tdat04622 ETC-unknow, tdat04622 Datasheet - Page 84

• Manufacturer Part Number: tdat04622
• Description: Tdat Sonet/sdh 155/622/2488 Mbits/s Data Interfaces
• Manufacturer: ETC-unknow

TDAT042G5 SONET/SDH
155/622/2488 Mbits/s Data Interface
Functional Description
Overhead Processor (OHP) Block
Receive OHP (continued)
Figure 6 illustrates the parameters used in determining the bit error detection rate.
TDAT042G5 provides a method to monitor the BER at the line and path layers. The following explains the algo-
rithm for this method to set and clear the BER. The algorithm for this method is the same for setting and clearing
the BER, the only difference is the programmed values. TDAT042G5 includes two complete sets of identical
counters, one used to determine signal fail (SF) and one used to determine signal degrade (SD). The only differ-
ence between SF and SD is the provisioned values. The same algorithm is used for both the line and path layers of
SONET.
The algorithm uses four sets of counters: labelled Ns (number of frames), L (number of errors), M (number of
errored blocks), and B (total number of blocks). Each of these counters has different values that are provisioned to
either set the BER high or clear the BER indication. The algorithm works by counting blocks, i.e., a preset number
of SONET/SDH frames (Ns). If the number of errors in the block exceeds the provisioned level (L), then the errored
block counter is incremented by 1; otherwise, the number of blocks in error stays at its current level. At this point,
the frame counter and the error counter are reset back to 0 and start counting again. At the end of a preset number
of blocks (B), the count in the errored block counter is compared against a provisioned threshold (M). If the total
number of blocks in error equals or exceeds the provisioned threshold (M), then the BER alarm is raised. If the total
number of blocks in error is less than the provisioned amount (M), then the BER alarm is cleared.
The values used by the counters are determined by the state of the algorithm. If the BER state is low, then the SET
parameters are used. If the BER state is high, then the CLEAR parameters are used.
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NUMBER OF FRAMES IN A MONITORING BLOCK SFNSSET[A—D] OR SDNSSET[A—D],
NUMBER OF MONITORING BLOCKS SFBSET[A—D] OR SDBSET[A—D] (IN THIS CASE, 3)
BOUNDARY
FRAME
Figure 6. Signal Degrade and Failure Parameters for BER
SFLSET[A—D] OR SDLSET[A—D]
SFLCLEAR[A—D] OR SDLCLEAR[A—D]
ACCUMULATED BIP ERROR COUNT:
B1 OR B2 FOR LINE
B3 FOR PATH
(continued)
(continued)
BOUNDARY
BLOCK
SFNSCLEAR[A—D] OR SDNSCLEAR[A—D]
(IN THIS CASE, 7)
SFMSET[A—D] OR SDMSET[A—D]
SFMCLEAR[A—D] OR SDMCLEAR[A—D]
BLOCK GOOD/BAD COUNT
Agere Systems Inc.
Data Sheet
May 2001
5-7934(F)