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XRT79L71
PRELIMINARY
59
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
1.
Examples of Source and Sink Terminal Equipment would be DS3 ATM UNIs, DS3 POS-PHY Interfaces and M13
Multiplexers/De-Multiplexers.
2.
This transmission path from the Source Terminal Equipment to the Sink Terminal Equipment may involve the
transmission through numerous network elements such as DS3 repeaters and SONET/SDH Mappers, etc.
Figure 16 presents a simple illustration of a DS3 network that consists of these three types of Terminal
Equipment.
Processing at the Source Terminal Equipment
The purpose of the Source Terminal Equipment is to accept some non-DS3 data from some entity (e.g., ATM
cells, PPP packets, DS1 or E1 signals, etc.) and to map this data into payload bits within an outbound DS3
data-stream. As the Source Terminal Equipment constructs each outbound DS3 data-stream, it computes the
EVEN parity value over all of the payload bits, within this outbound DS3 data-stream. This resulting parity
value will be inserted into the two (2) P-bit fields and the three (3) CP-bit-fields within the very next outbound
DS3 frame.
Hence, both the P-bit and CP-bit values within a given DS3 frame will originate from the Source Terminal
Equipment.
Processing at the Mid-Network Terminal Equipment
The Mid-Network Terminal Equipment has the task of doing the following.
Receiving and doing performance monitoring on a given DS3 data-stream from some entity or piece of
equipment (e.g., another remote terminal equipment, SONET/SDH Mapper, a DS3 Source Terminal
Equipment, etc.)
Transmitting this same DS3 data-stream out to some other entity or piece of equipment.
Figure 17 presents a simple illustration of the basic architecture of a Mid-Network Terminal Equipment.
FIGURE 16. A SIMPLE ILLUSTRATION OF THE LOCATIONS OF THE SOURCE, MID-NETWORK AND SINK TERMINAL
EQUIPMENT (FOR CP-BIT PROCESSING)
Source
Terminal
Equipment
Source
Terminal
Equipment
Mid-Network
Terminal
Equipment
Mid-Network
Terminal
Equipment
Sink
Terminal
Equipment
Sink
Terminal
Equipment
DS3 Data-Stream
Non-DS3 Data
(e.g., ATM Cells,
PPP Packets, T1/E1
Data, etc.)
Non-DS3 Data
(e.g., ATM Cells,
PPP Packets, T1/E1
Data, etc.)
DS3 Network