Lanex TM-78 Operating manual - page 15
10Base-T/100Base-TX/E1 converter
Operating Manual
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IOA78-1C 10 January 2005
3.5. Quality management
Quality management refers to surveillance of transmissoin quality in line G.703/E1
ensured by the device, and to package transmission between LAN and WAN ports.
Quality surveillance between LAN and WAN ports consists in monitoring the transmitted
packages and registration of bad packages. Transmission quality assessment is the proportion of
the number of bad packages to all packages transmitted in the given time.
Quality surveillance of line E1/G.703 consists in recording quality-related transmission
events that can be used for assessing transmission and service quality according to G.826. The
following should be used as a basis of quality assessment:
• number of errored seconds - ES
• number of severely errored seconds - SES
• number of errored blocks – EB
• proportion of errored seconds to all seconds when the device is available – ESR [%]
• proportion of severely errored seconds to all seconds when the device is available – SESR [%]
• proportion of errored blocks to all blocks when the device is available – BBER [%]
• number of device availability seconds - AS
• number of device unavailability seconds – UAS, 10 consecutive SES change the line status to
unavailable, 10 seconds without SES restores the availability status
• total number of seconds of operations from the point of switching on the device – TS
AS value = TS – UAS
Table 3-3. Event table.
specifies the manner of interpretation of events from the receiving
direction for 2048 kbit/s signal.
Table 3-3. Event table.
Type of event per 1 second
Interpretatio
n
1 LOS - loss of signal at input
ES + SES
1 HDB3 code error
ES
1 LOF – loss of frame
ES + SES
1 AIS – alarm indication signal
ES + SES
10
-6
– error rate
ES
10
-3
– error rate
SES
1 FAS – errors in synchronization pattern
ES
28 FAS
ES + SES
1 CRC-4 – control sequence
ES
805 CRC-4
ES + SES
The number of events related to quality of threshold excess is counted in 15-minute and
24-hour cycles in registries located in the device.
The 15-minute logs form a stack of at least 16 logs of past periods. When all logs are full,
the contents of the oldest 15-minute cycle logs can be lost.
The operator can read and set thresholds for 15-minute and 24-hour logs. Quality
thresholds for a 15-minute cycle should be set in a range from 1 to 900, with the following
recommended default values: 120 for ES and 15 for SES. No threshold values are specified in
standards for the 24-hour cycle. Quality thresholds for the 24 h cycle should be set within a range
from 0 to 86400.
Device unavailability definitions are presented in Figure 3-3.