
Agere Systems Inc.
53
Data Sheet
May 2001
155/622/2488 Mbits/s Data Interface
TDAT042G5 SONET/SDH
Functional Description
(continued)
SONET Framer
The SONET framer consists of the overhead processor (OHP) and path terminator (PT) blocks. The receive
SONET framer requires 625
μ
s to drop frame after the line input signal is lost. Once a valid receive line input is
restored, the maximum average reframe time (MART) is 250
μ
s.
Overhead Processor (OHP) Block
The OHP block terminates/generates the section and line overhead bytes of the line. The data rate of the TOH
interface is given in Table 14. Timing for the TOH interface is given in the Interface Timing Specifications section
(see Table 172 and Table 173, page 271).
Table 14. R/T TOH Interface Rates
* This STS-48/STM-16 interface is a four-line interface resulting in an effective interface rate
of 82.944 Mbits/s.
All receive transport overhead bytes are output on the RTOH interface for external processing. Transmit transport
overhead bytes can optionally be inserted from the TTOH interface.
The transmit transport overhead bytes can be inserted in one of three ways selected through software provision-
ing: (1) automatically by hardware, (2) via software provisioning, or (3) through the TOAC. Table 15 defines those
overhead bytes that can be inserted via each of the three paths. In some cases, the user has the choice to insert
the byte via software registers or through the TOAC. Superscripts in the table reference these insertion methods
which are described in the footnotes.
Table 15. TOAC Byte Insertion: An STS-3/STM-1 Example
1.Inserted via TOAC, but not part of SONET standard.
2.Inserted via software or automatically via hardware.
3.Inserted via TOAC only.
4.Inserted via software register only.
5.Inserted via TOAC or software register.
6.Inserted via TOAC hardware; should be included in TOAC interface timing.
Mode
R/T TOH Interface Rate
STS-48/STM-16
STS-12/STM-4
STS-3/STM-1
20.736* Mbits/s
20.736 Mbits/s
5.184 Mbits/s
OH Parity
3
(1st bit of
1st byte)
X
6
D1
3
X
6
X
6
D4
3
D7
3
D10
3
S1
5
X
6
X
6
X
6
X
6
X
6
J0
5
Z0
4
Z0
4
B1-2
1
D1-2
1
X
6
X
6
D4-2
1
D7-2
1
D10-2
1
Z1-2
3
B1-3
1
D2-3
1
X
6
X
6
D4-3
1
D7-3
1
D10-3
1
Z1-3
3
E1
5
D2
3
X
6
K1
2
D5
3
D8
3
D11
3
Z2
3
E1-2
1
D2-2
1
X
6
K1-2
1
D5-2
1
D8-2
1
D11-2
1
Z2-2
3
E1-3
1
D2-3
1
X
6
K1-3
1
D5-3
1
D8-3
1
D11-3
1
X
6
F1
5
D3
3
X
6
K2
2
D6
3
D9
3
D12
3
E2
3
F1-2
1
D3-2
1
X
6
K2-2
1
D6-2
1
D9-2
1
D12-2
1
E2-2
1
F1-3
1
D3-3
1
X
6
K2-3
1
D6-3
1
D9-3
1
D12-3
1
E2-3
1