Understanding Split And Merge In A Virtual Chassis Configuration - Dell PowerConnect J-EX4200-24T Software Manual

Dell PowerConnect J-Series Ethernet Switch Complete Software Guide for Junos OS
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Understanding Split and Merge in a Virtual Chassis Configuration

What Happens When a Virtual Chassis Configuration Splits
712
Understanding Virtual Chassis Configuration on page 704
Example: Configuring Fast Failover on Uplink Module VCPs to Reroute Traffic When a
Virtual Chassis Member Switch or Intermember Link Fails on page 763
Setting an Uplink Module Port as a Virtual Chassis Port (CLI Procedure) on page 792
In a Virtual Chassis configuration, two or more J-EX4200 Ethernet Switches are connected
together to form a unit that is managed as a single chassis. If there is a disruption to the
Virtual Chassis configuration due to member switches failing or being removed from the
configuration, the Virtual Chassis configuration splits into two separate Virtual Chassis.
This situation could cause disruptions in the network if the two separate configurations
share common resources, such as global IP addresses. The split and merge feature
provides a method to prevent the separate Virtual Chassis configurations from adversely
affecting the network and also allows the two parts to merge back into a single Virtual
Chassis configuration.
NOTE: If a Virtual Chassis configuration splits into separate parts, we
recommend that you resolve the problem that caused the Virtual Chassis
configuration to split as soon as possible.
You can also use this feature to merge two active but separate Virtual Chassis that have
not previously been part of the same configuration into one Virtual Chassis configuration.
NOTE: The split and merge feature is enabled by default on J-EX4200
switches. You can disable the split and merge feature by using the
virtual-chassis no-split-detection
This topic describes:
What Happens When a Virtual Chassis Configuration Splits on page 712
Merging Virtual Chassis Configurations on page 713
When a Virtual Chassis configuration splits into two separate Virtual Chassis
configurations, the individual member switches detect this topology change and run the
master election algorithm to select a new master for each of the two Virtual Chassis
configurations. The new masters then determine whether their Virtual Chassis
configuration remains active. One of the configurations remains active based on the
following:
It contains both the stable master and the stable backup (that is, the master and
backup from the original Virtual Chassis configuration before the split).
command.
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