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Post-installation network measurements 167
In subsequent design cycles, review and refine the QoS objective, based
on data collected from intranet QoS monitoring.
Having decided on a set of QoS objectives, then determine the planning
threshold. The planning thresholds are based on the QoS objectives.
These thresholds are used to trigger network implementation decisions
when the prevailing QoS is within range of the targeted values. This
gives time for implementation processes to follow through. The planning
thresholds can be set 5% to 15% below the QoS objectives, depending on
the implementation lag time.
Intranet QoS monitoring
To monitor one-way delay and packet loss statistics, install a delay and route
monitoring tool, such as PING and Traceroute on the TLAN subnet of each
IP Trunk 3.01 (and later) site. Each delay monitoring tool runs continuously,
injecting probe packets to each ITG site about every minute. The amount of
load generated by this is not considered significant. At the end of the month,
the hours with the highest one-way delay are noted; within those hours, the
packet loss and standard deviation statistics can be computed.
See "Measure intranet QoS" (page 140) for information about
implementation of the PING hosts and the use of scripting.
See "Obtain QoS measurement tools" (page 144) for information about
where to obtain other more specialized delay and route monitoring tools.
At the end of the month, analyze each site’s QoS infor mation. Table 35
"QoS monitoring" (page 167) provides a sample.
Table 35
QoS monitoring
One-way delay
Mean+σ (ms)
Packet loss
Mean+σ (%) QoS
Site pair
Last
perio
d
Current
period
Last
perio
d
Current
period
Last
perio
d
Current
period
Objecti
ve
Santa Clara/
Richardson
135 166 1 2
Excel
lent
Good Excellent
Santa Clara/
Ottawa
210 155 3 1
Good Excellent Excellent
Declines in QoS can be observed through the comparison of QoS between
the last period and current period. If a route does not meet the QoS
objective, take immediate action to improve the route’s performance.
Nortel Communication Server 1000
IP Trunk Fundamentals
NN43001-563 01.01 Standard
Release 5.0 30 May 2007
Copyright © 2007, Nortel Networks
.