Cisco ASR 5000 series Product Overview page 125

Software Architecture
IP forwarding decisions (both unicast and multicast)
Per interface packet filtering, flow insertion, deletion, and modification
Traffic management and traffic engineering
Passing user data frames to/from processing card CPUs
Modifying/adding/stripping datalink/network layer headers
Recalculating checksums
Maintaining statistics
Managing both external line card ports and the internal connections to the data and control fabrics
Card/Slot/Port (CSP) Subsystem: Responsible for coordinating the events that occur when any card is inserted,
locked, unlocked, removed, shut down, or migrated, the CSP subsystem is responsible for all card activity for
each of the 48 slots in the chassis. It is also responsible for performing auto-discovery and configuration of
ports on a newly inserted line card, and determining how line cards map to processing cards (including through
an RCC in failover situations).
The CSP subsystem runs only on the active SMC and synchronizes the information it contains with the
mirrored SCT subsystem on the standby management card. It is started by the SIT subsystem, and monitored
by the HAT subsystem for failures.
Session Subsystem: The Session subsystem is responsible for performing and monitoring the processing of a
mobile subscriber's data flows. Session processing tasks for mobile data calls include: A10/A11 termination for
CDMA2000 networks, GSM Tunneling Protocol (GTP) termination for GPRS and/or UMTS networks,
asynchronous PPP processing, packet filtering, packet scheduling, Diffserv codepoint marking, statistics
gathering, IP forwarding, and AAA services. Responsibility for each of these items is distributed across
subordinate tasks (called Managers) to provide for more efficient processing and greater redundancy. A
separate Session Controller task serves as an integrated control node to regulate and monitor each of the
Managers and to communicate with the other active subsystems.
This subsystem also manages all specialized user data processing, such as for payload transformation, filtering,
statistics collection, policing, and scheduling.
OL-22938-02
Understanding the Distributed Software Architecture ▀
Cisco ASR 5000 Series Product Overview ▄