
Configuring WAN Line Services
7-8 117021-A Rev. A
Setting the MCE1 Line Coding
E1 uses bipolar format for signals. In bipolar format, alternating positive and
negative pulses on the digital line signify the number one, and the absence of a
pulse signifies zero (refer to Figure 6-2 in Chapter 6). A long string of zeros on a
E1 line would cause the line to lose synchronization due to lack of pulses.
Bay Networks provides a line coding mechanism to maintain synchronization.
By default, the MCE1 interface uses high-density bipolar (HDB3) line coding.
You can select the alternate mark inversion (AMI) line coding instead.
HDB3 line coding replaces a block of eight consecutive binary 0s with an 8-bit
HDB3 code containing bipolar violations in the fourth and seventh bit positions of
the substituted code. In the receive direction, the HDB3 code is detected and
replaced with eight consecutive binary 0s.
AMI line coding is also bipolar: a binary 0 is transmitted as zero volts and a
binary 1 is transmitted as either a positive or negative pulse, opposite in polarity to
the previous pulse. When configured for AMI line coding, the MCE1 port remains
synchronized upon receiving up to 45 consecutive 0s.
Set the line coding for this MCE1 interface.
Setting the Alarm Threshold Time
By default, the MCE1 interface waits 2 seconds before logging a performance
defect or anomaly as an event message. Change that time, the alarm threshold, to
any value from 2 to 10 seconds for this MCE1 interface.
Setting the Alarm Threshold Clear Time
By default, the clear time for performance failure conditions is 2 seconds. If the
defect or anomaly clears within this time interval, MCE1 records a
performance-cleared condition and logs an event message. Change the alarm
threshold clear time to any value from 2 to 10 seconds for this MCE1 interface.
Site Manager: Line Coding parameter: page A-24
Site Manager: Setup Alarm Threshold (seconds) parameter: page A-24
Site Manager: Clear Alarm Threshold (seconds) parameter: page A-25
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