Freescale Semiconductor MPC8260 PowerQUICC II Family Reference Manual page 1104

Inverse Multiplexing for ATM (IMA)
I
Layer Sublayer
ATM —
IMA Specific
Transmission
Convergence
Physical
Interface
Specific
Transmission
Convergence
Physical
Medium
Dependent
The PowerQUICC II's IMA microcode alone does not implement all of these functions. Software running
on the PowerQUICC II is responsible for managing the start-up procedure, handling changes in group
control, status, and maintaining the Link State Machine and Group State Machine. In general, the
PowerQUICC II IMA microcode implements most of the IMA sublayer user plane functions and provides
interrupts/statistics for the layer and plane management functions.
The key features of the IMA microcode are:
• Supports any FCC with multi-PHY UTOPIA capability
• Supports both IMA links and non-IMA links on the same FCC (on a per-PHY basis)
• Supports up to 8 IMA groups with one FCC
• Supports up to 8 links per IMA group using an internal TC layer hardware
• Supports up to 31 links per IMA group using an external TC layer device. Note that a maximum
of 31 total links can be supported either on FCC1 or FCC2 but not concurrently on both FCCs)
• Performs the following IMA User Plane functions
— ATM cell stream splitting and reconstruction
— ICP cell insertion/removal--communication of control and framing information
— Cell rate decoupling--insertion of 'filler' cells when ATM layer cells are unavailable
— IMA frame synchronization--finding IMA frame boundaries within links
— Stuffing--insertion of 'stuff' cells into fast links, in order to maintain an average data rate
between links of a group
33-2
Table 33-1. IMA Sublayer in Layer Reference Model
User Plane
Functions
—
• ATM cell stream splitting
and reconstruction
• ICP Cell Insertion &
Removal
• Cell Rate decoupling
• IMA frame synch
• Stuffing
• Discarding bad-HEC cells
• No cell discarding
• No cell rate decoupling
• Cell delineation
• Cell scrambling &
descrambling
• Header error correction
• HEC generation &
verification
• Bit timing
• Line coding
• Physical Medium
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Layer Management
Functions
—
• IMA connectivity
• ICP cell errors (OIF)
• LIF/LODS/RDI-IMA defect
processing
• RDI-IMA alarm generation
• Tx/Rx IMA link state report
—
• HEC error indication
• LCD-RDI alarm
Generation
• Local alarm processing
• RDI alarm generation
Plane Management
Functions
—
• IMA group configuration
• Link addition/removal
• ATM cell rate change
• IMA group failure
notification
• IMA statistics
—
• LCD failure notification
• TC statistics
• Link failure notification
• PMD state
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