Managing OmniSwitch 6855 Series Stacks
Roles Within the Stack
OmniSwitch 6855 Series Hardware Users Guide
September 2011
page 7-7
Primary Management Module Selection
For a stack of OmniSwitches to operate as a virtual chassis, there must be a mechanism for dynamically
selecting the switch within the stack that will assume the primary management role. OmniSwitches use
three different methods for selecting the primary switch. These methods are:
•
Chassis MAC address
•
Saved slot number
•
Chassis uptime
Note.
Information on
secondary management module
selection is provided on
page 7-10
. Information on
dynamic assignment of
idle module
roles is provided on
page 7-12
.
Using the Chassis MAC Address
By default, the primary management role will be given to the switch with the lowest chassis MAC
address. However, for this to occur, all switches in the stack
must be booted within 15 seconds of each
other
. In addition, switches in the stack
must have no preconfigured slot information
. Because of these
two conditions, the MAC address method for selecting the primary module usually occurs with new “out
of the box” switches, or switches from which any preconfigured slot information has been cleared.
For more information on using the lowest MAC address to determine the primary switch in a stack, refer
to the diagram below:
Primary Management Module Selection Using the Lowest Chassis MAC Address
Note.
During the boot process, all other switches in the stack are also dynamically assigned unique slot
numbers. As with the primary switch, these slot numbers are saved to the
boot.slot.cfg
file, located in the
/flash file directory of each switch. For more information on dynamic slot number assignment, refer to
“Slot Numbering” on page 7-20
.
A stack of four OmniSwitches s booted. All switches are
powered on within 15 seconds of each other. In addition,
there is no preconfigured slot information on any of the
switches.
00:d0:95:b2:3c:8e
00:d0:95:b2:2a:ab
00:d0:95:b2:1c:ff
00:d0:95:b2:5b:8d
When the stack is booted, system software detects the lowest
MAC address. In this stacked configuration, the lowest
MAC address is 00:d0:95:b2:1c:ff.
2
1
00:d0:95:b2:3c:8e
00:d0:95:b2:2a:ab
Primary Module
00:d0:95:b2:5b:8d
The system software immediately assigns the correspond-
ing switch the primary management role. When the switch
is assigned as primary, it is also dynamically assigned the
lowest slot number in the stack—i.e., slot 1. This slot
number information is saved to the
boot.slot.cfg
file,
located in the switch’s /flash file directory.
3
