User's Manual

40 Installing and Setting Up the CMC
The CMC is connected to the management network. All external access to
the CMC and iDRACs is accomplished through the CMC. Access to the
managed servers, conversely, is accomplished through network connections
to I/O modules (IOMs). This allows the application network to be isolated
from the management network.
NOTE: It is recommended to isolate chassis management from the data network.
Dell cannot support or guarantee uptime of a chassis that is improperly integrated
into your environment. Due to the potential of traffic on the data network, the
management interfaces on the internal management network can be saturated by
traffic intended for servers.This results in CMC and iDRAC communication delays.
These delays may cause unpredictable chassis behavior, such as CMC displaying
iDRAC as offline even when it is up and running, which in turn causes other unwanted
behavior. If physically isolating the management network is impractical, the other
option is to separate CMC and iDRAC traffic to a separate VLAN. The CMC and
individual iDRAC network interfaces can be configured to use a VLAN with the
racadm setniccfg command. For more information, see the
Dell Chassis
Management Controller Administrator Reference Guide
.
If you have one chassis, connect the CMC and the standby CMC to the
management network. If you have a redundant CMC, use another network
cable and connect the GB CMC port to a second port of the management
network.
If you have more than one chassis you can choose between the basic
connection, where each CMC is connected to the management network, or a
daisy-chained chassis connection, where the chassis are connected in series
and only one CMC is connected to the management network. The basic
connection type uses more ports on the management network and provides
greater redundancy. The daisy-chain connection type uses fewer ports on the
management network but introduces dependencies between CMCs, reducing
the redundancy of the system.
For more information on daisy-chained connection, see "Daisy-chain CMC
Network Connection" on page 31."
NOTE: Failure to cable the CMC properly in a redundant configuration can cause
loss of management and create broadcast storms.
Configuring the CMC Network
NOTE: Changing your CMC Network settings may disconnect your current
network connection.