RS8234EBGC Mindspeed Technologies, RS8234EBGC Datasheet - Page 47

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

RS8234
ATM ServiceSAR Plus with xBR Traffic Management
28234-DSH-001-B
reassembly process, including the following:
of complete or partial CPCS-PDUs based upon service discard attributes or error
conditions. The early packet discard function halts reassembly of the CPCS-PDU
marked for discard until the next Beginning of Message (BOM) cell and/or the
error condition has cleared. The SAR writes a status queue entry with the
appropriate status flags set, which indicate the reason for the discard. This
function can be enabled for the following conditions:
either Message Mode or Streaming Mode. In Message Mode, a status entry is
written only when the last buffer in a message completes reassembly. In
Streaming Mode, a status entry is written for each buffer as it completes
reassembly.
The RS8234 provides the user with generous per-channel control of the
• Assignment of priorities for reassembly buffer return processing
• Cell filtering on inactive channels
• Mechanisms to establish per-VCC firewalling by allocating buffer credits
• Per-VCC activation and control of a background hardware time-out
• Per-VCC monitoring of the length of the reassembled PDU, with status
The RS8234 implements an early packet discard feature to enable discarding
• Frame Relay discard based on the frame’s DE setting and the channel
• CLP packet discard based on the received cell’s CLP bit setting and
• LANE-LECID packet discard on ELAN channels, which implements echo
• Early packet discard on AAL5 channels when the reassembled PDU length
• Early packet discard on channels encountering a free buffer queue empty
• Early packet discard on PDUs when a DMA Incoming FIFO Full condition
• Early packet discard on channels encountering a reassembly status queue
• Early packet discard on AAL3/4 channels with these MIB errors: ST_ERR
The system designer can set the reassembly status reporting for any channel to
on a per-channel basis. (This limits the possibility of one VCC consuming
all of the memory resources.)
function where the user selects one of eight programmable time-out
periods. (The background function then automatically detects partially
reassembled PDUs and reports this status to the host so that these buffers
can be recovered and re-allocated.)
reporting if the length exceeds a set maximum length for that channel
exceeding a user-defined priority threshold
exceeding channel priority threshold
suppression on multicast data frames
exceeds the user-defined maximum PDU length for that VCC
(underflow) condition (meaning there are no available buffers in the free
buffer queue that channel is assigned to)
occurs
full (overflow) condition
(Segment Type error), SN_ERR (Sequence Number error), and LI_ERR
(SAR-PDU Length error)
Mindspeed Technologies
™
2.4 Automated Reassembly Engine
2.0 Architecture Overview
2-15