EXFO FTB/IQS-85100G Packet Blazer for FTB-500/IQS-600 - Manual (Page 303)

Test Functions
Packet Blazer 293
OH - SONET/SDH

F1
1
: User/User Channel. This byte is reserved for user purposes.

D1
1
, D2
1
, and D3
1
: Data Communications Channel (DCC). Provides a
192 Kbit/s data communication between two STEs for operation
functions such as OAM&P.
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.
1. This byte is only defined for the first STS-1/STM-1 frame of a composite signal.
SS Bits Description
00 SONET
01 Undefined
10 SDH
11 Undefined