Commit command fails on SRX chassis cluster with dual Router Engines (RE) on each node. This article explains why commit fails, what is the cause and how the issue can be resolved.

Commit command fails on SRX chassis cluster with dual Router Engines (RE) on each node.

On an SRX cluster, setting up the command set system commit synchronize may cause the commit process to fail. This command is used to synchronize the configuration between two routing engines on the same node in a cluster, but in an  SRX cluster, the second RE is used for second control link. This second routing engine boots up in a single user mode, i.e. it does not boot completely.  As a result, the commit script cannot sync the configuration to the second routing engine, thus the entire commit  script fails.

The command set system commit synchronize is for Juniper Networks switches and routers which have dual routing engines as active/backup, and in which both routing engines boot up completely to operate. SRX switches do not have routing engine redundancy within the same node,  i.e.,  only one routing engine (RE0) is always active in an node.

After committing the configuration, the command commit | display detail will display the following messages. Note that in these messages, the commit script is not recognizing any changes.

root@01# commit | display detail
node0:
2013-07-31 12:32:25 CEST: merging latest committed configuration
2013-07-31 12:32:25 CEST: start loading commit script changes
2013-07-31 12:32:26 CEST: no commit script changes
2013-07-31 12:32:26 CEST: no transient commit script changes
2013-07-31 12:32:26 CEST: finished loading commit script changes
2013-07-31 12:32:26 CEST: copying juniper.db to juniper.data+
2013-07-31 12:32:26 CEST: finished copying juniper.db to juniper.data+
2013-07-31 12:32:26 CEST: exporting juniper.conf
2013-07-31 12:32:26 CEST: Exporting /config/juniper.conf.spu

Exiting from the configuration mode here would cause the configuration changes to be lost.

In order to recover, delete the commit synchronize command from the system hierarchy, i.e.,   delete system commit synchronize.  After that, the SRX will be able to commit the configurations as expected.