cn8236 Mindspeed Technologies, cn8236 Datasheet - Page 48

• Manufacturer Part Number: cn8236
• Description: Atm Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

2.0 Architecture Overview
2.4 Automated Reassembly Engine
2-14
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.
VCC table located in SAR-shared 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 CN8236 can
reassemble data.
up to 64 K VCCs simultaneously at a maximum rate of 200 Mbps on simplex
connections and 155 Mbps on 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 CN8236 supports AAL5, AAL3/4, and AAL0 reassembly and
52-octet Raw Cell mode.
overhead.
checking procedures incorporated in AAL3/4, and reassembles SDUs based on
Message ID (MID).
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 reassembly
Using a dynamic Channel Directory lookup method, the CN8236 reassembles
The reassembly coprocessor extracts the AAL SDU payload from the received
For AAL5, the reassembly coprocessor extracts and checks all PDU protocol
For AAL3/4, the reassembly coprocessor performs all error detection and
The CN8236 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, where the PTI bit in the cell
header is monitored for the End of Message (EOM) cell indication.
Cell Count termination, where the CN8236 terminates the PDU when a
user-defined number of cells have been received on that channel.
Mindspeed Technologies
ATM ServiceSAR Plus with xBR Traffic Management
™
28236-DSH-001-B
CN8236