EXFO FTB-1, User Manual

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Test Functions
NetBlazer
489
OH - SONET/SDH

F1 : User/User Channel. This byte is reserved for user purposes. This
byte is only defined for the first STS-1/STM-1 frame of a composite
signal.

D1
,
D2
, and
D3
: Data Communications Channel (DCC). Provides a
192 Kbit/s data communication between two STEs for operation
functions such as OAM&P. These bytes are only defined for the first
STS-1/STM-1 frame of a composite signal.
Transport OH - Line/MS

H1 and H2 : Pointer.
SONET: H1 and H2 bytes are combined to form a pointer indicating
where the path overhead begins within each SPE.
SDH: H1 and H2 bytes are combined to form a pointer indicating where
the VC (Virtual Container) frame begins within each SPE.
Bits 5 and 6 of the H1 byte represent the SS bits and are configurable as
follows.

H3 : Pointer Action. H3 is an extra byte used to compensate for the SPE
timing variation. The H1 and H2 pointer tell the receiver when the H3
pointer is used.
SONET: This byte must be defined in every STS-1 to STS-n frame of a
composite signal.
SDH: This byte must be defined in every STM-1 of an STM-N signal in
the event of negative justification, otherwise it is not defined.
SS Bits Description
00 SONET
01 Undefined
10 SDH
11 Undefined