Switch SSB Mastership

Purpose

To change the default master SSB, include the ssb statement at the [edit chassis redundancy] hierarchy level in the configuration. For more information, see the JUNOS System Basics Configuration Guide.

Action

To control which SSB is master, use the following CLI command:

user@host> request chassis ssb master switch <no-confirm>

Sample Output

user@host> request chassis ssb master switch

warning: Traffic will be interrupted while the PFE is re-initialized

Toggle mastership between system switch boards ? [yes,no] (no) yes

Switch initiated, use "show chassis ssb" to verify

If you use the no-confirm option, the command output is as follows:

user@host> request chassis ssb master switch no-confirm

Switch initiated, use "show chassis ssb" to verify

What It Means

By default, the SSB in slot 0 (SSB0) is the master and the SSB in slot 1 (SSB1) is the backup.

NOTE: For routers that have two SSBs, both SSBs must be running JUNOS Release 4.0 or later. Do not run JUNOS Release 3.4 on one of the SSBs and JUNOS Release 4.0 or later on the other. JUNOS Release 3.4 does not support SSB redundancy; if you are using this release of the software, only one SSB can be installed in the router. It can be installed in either slot. The configurations on the two SSBs do not have to be the same, and they are not automatically synchronized. If you configure both SSBs as masters, when the chassis software restarts for any reason, the SSB in slot 0 becomes the master and the SSB in slot 1 becomes the backup.