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About Atomic Configuration and Atomic Update—DMI-Compatible Devices
Copyright © 2010, Juniper Networks, Inc.
Updates Without Errors—If the device executes the entire modeled configuration
(all commands) and the connection to the management system remains up or
can be reestablished, NSM unlocks the active configuration and saves the new
active configuration. The device sends a final message to the management system;
this message appears in the Job Manager status window for this update.
Updates With Errors—If the device cannot execute a command, it notifies the
management system, which makes a decision whether to ignore and proceed,
abort, or revert.
For ignore and proceed decisions, the device continues the update.
For abort and revert decisions, the device automatically resets. The device unlocks
the active configuration and restores the saved active configuration (the device
reboots). After rebooting, the device sends a final error message to the
management system; this message, which includes any CLI errors in the failed
configuration, appears in the Job Manager status window for this update.
Re-establish Management Connection—If the device connection to the
management system is down after all commands have been executed, the device
attempts to reestablish connectivity.
If successful, NSM unlocks the active configuration and restores the saved active
configuration to the device. The device sends a final message to the management
system; this message appears in the Job Manager status window for this update.
If attempts to reconnect are unsuccessful for two hours, the update timer expires
and the device automatically resets. The device unlocks the active configuration
and restores the saved active configuration (the device reboots). After rebooting
and reestablishing the connection to the management system, the device sends
a final error message to the management system; this message, which includes
any CLI errors in the failed configuration, appears in the Job Manager status window
for this update.
The device management interface (DMI) provides built-in support for atomic configuration
and atomic update for JUNOS devices, Secure Access devices, and Infranet Controller
devices. The update to the device does not get committed until the operation is complete,
so a failure during an Update Device operation can never leave an inconsistent
configuration on the device.
If the Update Device directive finishes and the connection between the device and
NSM remains up, the device transitions to use the new configuration. The Update
Device operation is successful.
If the connection between the device and NSM is lost during the Update Device
operation, the job status will report failure, and the device will rollback to the original
configuration. Unlike ScreenOS devices, however, DMI-compatible devices do not need
to reboot in order to rollback.
If the connection between the device and NSM remains up throughout the Update
Device operation, but the update itself fails, the DMI device will keep the original
Chapter 6: Updating Devices
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