Managing OmniSwitch 6850/6850E Series Stacks
Roles Within the Stack
OmniSwitch 6850/6850E Series Hardware Users Guide
June 2011
page 6-13
Idle Module Role
Switches that are not assigned either the primary or secondary role in a stack are, by default, assigned the
role of
idle
modules. These idle modules operate similarly to Network Interface (NI) modules in a chassis-
based switch.
In the event of a management module failure within the stack, the idle module with the next lowest slot
number in the stack will automatically assume the secondary management role. In other words, if the
primary module in a stack goes down for any reason and the secondary takes over the primary manage-
ment role, the switch must now assign a new secondary module. The idle element with the next lowest slot
number assumes this new responsibility until the situation is corrected and all elements in the stack are
reloaded.
Note.
Primary and secondary management modules also send and receive traffic on their Ethernet ports.
The primary management module is like an NI module with the added task of overall stack management;
the secondary management module is like an NI with the added responsibility of backing up the primary
module in the event of a primary module failure. In other words,
all modules
in the virtual chassis can
send and receive user data, regardless of their roles.
For more information on dynamic assignment of idle modules in a stack, refer to the diagram below:
Secondary Management Module Selection Using Saved Slot Information
Four switches are stacked; all switches are connected via stacking
cables. The stack is booted.
Primary
Secondary
The primary and secondary management modules are dynamically
assigned using any of the methods outlined on pages
6-8
through
6-12
.
2
1
Idle
Idle
Primary
Secondary
The system software automatically assigns the remaining elements
in the stack the idle module role. These modules act as Network
Interface (NI) modules, sending and receiving 10/100/1000
Ethernet traffic on their ports.
In the event of a primary-to-secondary failover, the idle module
with the next-lowest slot number in the stack will assume the
secondary—or backup—management role.
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