cn8237 Mindspeed Technologies, cn8237 Datasheet - Page 47

• Manufacturer Part Number: cn8237
• Description: Atm Oc-12 Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

CN8237
ATM OC-12 ServiceSAR Plus with xBR Traffic Management
28237-DSH-001-C
2.4 Automated Reassembly Engine
The reassembly 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.
reassembly VCC table located in RSM memory. One RSM VCC table entry
defines the negotiated or contracted characteristics of the reassembly traffic for a
particular channel. Each table entry is initialized by the host during system
initialization, or on-the-fly. The SAR uses the RSM VCC table to store temporary
information to assist the reassembly process. An initialized Reassembly VCC
table entry effectively establishes a connection on which the CN8237 can
reassemble data.
up to 64 K VCCs simultaneously at a maximum rate of 600 Mbps on simplex and
full-duplex connections. The Channel Directory mechanism allows flexible
preallocation of resources and provides deterministic channel identification over
the full UNI or NNI Virtual Path Identifier/Virtual Channel Identifier (VPI/VCI)
address space. The total number of VCCs supported is limited by the memory
allocated to the RSM VCC table and the Channel Directory.
cell stream and reassembles this information into system buffers allocated
per-VCC. The CN8237 supports AAL5 and AAL0 reassembly, as well as 52-octet
Raw Cell mode.
overhead.
this mode the Header Error Check (HEC) octet is deleted to align the 53-octet cell
to 32-bit boundaries, and the RSM coprocessor reassembles the entire 52-octet
ATM cell into the reassembly buffer.
Each active reassembly Channel is specified as a single entry in the
Using a dynamic Channel Directory lookup method, the CN8237 reassembles
The reassembly coprocessor extracts the AAL SDU payload from the received
For AAL5, the reassembly coprocessor extracts and checks all PDU protocol
The CN8237 provides two methods of terminating an AAL0 PDU:
1.
2.
The AAL0 PDU termination method is selectable on a per-VCC basis.
The user can, on a per-channel basis, establish Raw Cell mode reassembly. In
Payload Type Identifier (PTI) termination, wherein the PTI bit in the cell
header is monitored for the End of Message (EOM) cell indication.
Cell Count termination, wherein the CN8237 terminates the PDU when a
user-defined number of cells have been received on that channel.
Mindspeed Technologies
™
2.4 Automated Reassembly Engine
2.0 Architecture Overview
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