Juniper JUNOS OS 10.4 - FOR EX REV 1 Manual page 1017

Merging EX4200 Virtual Chassis Configurations
Copyright © 2010, Juniper Networks, Inc.
Chapter 37: EX4200 Virtual Chassis—Overview, Components, and Configurations
It contains the stable master and the configuration is greater than half the Virtual
Chassis size.
It contains the stable backup and is at least half the Virtual Chassis size.
In accordance with the rules given in the second and third list items, if the Virtual Chassis
configuration splits into two equal parts and the stable master and stable backup are in
different parts, then the part that contains the stable backup becomes active.
NOTE: The number of members in the Virtual Chassis configuration includes
all member switches connected to date minus the number whose Virtual
Chassis member IDs have been recycled (that is, made available for
reassignment). Therefore, the size of the Virtual Chassis configuration
increases when a new member switch is detected and decreases when a
member switch's ID is recycled.
These rules ensure that only one of the two separate Virtual Chassis configurations
created by the split remains active. The member switches in the inactive Virtual Chassis
configuration remain in a linecard role. For the inactive members to become active again,
one of the following things must happen:
The problem that caused the original Virtual Chassis configuration to split is resolved,
allowing the two Virtual Chassis configurations to merge.
You load the factory default configuration on the inactive members, which causes the
inactive members to function as standalone switches or become part of a different
Virtual Chassis configuration.
NOTE: When you remove a member switch from a Virtual Chassis
configuration, we recommend that you recycle the member ID using the
request virtual-chassis recycle
There are two scenarios in which separate EX4200 Virtual Chassis merge:
A Virtual Chassis configuration that had split into two is now merging back into a single
configuration because the problem that had caused it to split has been resolved.
You want to merge two Virtual Chassis that had not previously been configured together.
Every Virtual Chassis configuration has a unique ID that is automatically assigned when
the Virtual Chassis configuration is formed. You can also explicitly assign a Virtual Chassis
ID using the set virtual-chassis id
precedence over automatically assigned Virtual Chassis IDs.
When you reconnect the separate Virtual Chassis configurations or connect them for the
first time, the members determine whether or not the separate Virtual Chassis
command.
command. A Virtual Chassis ID that you assign takes
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