Chassis Management Module (CMM)
CMM Redundancy
OmniSwitch 7700/7800 Hardware Users Guide
April 2005
page 4-9
CMM Redundancy
CMM redundancy is one of the switch’s most important failover features. For CMM redundancy, two
fully-operational CMM modules must be installed in the chassis at all times. In addition, the software on
the two CMM modules must be synchronized. (Refer to
“Synchronizing the Primary and Secondary
for more information.)
When two CMMs are running in the switch, one CMM has the primary role and one CMM 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 “failover”).
In a redundant configuration, if the primary CMM fails or goes offline for any reason, the secondary
CMM is instantly notified. The secondary CMM automatically assumes the primary role.
CMM Failover Sequence
The figure below illustrates the CMM failover sequence:
1
CMM A (installed in the left-hand Slot A position) is operating in the primary mode. CMM B
(installed in the right-hand Slot B position) is operating in the secondary mode—i.e., it is functioning as
the standby CMM and is ready to take over chassis management functions in the event of a primary CMM
failure.
2
CMM A fails or is taken offline (e.g., the module is physically removed from the chassis).
3
CMM B automatically assumes the primary role.
Redundant CMM Failover
Ethernet Management Ports (EMPs) and Redundancy
.
In redundant CMM configurations, the
Ethernet Management Port (EMP) is only operational on the
primary
CMM. For additional information
on the EMP, refer to
OS7-ENI-C24
1x
3x
5x
7x
OS7-ENI-C24
1x
3x
5x
OK1
OK2
8x
6x
4x
4
5
CMM
A
B
OS7700-CMM
OK1
OK2
PRI
SEC
TEM
P
FA
N
OS7700-CMM
OK1
OK2
PRI
SEC
TEMP
FA
N
OS7-GNI-U2
OK1
OS7-ENI-C24
1x
3x
5x
7x
OS7-ENI-C24
1x
3x
5x
OK1
OK2
8x
6x
4x
4
5
CMM
A
B
OS7700-CMM
OK1
OK2
PRI
SEC
TEM
P
FA
N
OS7700-CMM
OK1
OK2
PRI
SEC
TEMP
FA
N
OS7-GNI-U2
OK1
!
CMM B
(Primary)
CMM A
(Primary)
CMM B
(Secondary)
CMM A fails or
is taken offline
