ibm3206k0424 ETC-unknow, ibm3206k0424 Datasheet - Page 362

• Manufacturer Part Number: ibm3206k0424
• Description: Ibm Processor For Network Resources
• Manufacturer: ETC-unknow

IBM3206K0424
IBM Processor for Network Resources
RXRTO Block Diagram
RXRTO Functional Description
RXRTO performs periodic reassembly timeout processing and LCD update operations.
Reassembly Timeout (RTO) Processing
Reassembly timeout processing is generally an AAL5 operation. It is supported for other LCD types as well. It
can be enabled on an LCD basis by turning on the RTO enable bit in the LCD. The following registers also
need to be properly set up to run RTO processing:
See the register descriptions for more register details.
The LCD table registers define the LCD table that the RTO process examines. The value register is used as
a compare value against a counter that counts based on a pre-scaler. Each time the registers compare, RTO
processing is started for a single LCD and the time base is reset. RTO processing checks the RTO test and
set bit. If it is reset, it sets it and continues. If it is set, then a timeout occurs and the LC is placed in error state
and the current packet is surfaced to the user via an event. Any resource associated with the packet must be
recovered by software. For example, if the LCD is setup to use scatter mode, then there may be scatter DMA
pages in the DMA list that need to be returned to the proper receive queue. The RTO bit is reset with each
inbound cell received. An LCD needs to be touched twice to cause a timeout (once to set it and once to detect
that it is already set).
The time base starts running as soon as the RTO processing is complete. Thus, RTO processing is a low
priority task.
Shutting Down an LCD
To shut down a receive LCD, the following steps should be followed:
Cell/Packet Re-assembly (REASM)
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• RXRTO RTO LCD Table Bound Registers
• RXRTO Reassembly Timeout Value Register
• RXRTO Reassembly Timeout Pre-Scaler Register
• Clear the entry for this LCD in the LCD table (to stop receiving cells for this LCD)
• Do an LCD update operation that sets LCD state to down
• Read the LCD REASM ptr
• If REASM ptr is non-zero and LCD is set up to do cut through, be sure to free any DMA descriptor that
• If REASM ptr is non-zero and LCD is set up to do scatter, be sure to free any pages in the DMA list
• If REASM ptr is non-zero, free it to POOLS
was added with cut through operation
RXRTO
PM Read/Write Interface
RTO Nano Processor
RXLCD Interface
RXQUE
Interface
POOLS
Interface
pnr25.chapt05.01
August 14, 2000
Preliminary