Description

This article describes the configuration modes available on Junos.

Solution

 Junos Configuration Process

  1. Edit candidate configuration.
  2. Commit changes to candidate.
  3. Configuration is in effect.

Junos Configuration Modes: Batch, Dynamic, Exclusive, Private, Standard (Shared)

user@host> configure ?
Possible completions:
  <[Enter]>            Execute this command
  batch                Work in batch mode (commit happens in batch)
  dynamic              Work in dynamic database
  exclusive            Obtain exclusive lock (other users cannot make changes)
  private              Work in private database (other's changes do not show)
  |                    Pipe through a command
 

Batch

  • Currently supported on MX Series 3D Universal Edge Router running 12.1 or later Junos.

  • Junos OS provides a batch commit feature that aggregates or merges multiple configuration edits from different CLI sessions or users and adds them to a batch commit queue. A batch commit server running on the device takes one or more jobs from the batch commit queue, applies the configuration changes to the shared configuration database, then commits the configuration changes in a single commit operation.

  • Good:

    • When compared to the regular commit operation (in which all commits are independently committed sequentially), batch commits save time and system resources by committing multiple small configuration edits in a single commit operation.


Dynamic

  • Used for systems that have thousands of lines of policies configured.

  • BGP is the only protocol to which you can apply routing policies that reference policies and policy objects configured in the dynamic database.

  • Good:

    • Policies configured in a dynamic database are not subject to the strenuous checking performed during a commit. This can save much time, especially when the configuration includes thousands of lines.

  • Not So Good:

    • If used without caution, it can cause network disruption.


Exclusive
Exclusive access to the candidate configuration.

  • Good:

    • It guarantees that only one at a time user will modify, commit, or roll back the router configuration.

    • It can be used to block the configuration for other users during critical changes (for example, in loopback filters, IGP routing changes, MPLS, RSVP, and LDP configurations).

  • Not So Good:

    • Only one user at a time can enter in configuration mode.


Private
Different candidate configuration for each user.

  • Good:

    • Allows each user to work in his or her own copy of the candidate configuration.

    • The commit and rollback procedures of one user do not affect the configuration of another user.

    • It is the safest configuration mode.

  • Not So Good:

    • It does not allow the use of commit confirmed except for SRX.
       

Standard (Shared)
Unique candidate configuration for all users.

  • Good:

    • Allows the user to perform commit confirmed.

    • All users can see the changes being made in the candidate configuration.

  • Not So Good:

    • The commit process of one user will commit the changes of all users who are configuring the router at the same time. <<< <This can be very dangerous.

    • Uncommitted changes can remain in the candidate configuration until the next commit or rollback 0. <<< <This can also be dangerous.

    • The show | compare will show not only the user changes, but also the changes that all users made until that moment.

    • The rollback procedure will roll back the configuration of all users.

 

Modification History

2022-09-12: Minor edits.
2020-06-23: Article reviewed for accuracy; no changes required.
2018-02-08: added note regarding SRX supporting commit confirmed in private mode.
 

Related Information