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mastership-priority

 

Syntax

Hierarchy Level

Release Information

Statement introduced in Junos OS Release 9.0 for EX Series switches.

Mastership priority option 0 introduced in Junos OS Release 11.1 for EX Series switches.

Statement introduced in Junos OS Release 13.2X50-D15 for the QFX Series.

Statement introduced in Junos OS Release 13.2X51-D20 for Virtual Chassis Fabric (VCF).

Description

Assign a mastership priority value to a member of a Virtual Chassis or VCF. The mastership priority is the most important factor that determines which member assumes the master Routing Engine role in the Virtual Chassis or VCF.

A Virtual Chassis or VCF configuration has two member switches running in the Routing Engine role, one as the master and one as the backup. The remaining members operate in the linecard role. In a preprovisioned Virtual Chassis or VCF, you configure the role for each member by associating it with the member switch’s serial number, and the Virtual Chassis assigns default mastership priorities based on the assigned role. In a non-provisioned Virtual Chassis or VCF, you can configure roles explicitly, or the mastership priorities of the members implicitly designate the role of each member based on the mastership election algorithm.

The Virtual Chassis or VCF elects the member switch with the highest mastership priority as the master Routing Engine. When two members have the same highest mastership priority value among all the members, the master election algorithm uses other factors to determine which of the two members functions as the master and which is the backup. See Understanding How the Master in a Virtual Chassis Is Elected for all the conditions considered in mastership election.

You should assign the same (highest) mastership priority value to the members you want to be the master and backup Routing Engine members to ensure reliable graceful Routing Engine switchover (GRES) operation. This and other mastership election considerations also help keep mastership from switching back and forth rapidly between the two members under failover conditions.

This statement is not used for the EX8200 Virtual Chassis, which determines mastership by external Routing Engine uptime.

A switch with a mastership priority of 0 never takes the master or backup role.

Default

128

Options

number—Mastership priority value.

Range: 0 through 255

Required Privilege Level

system—To view this statement in the configuration.

system-control—To add this statement to the configuration.