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IBM Packet Routing Switch Serial Interface Converter
12. Glossary
12.1 Definitions
Small portion of fixed length data transported as an entity and not partitioned further. IBM Packet Routing Switch Serial
Interface Converter Cell is 64 - 80 bytes long in steps of four bytes
Cell
Packet
Used interchangeably with cell
Stream of packaged data which is multiple of packet length divided by four (so equal to LU length) for instance in the
back pressure link if there are only two priorities in use then the frame length of the framing signal will be two equivalent
to two logical Unit of the IBM 28.4G Packet Routing Switch or two packet of data where the length of data packet is
expressed in words (4 bytes/32 bits)
Frame
Ingress
Egress
Towards the switch core, corresponds to the data RECEIVED by the switch.
Away from the switch core, corresponds to the data TRANSMITTED by the switch.
12.2 Terms, Abbreviations, and Acronyms
Bit Map addressing: if there is a ‘1’ in this field, the data which is within the same packet is for the corresponding output
port of the IBM 28.4G Packet Routing Switch
BM
Control packet communicates with the switch control. The bit map of such a packet is set to all zero. Upon detecting such
Control
CRC
value the switch automatically route the packet to the switch control. In response the switch control can also insert control
packet in the output queues of the switch.
Cyclic Redundancy Check. A code used to validate a block of data. A CRC8 is used in the IBM Packet Routing Switch
Serial Interface Converter
In Band Flow Control corresponds to the case where the switch flow control information (output queue grant and memory
grant in the egress direction and send grant in the ingress direction) are carried within any contiguous packets (idle or
data) flowing between the protocol engine and the converter.
IBFC
Idle
LU
Idle packets are used as time fill packet to maintain the integrity of the bus when there is no data
Logical Unit. Defines the length of an 8-bits row of data processed by a single shared memory within the switch. The IBM
Packet Routing Switch Serial Interface Converter handles LUs of 16 to 20 bytes corresponding to packet sizes of 64 to 80
bytes.
Out of Band Flow Control corresponds to the case where the switch flow control information (output queue grant and
memory grant in the egress direction and send grant in the ingress direction) is carried through RXENB or TXFULL.
OBFC
PE
Protocol Engine (protocol processor, ATM layer...) is the device that attaches on the line side to the IBM Packet Routing
Switch Serial Interface Converter which runs the higher layer protocols.
PQ
Packet Qualifier is a byte of information used by the switch to interpret packet priority, packet idle or data, or packet color.
Reserved for future use
Res
Shared DASL Controller (also called M3 picoprocessor)controls the DASL transceiver for the delay line management for
temperature tracking, clock drift....
SDC/M3
Service
Synch
Service packet is any fill up packet (idle resulting from a flow control situation or an empty link) or any physical layer inter-
face packet to check the continuity of a link packet (yellow packet)
Synchronization packets are service packets used to train the receiver of the DASL in order to acquire bit/Byte/Packet
synchronization.
IBM Packet
Routing
Switch Serial Chip performing UTOPIA-3 like parallel interface to switch DASL interface conversion
Interface
Converter
Service packet used to check the continuity of the physical link between the IBM 28.4G Packet Routing Switch and the
IBM Packet Routing Switch Serial Interface Converter
Yellow
prssi.02.fm
Glossary
Page 153 of 154
March 1, 2001
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