command	Function
service configuration terminal disabled	Disables standard live configuration. Forces all users and scripts to use `configure session` to stage and review changes before committing them.
service configuration session max pending `number`	Limits how many uncommitted staging workspaces can be open concurrently.
service configuration session max completed `number`	Defines how deep the historical archive goes for saving successfully committed sessions and their exact CLI diffs.
service configuration checkpoint max `number`	Adjusts the retention limit for full-system configuration snapshots.

Hardware and Interface Management - The

service
                        interface

commands interact directly with the physical ASICs, port allocation, and optical transceivers on the switch.


Command	Function
service interface inactive port-id allocation disabled	Reclaims hardware resources on high-density modular chassis by preventing the switch from assigning internal Port IDs to physically down or unprovisioned interfaces.
service interface shutdown default	Changes the factory default behavior so that all unconfigured ports are placed in an administratively down state.
service interface shutdown delay `seconds`	Introduces a physical hardware buffer between typing `shutdown` and the port actually dropping, allowing routing protocols to gracefully reroute traffic.

EOS 4.36.2F User Manual

Configuration Sessions overview

Configuration Session

Replacing the Configuration

Configuration CLI

Using Service Commands in eos