Meridian Nortel 1 Option 11C Technical Reference Manual page 179

Table 56
Campus data network voice quality measurements
Voice QoS Rating
Excellent
Good
Fair
Poor
Cabinet distribution over a data network
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.
Network Round Trip
Delay
(PDV Max 7.8 ms)
<5 ms
5 - 25 ms
25 - 45 ms
>45 ms
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.
Network Round Trip
Delay
(PDV Min 0.5 ms)
<12 ms
12 - 32 ms
32 - 52 ms
>52 ms
Option 11C and 11C Mini
Page 179 of 544
Network Packet
Loss
<0.5%
0.5 - 1%
1 - 1.5 ms
>1.5%
Technical Reference Guide