cn8237 Mindspeed Technologies, cn8237 Datasheet - Page 127

• 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
5.4.7 Early Packet Discard
Suppression on Multicast
28237-DSH-001-C
Packet Discard—Echo
5.4.7.2 Frame Relay
5.4.7.4 LANE-LECID
5.4.7.3 CLP Packet
5.4.7.1 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.
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 will be set to a logic high. The CNT_ROVR bit in the VCC
table holds this flag information until a status is sent.
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, that is, point-to-multipoint Emulated LAN traffic.
LANE-LECID discard function for that VCC is enabled, and the functions below
are performed.
for up to 32 LECIDs, each a unique identifier for a single LAN Emulation Client.
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.
entry for this channel will be set to a logic high. The CNT_ROVR bit in the VCC
table holds this flag information until a status is sent.
• 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 support
When the RSM coprocessor receives a BOM cell with this function enabled, it
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.
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 will be set to a logic high. The CNT_ROVR bit in the
VCC table holds this flag information until a status is sent.
Mindspeed Technologies
™
5.0 Reassembly Coprocessor
5.4 Buffer Management
5-19