tdat04622 ETC-unknow, tdat04622 Datasheet - Page 90

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

TDAT042G5 SONET/SDH
155/622/2488 Mbits/s Data Interface
Functional Description
Path Terminator (PT) Block
The path terminator performs path overhead (POH) termination and extracts the payload for further processing by
the downstream circuitry. The path terminator block interprets the incoming H1/H2 pointer of each incoming STS
channel. The pointer interpreter supports up to four channels and performs path overhead termination on each
channel. Each channel may be either an STS-1, STS-3c, STS-6c, STS-9c, . . . , STS-45c, or STS-48c.
The pointer is validated according to Bellcore and ITU specifications. The H1/H2 pointers are used to determine
the location of the first path overhead (POH) byte (J1). The pointer interpreter consists of a finite state machine
(FSM) with four steady states. These states are defined as follows:
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The transition between states will require several consecutive events to protect against transient conditions caused
by bit errors during high BER conditions. The state machine is shown below in Figure 7.
The PT block monitors for the following conditions and takes appropriate actions:
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Normal state
Loss-of-pointer (LOP)
Alarm indication signal (AIS)
Concatenation
Pointer Increment. TDAT042G5 uses an 11-bit counter to count the number of pointer increments and updates
the associated counter holding register on the occurrence of PMRST (RPI_INC[A—D][10:0]; see register
description, page 198). A pointer increment can occur when in the normal pointer mode. The following two meth-
ods can be used to determine if the pointer increment operation should be performed: 6-of-10 or 8-of-10 majority
matching (selectable via software provisioning of register RINCDEC_6OR8MAJ [A—D]; see register description,
page 200).
(continued)
Figure 7. Pointer Interpreter State Diagram
NORMAL
LOP
3 CONC INDICATIONS
3 NORMAL POINTERS
8 INVALID POINTERS
1 NDF POINTER OR
3 AIS INDICATIONS
CONC
AIS
Agere Systems Inc.
Data Sheet
May 2001
5-7935(F)