cn8236 Mindspeed Technologies, cn8236 Datasheet - Page 30

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

1.0 CN8236 Product Overview
1.2 Service-Specific Performance Accelerators
1-4
1.2 Service-Specific Performance Accelerators
The CN8236 incorporates several service-specific features, which accelerate
system performance. Some of these service level features provide the possibility
for designers to accelerate specific protocol interworking functions. Other service
level features enable network level functionality. These features are outlined in
Chapter
UNI or NNI Addressing
The CN8236 handles both User-Network Interface (UNI) addresses, which use an
8-bit Virtual Path Identifier (VPI) field, and Network-to-Network Interface (NNI)
addresses, which use a 12-bit VPI field.
Frame Relay Interworking
The VBR traffic category includes rate-shaping via the dual leaky bucket Generic
Cell Rate Algorithm (GCRA) based on the Cell Loss Priority (CLP) bit, for use in
Frame Relay. The CN8236 also implements the Frame Relay discard attribute by
performing early packet discard based on the frame’s DE field and assigned
discard priority.
IP Interworking
The CN8236 facilitates ATM call control signalling procedures as defined in
ATM Forum’s UNI Signalling 4.0 Specification (SIG 4.0), to support IP over
ATM environments. Some of the SIG 4.0 capabilities that are of interest to IP over
ATM and which the CN8236 allows for are as follows:
Guaranteed Frame Rate
The CN8236 can rate-shape ATM Adaptation Layer Type 5 (AAL5) Common
Part Convergence Sublayer Protocol Data Units (CPCS-PDUs, that is, frames) in
the UBR service category, by providing a guaranteed MCR for UBR VCCs.
Early Packet Discard
The EPD feature provides a mechanism to discard complete or partial
CPCS-PDUs based upon service discard attributes or error conditions. The
reassembly coprocessor performs EPD functions under the following conditions:
• ABR signalling for point-to-point calls
• Traffic parameter negotiation
• Frame discard support
• Frame Relay packet discard based on the DE field in the received frame
• Packet discard based on the CLP bit.
• LANE-LECID packet discard to implement echo suppression on multicast
• Packet discard when a firewall condition occurs on a VCC or group.
• Receive FIFO buffer full condition/threshold.
• Various AAL3/4 Management Information Base (MIB) errors.
and the channel exceeding a user-defined priority threshold.
data frames on ELAN channels.
2.0, and are fully described in succeeding chapters.
Mindspeed Technologies
ATM ServiceSAR Plus with xBR Traffic Management
™
28236-DSH-001-B
CN8236