This article explains how configuration synchronization works between Multinode High Availability (MNHA) nodes on SRX Series and vSRX.

The configuration synchronization in Multinode High Availability is not enabled by default.

In a Multinode High Availability (MNHA) deployment, the two nodes are independent devices that do not share a single configuration database. Configuration synchronization is not enabled by default; when enabled, it is driven by the commit peers-synchronize mechanism, which authenticates to the remote peer over NETCONF/SSH and pushes configuration to it.

Two approaches exist for keeping common configuration consistent between the nodes:

 (1) Manually copy and paste  or script  the common configuration onto both devices; or

 (2) Use synchronized Junos configuration groups that are edited on one device and pushed to the peer on commit.

 Option 2 is the recommended approach and is described below. MNHA nodes synchronize configuration exclusively based on this group method.

When you enable synchronization (using the peers-synchronize option) on both devices, the configuration you enter on one peer under [groups] automatically syncs to the other peer on commit. Synchronization applies only to common configuration carried under [groups].

The following packets, services, and processes remain node-specific (local) and are not synchronized between the nodes:

• Routing protocol packets to the Routing Engine.
• Management services, such as SNMP, and operational commands (show, request).
• Processes such as the authentication service process (authd) integrated with RADIUS and LDAP servers.
• ICL-encryption-specific tunnel control and data packets.

Configuration synchronization is not mandatory for MNHA to function; it is a convenience for maintaining common configuration. If sync is not used, common configuration must be applied manually or via an external tool.

For configuration examples, refer to: 

Configuration Synchronization Between Multinode High Availability Nodes

Configure Multinode High Availability Using Junos Group Statements