28236-DSH-001-B_15 Datasheet, PDF (111/443 Pages) M/A-COM Technology Solutions, Inc. – ATM ServiceSAR Plus with xBR Traffic Management

5
5.0 Reassembly Coprocessor
5.1 Overview
The reassembly (RSM) coprocessor processes cells received from the ATM PHY
Interface block. The coprocessor extracts the AAL SDU payload from the
received cell stream and reassembles this information into buffers supplied by the
host system. The CN8236 supports AAL5, AAL3/4, and AAL0 reassembly, and
cell mode (1-cell PDUs through a Virtual FIFO buffer, for CBR voice traffic).
The CN8236 reassembles up to 64 K VCCs simultaneously. Individual
connections are identified through separate VPI and VCI Index table structures.
The VPI/VCI Index table mechanism provides very fast, consistent channel
identification over the full range of VPI/VCI addresses.
CPCS-PDU payload data, the CPCS-SDU, fills the host-supplied data buffers
assigned to each VCC. The host assigns each VCC to one or two of 32
independent buffer pools, from which the RSM coprocessor draws buffers as
needed.
The CN8236 extracts the CPCS-SDU from the CPCS-PDU, writes the SDU to
host-supplied buffers, and performs all CPCS-PDU checks. The results of these
checks and AAL information are passed to the host on one of 32 independent
status queues.
This chapter provides information on the functions and data structures of the
reassembly coprocessor. For detailed information on how the CN8236 handles
PM cells, deals with OAM functions, and interacts with the segmentation
coprocessor in handling traffic management and scheduling, refer to Chapter 6.0,
and Chapter 7.0.
28236-DSH-001-B
Mindspeed Technologies™
5-1