RS8234EBGC Mindspeed Technologies, RS8234EBGC Datasheet - Page 129

• Manufacturer Part Number: RS8234EBGC
• Description: RS8234EBGC ATM XBR SAR
• Manufacturer: Mindspeed Technologies

RS8234
ATM ServiceSAR Plus with xBR Traffic Management
5.4.8 Early Packet Discard
Suppression on Multicast
28234-DSH-001-B
Packet Discard—Echo
5.4.8.2 Frame Relay
5.4.8.4 LANE-LECID
5.4.8.3 CLP Packet
5.4.8.1 General
Packet Discard
Data Frames
Description
Discard
The packet discard feature provides a mechanism to discard complete or partial
CPCS-PDUs, based upon service discard attributes or error conditions.
The EPD feature performs these basic functions:
The frame relay discard attribute is contained in the BOM cell of a CPCS-PDU. If
the FRD_EN bit in the RSM VCC table is a logic high, the frame relay packet
discard function for that VCC is enabled, and the functions below are performed:
If the CLPD_EN bit in the RSM VCC table is a logic high, the Cell Loss Priority
packet discard function for that VCC is enabled, and the following functions
below are performed:
The system designer can use this feature to discard superfluous traffic on the
ATM network caused by LAN Emulation Clients (LECs) transmitting multicast
frames, i.e., point-to-multipoint Emulated LAN traffic.
LANE-LECID discard function for that VCC is enabled, and the functions below
are performed:
• Halts reassembly of the CPCS-PDU marked for discard until the next
• Writes a status queue entry with the EPD bit set and other appropriate
• When the reassembly coprocessor receives a BOM cell on a VCC with this
• If the SERV_DIS counter rolls over, the CNT_ROVR bit in the next status
• When the RSM coprocessor receives a cell and this function is enabled, it
• If the SERV_DIS counter rolls over, the CNT_ROVR bit in the next status
If the LECID_EN bit in the RSM VCC Table is a logic high, the
• The DPRI field is used as an index into the LECID table. This allows
• When the RSM coprocessor receives a BOM cell with this function
• If the SERV_DIS counter rolls over, the CNT_ROVR bit in the next status
BOM cell and the error condition has cleared.
STATUS and PDU_CHECKS bits set, based on the reason for the discard.
feature enabled, it checks the 1-bit DE field in the frame relay header. If
this bit is a logic high, and the channel priority (the DPRI in the RSM VCC
table) is less than or equal to the global priority, RSM_CTRL (GDIS_PRI),
the RSM coprocessor discards the cell, marks the rest of the packet for
discard, and increments the SERV_DIS counter in the VCC table. All cells
on that channel up to the next BOM are discarded.
entry for this channel is set to a logic high. The CNT_ROVR bit in the
VCC table holds this flag information until a status is sent.
checks the 1-bit CLP field in the ATM header. If this bit is a logic high,
and the channel priority is less than or equal to the global priority,
RSM_CTRL (GDIS_PRI), the RSM coprocessor discards the cell, marks
the rest of the packet for discard, and increments the SERV_DIS counter in
the VCC table. All cells on that channel up to the next BOM are discarded.
entry for this channel is set to a logic high. The CNT_ROVR bit in the
VCC table holds this flag information until a status is sent.
support for up to 32 LECIDs, each a unique identifier for a single LAN
Emulation Client.
enabled, it checks the 16-bit LECID field in the LANE header against the
value in the LECID table. If a match occurs, the RSM coprocessor discards
the cell, marks the rest of the packet for discard and increments the
SERV_DIS counter in the VCC Table.
Mindspeed Technologies
™
5.0 Reassembly Coprocessor
5.4 Buffer Management
5-25