Agilent Technologies J3972A - Manual (Page 174)

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SAR-PDU
Segmentation and Reassembly Protocol Data Unit
Scrambling
An algorithm applied to a digital signal to eliminate long runs of all zeros or and
ones which would make it difficult to recover the clock. The signal is unscrambled
at the receiver to restore the original. Scrambling also eliminates the possibility of
payload bit patterns accidentally mimicking an alignment or synchronization
pattern at the start of a frame. Scrambling is only applied to the payload of ATM
cells.
SDU
Service Data Unit
Segmentation
The process of partitioning a network message so that it fits within an integral
number of ATM cells consisting of a header and a payload containing a part of the
original network message.
Segmentation and Reassembly (SAR)
Segmentation and Reassembly (SAR) is the process used to map user data to and
from ATM cells. At the transmitting end, information is segmented and sent out in
separate cells (adding padding if necessary). At the receiving end, the AAL takes
the information from the individual cells and reassembles it into its original form.
Sequence number (SN)
A number located in byte 6 of an AAL-1 ATM cell with a value in the range 1
through 7. This sequence number is used to identify the relative position of cells
in a cell stream.
Server
A device on the network that is dedicated to specific functions.
Service
A single call or transmission, such as a telephone conversation, a computer-data
transmission, or a television signal. A multimedia service is a single call carrying
different types of information such as text, graphics, sound and video.