IBM3009K2672
IBM SONET/SDH Framer
Transmit Higher-Order Path Termination (HPT) Layer Options
The SONET/SDH framer provides the HPT functions when the UTOPIA or the UTOPIA Level 2+ interface is
being used to interface PPP or ATM payloads. POH processing is not performed when the Telecom Bus is
used.
All POH bytes are stored in on-chip RAM where they are retrieved for transmission or for access by a micro-
processor. POH processing is provided for up to four SPE/VC-4s.
The J1 path trace can be written by the microprocessor into on-chip RAM (i.e., the transmit GRA) for trans-
mission as a 16-byte or 64-byte long message. The B3 is calculated for each frame and written into the on-
chip RAM for transmission. C2 bytes can be written to on-chip RAM by the microprocessor for transmission.
When an unequipped signal is transmitted by setting the HUG bit in the OT#Conf2 register, the transmitted
C2 and the C-4 payload section are forced to all ‘0’s. In this case, the C2 value in the corresponding transmit
GRA does not have an effect, but the other POH bytes in the transmit GRA do have an effect. Path FEBE is
based on received B3 errors and is automatically inserted into the transmit G1 byte. Path RDI generation per
[G.707] and [GR-253] are performed based on mode (SONET or SDH) as follows:
RDI Generation for Transmit HPT
Mode
Interrupt Request or Status Indication
Transmitted RDI Code1
Notes
HPAIS, LOP
101
110
010
001
101
110
010
001
UNEQ, HPTIM
SDH
SynchHunt (i.e., loss of cell delineation)
No defects
HPAIS, LOP
UNEQ, HPTIM
2
3
SONET (Bellcore)
SynchHunt (i.e., loss of cell delineation), SLM
No defects
1. Bit Number uses ITU-T and Bellcore bit numbering convention.
2. A control bit (TIM_RDI) is used to disable or enable the HPTIM interrupt request bit from causing Path RDI to be transmitted. This
bit should be set to disable HPTIM from causing a Path RDI to be transmitted.
3. A control bit (SLM_RDI) is used to disable or enable the SLM interrupt request bit from causing Path RDI to be transmitted.
ssframer.01
8/27/99
Operation
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