Managing OmniSwitch 6450 Stacks Roles Within the Stack
Roles Within the Stack Managing OmniSwitch 6450 Stacks
Using Saved Slot Information
The saved slot number is the slot number the switch will assume following a reboot. This information is stored in a switch’s boot.slot.cfg file; the switch reads its slot number assignment from this file at bootup and assumes the specified slot number within the stack.
If switches in a stacked configuration have no preconfigured slot assignments, the slot number for each switch is dynamically assigned by the system software. Slot numbers can also be manually assigned by the user. For more information on manually assigning slot numbers, refer to “Manual Slot Number Assign-ment” on page 7-23.
When a stack with preconfigured slot information is booted, it is not the lowest MAC address that deter-mines the primary management module. Instead, the slot information stored in each switch’s boot.slot.cfg is read by the system software and used in determining the primary. The switch with the lowest saved slot number becomes the primary management module.
Note. Although, for ease-of-management purposes, it is recommended that slot numbers are assigned beginning with slot number 1, it is not a requirement. In other words, a stack of four switches can have slot assignments 3, 4, 5, and 6. However, it is important that each element in a stack is assigned a unique slot number. Do not assign duplicate slot numbers to elements in a stack. Otherwise, one or more switches will be forced into pass-through mode. For more information on pass-through mode, refer to page 7-13.
For more information on using saved slot information to determine the primary switch in a stack, refer to the diagram below:
Primary Management Module Selection Using Saved Slot Information
Slot 6 Slot 5
Slot 4
Primary: Slot 3 Assumes Slot 6 Assumes Slot 5 Assumes Slot 4 Assumes Slot 3 Saved Slot 6
Four OmniSwitch 6450 switches are stacked; all switches are connected via stacking cables. The user configures each switch to have a unique saved slot number. When each saved slot number is configured, the information is automatically
written to the boot.slot.cfg file located in the /flash directory of each switch.
The user reloads all the elements in the stack either by issuing the reload all command or by physically powering off and then powering on all switches.
Instead of assigning the primary management module based on the lowest MAC address, the system software reads the slot information from each switch’s boot.slot.cfg file during the boot process. The switches in the stack come up using their assigned slot numbers.
The switch with the lowest assigned slot number automatically assumes the primary management role.
In this case, the switch assigned slot 3 has the lowest slot number in the stack and becomes the primary management module.
1
2
3
4
Saved Slot 5 Saved Slot 4 Saved Slot 3
Reload
Managing OmniSwitch 6450 Stacks Roles Within the Stack
Using Switch Uptime
A user can override both the MAC address and saved slot methods for determining a stack’s primary management module. This is done by controlling the uptime of switches in the stack. If all elements of a stack are powered off, the user can force a particular switch to become primary by powering on that switch and waiting a minimum of 15 seconds before powering on any other switches. This can be useful if the user wants a switch placed in a specific location, e.g., the top-most switch in a stack, to become the primary.
As with the lowest MAC address method, the primary management module is dynamically assigned slot number 1 when the stack is booted.
For more information on using saved slot information to determine the primary switch in a stack, refer to the diagram below:
Primary Management Module Selection Using Switch Uptime
Powered On
Powered On Powered On
Off Four OmniSwitch 6450 switches are stacked and connected
via stacking cables. All switches are currently powered off.
The user powers on a single switch in the stack. In this case, the bottom-most switch is powered on.
The user now powers on the remaining switches in the stack in short succession.
In this example, when the remaining switches come online, each has a lower saved slot value than the switch powered on at step 1. However, the switch powered on at step 1—with its slot value of 8—retains its primary management role. The joining switches are essentially ineligible for primary status because they are considered “late arrivals.”For the primary switch to forfeit its role to the switch with the lowest assigned slot number (in this case, slot number 1), the stack must be rebooted by the user either by issuing the reload all command or by pow-ering off and powpow-ering on all switches in close succession.
1
2
3
Off Off Powered On
Off Off Off Primary (Saved Slot 8)
Primary
(Saved Slot 8)
Saved Slot 3 Saved Slot 1
Saved Slot 2 Primary (Saved Slot 8)
The user allows a minimum of 15 seconds to pass.
Because no other switches have joined the stack, the switch that was powered on considers itself a stand-alone. The switch assumes a primary role by default—
even if there is a high saved slot number in its boot.slot.cfg file (e.g., 8).
4
Roles Within the Stack Managing OmniSwitch 6450 Stacks