ort8850 Lattice Semiconductor Corp., ort8850 Datasheet - Page 29

• Manufacturer Part Number: ort8850
• Description: Field-programmable System Chip Fpsc Eight-channel X 850 Mbits/s Backplane Transceiver
• Manufacturer: Lattice Semiconductor Corp.

Lattice Semiconductor
Figure 13. SONET Overhead Bytes
When used in true SONET applications, most TOH bytes would be generated in the FPGA logic or by an external
device. The TOH bytes have the following functions. Table 9 and Table 10 show how the Embedded Core modifies
these bytes in the transmit direction and Table 12 shows how the bytes are modified in the receive direction.
Section Overhead Bytes:
• A1, A2 - These bytes are used for framing and to mark the beginning of a SONET frame. A1 has the value 0xF6
• C1/J0 - Section Trace Message - This byte carries the section trace message. The message is interpreted to ver-
• B1 - Section Bit Interleaved Parity (BIP-8) byte - This byte carries the parity information which is used to check for
• E1 - Section orderwire byte - This byte carries local orderwire information, which provides for a 64 Kbits/s voice
• F1 - Section user channel byte - This byte provides a 64 Kbits/s user channel which can be used in a proprietary
• D1, D2, D3 - Section Data Communications Channel (SDCC) bytes - These bytes provide a 192 Kbits/s channel
Line Overhead Bytes:
• H1, H2 - STS Payload Pointers (H1 and H2) - These bytes are used to locate the start of the SPE in a SONET
• H3 - Pointer Action Byte (H3) - This byte is used during frequency justifications. When a negative justification is
and A2 has the value 0x28.
ify connectivity to a particular node in the network.
transmission errors in a section. The computed parity value is transmitted in the next frame in the B1 position. It
is defined only for the first STS-1 of a STS-N signal. The other bytes have a default value of 0x00 if using serial
TOH insertion. In transparent TOH mode the other bytes are passed through from DINxx bus.
channel between two Section Termination Equipment (STE) devices.
fashion.
for transmission of information across STEs. This information could be for control and configuration, status mon-
itoring, alarms, network administration data etc.
frame. These two bytes contain the offset value, in bytes, between the pointer bytes and the start of the SPE.
These bytes are used for all the STS-1 signals contained in an STS-N signal to indicate the individual starting
positions of the SPEs. They bytes also contain justification indications, concatenation indications and path alarm
indication (AIS-P).
Overhead
Overhead
Section
Line
0
1
2
3
4
5
6
7
8
S1/Z1
D10
A1
B1
D1
H1
B2
D4
D7
0
Overhead
Transport
29
D11
D2
H2
D5
D8
A2
E1
K1
Z3
1
C1/J0
D12
D3
H3
K2
D6
D9
E2
F1
2
Overhead
ORCA ORT8850 Data Sheet
Path
G1
G1
B3
B3
C2
C2
H4
H4
F2
F2
Z4
Z4
Z5
Z5
Z6
Z6
J1
J1