Virtual Chassis Overview Configuring Virtual Chassis
page 9-10 OmniSwitch AOS Release 7 Network Configuration Guide June 2013
Virtual Chassis - Boot-Up
The Master chassis contains the vcboot.cfg file that contains the configuration for the entire virtual chas-
sis. All the switches (i.e. the one that will eventually become the Master and the ones that will become
Slaves) contain a vcsetup.cfg file that allows them to establish an initial connection over a VFL to all the
other neighboring switches.
1 Upon boot-up, a switch will read its local vcsetup.cfg file and attempt to connect to the other neighbor
switches.
2 Upon connection, the switches will exchange the parameters configured in their local vcsetup.cfg files.
3 As a result of this exchange, they will discover the topology, elect a Master based on criteria described
in the next section, start periodic health checks over the VFL and synchronize their configuration as
defined within the vcboot.cfg configuration file.
4 All Slaves, if they do not have a local copy of vcboot.cfg, or their local copy does not match the copy
found on the Master, will download their complete vcboot.cfg from the Master chassis and reboot using
this copy of vcboot.cfg as its configuration file.
Startup Error Mode
If a switch is unable to successfully come up in virtual chassis mode, it enters a special fallback mode
called start up error mode. A switch moves to start up error mode if either one of the following conditions
occur:
• The vcsetup.cfg and vcboot.cfg configuration files are present in the running directory, but no valid
advanced license is installed on the switch.
• The vcsetup.cfg file is corrupted or edited in such a way that it is unable to read a valid chassis identi-
fier in the appropriate range.
A switch start up error mode will keep all of its front-panel user ports, including the virtual-fabric links
member ports disabled. This mode can be identified on the switch by using the show virtual-chassis
topology command. The chassis role will display Inconsistent, whereas the chassis status will show either
one of the following values:
• Invalid-Chassis-Id: The chassis is not operational in virtual chassis mode because no valid chassis
identifier has been found in the configuration. Typically this means that the vcsetup.cfg file is
corrupted, empty or contains an invalid (e.g. out of range) chassis identifier.
• Invalid-License: The chassis is not operational in virtual chassis mode because no valid advanced
license has been found.
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. Highest chassis priority value
2. Longest chassis uptime
3. Smallest Chassis ID value
4. Smallest chassis MAC address
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