Inverse Multiplexing for ATM (IMA)
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
33-2 Freescale Semiconductor
I
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
Table33-1. IMA Sublayer in Layer Reference Model
Layer Sublayer User Plane
Functions
Layer Manageme nt
Functions
Plane Management
Functions
ATM — ———
Physical
IMA Specific
Transmission
Convergence
ATM cell stream splitting
and reconstruction
ICP Cell Insertion &
Removal
Cell Rate decoupling
IMA frame synch
Stuffing
Discarding bad-HEC cells
IMA connectivity
ICP cell errors (OIF)
LIF/LODS/RDI-IMA defect
processing
RDI-IMA alarm generation
Tx/Rx IMA link state report
IMA group configuration
Link addition/removal
ATM cell rate change
IMA group failure
notification
IMA statistics
Interface
Specific
Transmission
Convergence
No cell discarding
No cell rate decoupling
——
Cell delineation
• C ell scrambling &
descrambling
Header error correction
HEC generation &
verification
HEC error indicati on
LCD-RDI alarm
Generation
LCD failure notification
TC statistics
Physical
Medium
Dependent
Bit timing
Line coding
Physical Medium
Local alarm processing
RDI alarm generation
• Li nk failure notification
•PMD state