CCNA Complete Guide 2nd Edition.pdf - Cisco Learning Home

Loss of Signal Triggered upon observing 175 +/- 75 contiguous pulse positions
with no pulses of either positive or negative polarity for T1 lines;
or when more than 10 consecutive 0s are detected for E1 lines.
Code Violation Error The CRC value in the received frame does not match with the
corresponding locally calculated CRC value.
Bipolar Violation Occurs when 2 mark signals (1s) occur in sequence with the same
polarity (when not part of a B8ZS substitution). T1 signaling
specifies that each mark must be the opposite polarity of the one
preceding it. It also includes other error patterns such as 8 or more
consecutive 0s and incorrect parity.
Errored Second A second with one or more Code Violation Error or Loss of
Frame events have occurred. The presence of Bipolar Violations
also triggers an Errored Second. Some errored seconds may occur
on a normal circuit.
Severely Errored Second A second with 320 or more Code Violation Error or Loss of
Frame events have occurred. Also known as Extreme Errored
Second (EES).
Unavailable Second A second that the CSU is in the Unavailable Signal state,
including the initial 10 seconds to enter the state, but excluding
the 10 seconds to exit the state.
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