User guide

Configuring Virtual Chassis Virtual Chassis Overview
OmniSwitch AOS Release 7 Switch Management Guide March 2015 page 12-11
License Behavior
The following table describes the behavior of a Slave chassis when attempting to join a VC based on the
installed licenses. A Slave chassis must have the proper license(s) when attempting to join an existing VC.
Based on the type of license installed on the Master, the Slave chassis may fail to join the existing VC or
may inherit the existing licenses.
License Table Matrix
Master/Slave Election
Once all switches complete their initialization their VFLs become operational, they start the virtual chas-
sis protocol. This protocol performs three basic functions including: topology discovery, master election
and keep-alive/hello monitoring. The election of the Master chassis is based on the following criteria,
which are listed from the higher to the lower priority.
1. Current Master Chassis - The current master chassis will remain the master chassis if it is not rebooted.
2. Highest chassis priority value
3. Longest chassis uptime
4. Smallest Chassis ID value
5. Smallest chassis MAC address
Virtual Chassis - Redundancy
• If the Master chassis goes down the Slave chassis will takeover the Master role and all traffic flows
that are based on the multi-homed physical connections will reconverge on the new Master.
• If the Slave chassis goes down the Master chassis will retain its Master role and all traffic flows that
are based on multi-homed physical connections will reconverge on the existing Master.
• If the VFL goes down, the Master chassis will retain its Master role. The Slave chassis will transition
to assume the Master role as well. At this point the virtual chassis topology has been split and there
will be two Masters in the network. If a management EMP network has been configured the Remote
Chassis Detection (RCD) protocol will detect this split topology. In response to this event, the former
Slave chassis will shutdown all its front-panel user ports to prevent duplicate IP and chassis MAC
addresses in the network. The Slave's chassis status will be modified from Running to Split-Topology
to indicate this second pseudo-master chassis is not operational at this point. If the VFL comes back
up, the former Slave chassis will reboot and rejoin the virtual chassis topology assuming its Slave role
again.
Existing Master New Slave Join?
Inherit
License
Note
DEMO Advanced Advanced Yes None
DEMO Advanced Advanced / DC No None License mismatch
Advanced DEMO Advanced Yes None
Advanced / DC DEMO Advanced Yes DC Slave inherits DC
license from Master
Advanced / DC DEMO Advanced / DC Yes None