Proprietary TranSwitch Corporation Information for use Solely by its Customers
DATA SHEET
BLOCK DIAGRAM DESCRIPTION
Transmit And Receive Paths, Overhead Communications, Alarms And Control
L3M
TXC-03452B
A simplified block diagram of the L3M device is shown in Figure 1. The portion of the ITU-T SDH multiplexing
structure implemented by the L3M device is shown in Figure 2. In the Transmit direction, positive/negative
(P/N) rail data and clock input signals, or NRZ data and clock input signals, operating at 44.736 Mbit/s (DS3) or
34.368 Mbit/s (E3), are connected to the Input Block. The transmit line input consists of positive rail/NRZ signal
lead (TPOS), negative rail signal lead (TNEG), and input clock (TCLK). A control bit is provided in software that
inverts the clock signal if required. The Input Block performs either an HDB3 or B3ZS decoder function if the
input line termination is a rail signal. Separate NRZ data (RNRZD) and clock (RNRZC) output signals are pro-
vided for external performance monitoring circuits. Illegal coding violations are counted in a 16-bit performance
counter. When the line termination is NRZ, the negative rail signal lead (TNEG) can be used to clock in an
external loss of signal indication. The transmit signal and clock are both monitored for operation, and alarms
are reported for failure conditions. Control bits are provided that enable the L3M device to send a line AIS when
either signal or clock failure is detected. The Input Block also monitors the line signal for an E3 AIS and it has a
2
15
-1 or 2
23
-1 pseudo-random binary sequence (PRBS) test generator for testing.
X
N
STM-N
AUG
X
1
AU-4
VC-4
ITU-T SDH multiplexing structure
C-4
L3M Portion
X
3
X
3
X
1
TUG-3
X
7
AU-3
VC-3
VC-4
TU-3
VC-3
139264 kbit/s
(Note 1)
L3M
Same as STS-3
44736 kbit/s
or 34368 kbit/s
(Note 1)
C-3
X
7
TUG-2
Pointer processing
Multiplexing
Aligning
Mapping
X
1
TU-2
X
3
X
4
TU-12
VC-12
C-12
VC-2
C-2
6312 kbit/s
(Note 1)
2048 kbit/s
(Note 1)
TU-11
VC-11
C-11
1544 kbit/s
(Note 1)
Note 1: G.702 tributaries associated with containers C-x are shown. Other signals (e.g., ATM) can also be accommodated.
Figure 2. L3M Multiplexing Structure
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TXC-03452B-MB
Ed. 6, April 2001
ETC [ ETC ]
