Global Roles And Local Roles That Determine Mastership And Switchover; Behavior; Mastership Election In A Virtual Chassis - Juniper EX9200 Features Manual

CHAPTER 7
Global Roles and Local Roles that
Determine Mastership and Switchover

Behavior

Mastership Election in a Virtual Chassis

Copyright © 2017, Juniper Networks, Inc.
Mastership Election in a Virtual Chassis on page 57
Global Roles and Local Roles in a Virtual Chassis on page 59
Switching the Global Master and Backup Roles in a Virtual Chassis
Configuration on page 61
In a two-member MX Series or EX9200 Virtual Chassis, either member device can be
elected as the master device (also known as the protocol master, or VC-M) of the Virtual
Chassis. The first member device to join the Virtual Chassis becomes the initial master
device by default. After the Virtual Chassis is formed with both member devices, the
Virtual Chassis Control Protocol (VCCP) software runs a mastership election algorithm
to elect the master device for the Virtual Chassis configuration.
If the master device in a Virtual Chassis fails, the backup device (also known as the
protocol backup, or VC-B) takes over mastership of the Virtual Chassis. You can also
switch the global roles of the master device and backup device in a Virtual Chassis by
issuing the
request virtual-chassis routing-engine master switch
NOTE: You cannot configure mastership election for an MX Series or EX9200
Virtual Chassis in the current release.
The VCCP software uses the following algorithm to elect the master device for an EX9200
or MX Series Virtual Chassis:
Choose the member device that has the highest value for the internal mastership
1.
election flag.
The mastership election algorithm uses an internal flag that keeps track of the member
state for the purpose of electing the Virtual Chassis master device. In most cases,
VCCP elects the member device with the higher flag value over the member device
with the lower flag value as the protocol master.
command.
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