Juniper QFX3500 - Backup Routing Engine Role; Linecard Role

In a mixed QFX Series Virtual Chassis made up of QFX5100 switches with QFX3500,
QFX3600, or EX4300 switches, we recommend configuring QFX5100 switches into the
Routing Engine role. If the mixed Virtual Chassis does not contain QFX5100 switches, we
recommend configuring QFX3500 or QFX3600 switches into the Routing Engine role.
Backup Routing Engine Role
The member that functions in the backup Routing Engine role in a Virtual Chassis:
•
Maintains a state of readiness to take over the master Routing Engine role if the master
fails.
•
Runs Junos OS for the switches as a backup Routing Engine.
•
Synchronizes with the master in terms of protocol states, forwarding tables, and other
information, so that it is prepared to preserve routing information and maintain network
connectivity without disruption in case the master is unavailable.
You must have at least two member switches in the Virtual Chassis configuration in order
to have a backup Routing Engine member.
In a preprovisioned configuration, one of the two members assigned as routing-engine
functions in the backup role. The selection of which member assigned as routing-engine
functions as master and which as backup is determined by the software based on the
master election algorithm. See Understanding How the Master in a Virtual Chassis Is
Elected.
In a configuration that is not preprovisioned, the selection of the master and backup is
determined by the mastership priority value and secondary factors in the master election
algorithm.
In a QFX5110 Virtual Chassis with QFX5110 and QFX5100 switches, we recommend
configuring only QFX5110 switches into the Routing Engine role.
In a mixed QFX Series Virtual Chassis made up of QFX5100 switches with QFX3500,
QFX3600, or EX4300 switches, we recommend configuring the QFX5100 switches into
the Routing Engine role. If the mixed Virtual Chassis does not contain QFX5100 switches,
we recommend configuring QFX3500 or QFX3600 switches into the Routing Engine role.
Linecard Role
A member that functions in the linecard role in a Virtual Chassis:
•
Runs only a subset of Junos OS.
•
Does not run the chassis control protocols.
•
Can detect certain error conditions (such as an unplugged cable) on any interfaces
that have been configured on it through the master.
The Virtual Chassis configuration must have at least three members in order to include
a linecard member.
Copyright © 2017, Juniper Networks, Inc.14
QFX3500 Device Hardware Documentation