7750 SR-a4 and 7750 SR-a8 Overview
7750 SR-a4 and SR-a8 Installation Guide 31
7750 SR-a Modules
The 7750 SR-a modules are designed for use in the 7750 SR-a4 and 7750 SR-a8 chassis. This
section describes the following modules:
• CPM-a on page 31
• IOM-a on page 35
• MDA-a Cards on page 36
CPM-a
The CPM-a, which is used in the 7750 SR-a4 and 7750 SR-a8, provides:
• control plane functions and determines the route tables
• management and console interfaces for system management
• system synchronization interfaces for external synchronization input and output
signals
• alarm interface and notifications
The CPM-a does not provide a switch fabric. The IOM-a forwards traffic from the ingress to
the egress ports.
At least one CPM-a must be installed in the 7750 SR-a chassis. The system cannot boot
without a CPM-a installed in the chassis. Two CPM-a cards are required for system
redundancy. The redundant standby (secondary) CPM-a operates in standby mode and takes
over system operation if the active (primary) CPM-a fails. The 7750 SR-a CPM-a is intended
only for the 7750 SR-a chassis and is not interchangeable with other 7750 SR products.
The CPM-a is field-replaceable and hot-swappable. Refer to the 7750 SR OS Basic System
Configuration Guide for information about CPM-a redundancy.
Each CPM-a supports two, Type-II capable compact flash (CF) memory devices:
• external CF slot—CF slot accessible from the front of the CPM-a card. The slot can
support CF cards up to 32 Gbytes, and can be used to store accounting records, logs,
and TiMOS images.
• internal CF slot—CF slot accessible on the circuit board when the CPM-a is removed
from the chassis. This slot is used for the CF card that contains the system OS. See
CPM-a Internal CF Drive on page 34 for more information.
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