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Cabinet distribution over a data network Page 179 of 544
Option 11C and 11C Mini Technical Reference Guide
Based on system configured thresholds, the level of service will be derived
and reported to the craftsperson with the PRT QOS <cab#> command in LD
117. See Administration (553-3001-311) and Maintenance (553-3001-511).
Data Network Ratings (Excellent, Good, Fair, Poor) along with the actual
parameter values for network delay are displayed in Table 56.
The values in Table 56 assume that there is no echo cancellation mechanism
and no particular mechanism for recovering lost packets.
The command PRT PDV <cab#> in LD 117 displays both the current size of
the PDV buffer and the number of PDV underflows.
In addition, a warning message is printed when a parameter threshold (or
combination of thresholds) is reached. These thresholds are not user
configurable.
In LD 117, the command CHG PDV <port#> <delay> is used to set Packet
Delay Variation (PDV buffer size) on a per link basis. The <delay> parameter
can take values from 0.5 ms to 8 ms. This value should be initially tested at
default settings. Increase the <delay> parameter value by 0.5 ms increments
if an unacceptable level of voice quality is experienced (“pops and clicks”).
Decrease this value if echo is experienced. The goal is to operate with the
smallest buffer possible.
The PDV buffer size for each IP connection is configured at the Main and is
automatically downloaded to the IP Expansion cabinet.
Table 56
Campus data network voice quality measurements
Voice QoS Rating
Network Round Trip
Delay
(PDV Max 7.8 ms)
Network Round Trip
Delay
(PDV Min 0.5 ms)
Network Packet
Loss
Excellent <5 ms <12 ms <0.5%
Good 5 - 25 ms 12 - 32 ms 0.5 - 1%
Fair 25 - 45 ms 32 - 52 ms 1 - 1.5 ms
Poor >45 ms >52 ms >1.5%