Bridging
2-84 SONET Port Configuration
¥Errored SecondsÑThe counter associated with the number of Errored
Seconds, or Far-End Errored Seconds, encountered by a SONET/SDH Path in
the speciÞed interval.
An Errored Second (ES) is a second with one or more coding violations (bit
parity errors) at the associated layer reported at the Section, Line, or Path layer
of the SONET link, or a second during which at least one or more incoming
defects (e.g., Loss of Signal, Loss of Pointer, or Loss of Frame) has occurred at
that layer. Coding Violations are Bit Interleaved Parity (BIP) errors that are
detected in the incoming signal (as described below).
¥Severely Errored SecondsÑThe number of Severely Errored Seconds, or
Far-End Severely Errored Seconds, encountered by a SONET/SDH Path in the
speciÞed interval.
A Severely Errored Second (SES) is a second with X or more coding violations
(bit parity errors) reported at the Section, Line, or Path layer of the SONET link,
or a second during which at least one or more incoming defects (e.g., Loss of
Signal, Loss of Pointer, or Loss of Frame) has occurred at that layer. The
statistic provided in this Þeld is provided by the STS-Path level of the link.
Values of X at each layer depend on the linkÕs line rate and the Bit Error Rate.
For the STS-Path layer, with a line rate of 51.84 Mbps (STS-1) and a BER of 1.5
x 10-7, X is 9; with a line rate of 155.52 Mbps (STS-3) and a BER of 1 x 10-7, X is
16.
If the FE100-Sx or APIM-2x is experiencing consecutive Severely Errored
Seconds, it may indicate an impending period of network unavailability
(which begins at the onset of 10 consecutive SESs). Periods of unavailability
can severely impact service (e.g., the disconnection of switched services).
Availability is restored at the onset of 10 consecutive error-free seconds.
¥Severely Errored Framing SecondsÑThe counter associated with the number
of Severely Errored Framing Seconds encountered by a SONET/SDH Section
in the speciÞed interval. A Severely Errored Framing Second (SEFS) is a second
containing one or more SEF events. This counter is only counted at the Section
Layer, and is not available as a Far-End counter.
¥Code ViolationsÑThe number of Coding Violations (CVs) encountered by a
SONET/SDH Path interface, or the number of Far-End Coding Violations
reported via the far-end block error count to the monitored SONET/SDH Path
interface, in the speciÞed interval.
Coding Violations are Bit Interleaved Parity (BIP) transmission errors that are
detected in the incoming signal. Bit Interleaved Parity is a check at the
receiving interface that groups all bits in a block into a unit (e.g., a byte), then
veriÞes the block for parity for each bit position in the group by making sure
that the number of bits set to the value Ô1Õ is either even or odd, as reported by
the transmitting entity.