cn8236 Mindspeed Technologies, cn8236 Datasheet - Page 196

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

6.0 Traffic Management
6.3 ABR Flow Control Manager
6.3.6 Cell Type Decisions
Figure 6-15. Steady State ABR-ER Cell Stream
6-28
6.3.6.1 In-rate Cell
Note: Nominally, Nrm = 32
Streams
FW_RM BW_RM
Since every ABR connection in a network is full duplex, the CN8236 is a Source
and a Destination for each VCC. The CN8236 multiplexes user data cells,
Forward RM cells, and Backward RM cells into the in-rate ABR cell stream.
TM 4.1 Source Behaviors specify rules for the in-rate cell stream.
transmits one Forward RM cell. A Backward RM cell follows. Finally, the Source
sends Nrm user data cells. At steady state, this sequence would be repeated with a
Forward RM cell marking the beginning of each sequence.
characteristics of ABR connections, all connections do not maintain a steady state
sequence. Furthermore, since it is an immature specification, the rules for cell
interleaving of in-rate cell streams may be modified slightly.
specification on cell stream interleaving. This Cell Type Decision algorithm
makes on-the-fly decisions concerning which type of cell to send, based on the
current state of the connection.
algorithm. The ABR Flow Control Manager chooses a cell type based on a Cell
Decision table and the VCC state. The segmentation coprocessor then formats the
appropriate cell type and sends it on the ABR in-rate cell stream.
NOTE:
One FORWARD_RM Cell Period
Figure 6-15
Unfortunately, due to the asynchronous, asymmetrical, and fluctuating
The CN8236 provides a programmable mechanism to comply with TM 4.1’s
The ABR Flow Control Manager may choose to send no cell. This occurs
when the VCC has no user data to segment.
Mindspeed Technologies
Nrm Data Cells
shows the desired result of the specification. First, the Source
ATM ServiceSAR Plus with xBR Traffic Management
Figure 6-16
™
FW_RM
shows a block diagram of the
BW_RM
28236-DSH-001-B
CN8236
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