Redundancy; Redundancy Scenarios - Alcatel-Lucent OmniSwitch AOS Release 6 Manual

CMM Files

Redundancy

CMM software redundancy is one of the switch's most important fail over features. For CMM software
redundancy, at least two fully-operational OmniSwitch Stackable Series switches must be linked together
as a stack or two fully-operational CMM modules must be installed in the chassis at all times. In addition,
the CMM software must be synchronized. (Refer to
on page 5-27 for more information.)
In OmniSwitch Stackable Series switches, one of the switches has the primary role and the another switch
has the secondary role at any given time. (The primary and secondary roles are determined by the switch
number indicated on the LED on the front panel; the lowest number switch becomes the primary switch in
the stack.) The primary switch manages the current switch operations while the secondary switch provides
backup (also referred to as "fail over").
Additional switches in a stack are set to "idle" for the purposes of redundancy. For more information on
managing a stack of switches, see the "Managing Stacks" chapter found in the appropriate Hardware
Users Guide.
When two CMMs are running in an OmniSwitch Chassis-based switch, one CMM has the primary role
and the other has the secondary role at any given time. The primary CMM manages the current switch
operations while the secondary CMM provides backup (also referred to as "fail over").

Redundancy Scenarios

The following scenarios demonstrate how the CMM software is propagated to other switches in a stack for
the purposes of coherent redundancy. In the examples below, W represents the working directory and C
represents the certified directory.
Scenario 1: Booting the Stack
The following diagram illustrates what occurs when a stack powers up. The stack displayed is a three
switch stack.
Switch #1
W
1. Stack is pow-
ered up and boots
from the certified
directory.
page 5-10
Switch #2
C
W
2. The contents of
the certified direc-
tory of the primary
CMM
switch are
copied to the
working directory
of the secondary
CMM
switch.
The working
directory is then
copied to the certi-
fied directory.
Powering Up a Stack
OmniSwitch AOS Release 6 Switch Management Guide
Managing CMM Directory Content
"Synchronizing the Primary and Secondary CMMs"
Switch #3
W
C
3. The contents of
the certified direc-
tory of the pri-
CMM
mary
switch are copied
to the working
directory of addi-
tional switches.
The working direc-
tory is then copied
to the certified
directory.
C
July 2010