tdat04622 ETC-unknow, tdat04622 Datasheet - Page 100

• Manufacturer Part Number: tdat04622
• Description: Tdat Sonet/sdh 155/622/2488 Mbits/s Data Interfaces
• Manufacturer: ETC-unknow

TDAT042G5 SONET/SDH
Data Sheet
155/622/2488 Mbits/s Data Interface
May 2001
Functional Description
(continued)
Data Engine (DE) Block
(continued)
Receive Data Engine (continued)
COUNTER EQUALS Y
VERIFICATION
SYNCHRONIZED
COUNTER LESS
COUNTER DROPS
THAN Y
BELOW V
COUNTER DROPS
BELOW W
COUNTER EQUALS X
ACQUISITION
COUNTER LESS
THAN X
5-8388(F)
Note: Even in synchronized mode, the confidence counter can continue to increase up to the Z value.
31
Figure 14. State Diagram for the X
Scrambler Synchronization Process
SDL Frame Processor. The SDL frame processor consists of an SDL framer, which detects the start of SDL pack-
48
ets, and an (optional) X
unscrambler, which is used to unscramble payload data. SDL packets can also arrive
unscrambled, in which case the unscrambler is disabled. The SDL frame processor can frame packets in SDL form
which contain a data length between 4 and 65,535 bytes.
The SDL framer uses a CRC-16 check upon 2 bytes sequences used to determine packet length in order to frame
SDL packets. Since the framer is designed to support data that is not byte-aligned, 32 separate framers may be
used to search for the CRC-16 pattern. If the data is byte-synchronized, only four framers are needed. A confi-
dence counter is used to gauge the framer’s ability to frame SDL packets consistently. When the confidence
counters reaches a certain level (defined by the programmable SDL delta counter register), the framer is in sync
state. Single-bit error correction for the SDL headers is also supported. Shown below in Figure 15 is the general
structure of the SDL packets. In this figure, there is no interpacket fill.
PACKET
PACKET
PACKET PAYLOAD
CRC-16
PACKET PAYLOAD
CRC-16
PACKET PAYLOAD
LENGTH
LENGTH
5-8386(F)r.2
Figure 15. General Structure of SDL Packets
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Agere Systems Inc.