Extreme Networks BlackDiamond 10808 Installation Manual page 79

The BlackDiamond 10K series switch can run with a single MSM installed. When you install an
additional MSM, one of the MSMs operates as the primary, and the other becomes the backup.
The primary MSM is responsible for upper-layer protocol processing and system management
functions. For example, OSPF computation and SNMP functions are performed by the primary MSM.
Packet handling is distributed among the CPUs of all installed MSMs.
When you save the switch configuration, it is saved to all MSMs. If you download a new ExtremeWare
image, the image is downloaded to all MSMs.
Selection of the primary MSM occurs automatically. The following scenarios describe the selection
process:
When the BlackDiamond 10K series switch boots with one or more MSMs already installed and an
MSM is installed in slot A, the MSM in slot A becomes the primary.
When the BlackDiamond 10K series switch boots with a single MSM (regardless of the slot position),
it is selected as the primary.
If additional MSMs are added to the switch after it has been powered on, the added MSM becomes
the backup. MSMs that operate as backups can be inserted and removed without disrupting network
services.
If you remove the primary MSM while the BlackDiamond 10K series switch is operating, the backup
MSM experiences a soft reset and then becomes the primary MSM.
For example, if you have a BlackDiamond 10K series switch with a primary MSM in slot A and a
backup MSM module in slot B, and you remove the primary MSM from slot A, the backup in slot B
becomes the primary.
Table 13 describes the LED activity on the MSM.
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