Nortel Remote Office 9150 Installation And Administration Manual page 433

March 2000
If the intranet capacity is tight and the Remote Office traffic is significant, you
should consider making intranet measurements under load. Load can be applied
using traffic generator tools. The amount of load should match the Remote
Office traffic estimated in "Remote Office traffic engineering" on page 375.
Obtaining Quality of Service measurement tools
The ping and traceroute commands are standard IP tools that are usually
included with a network host's TCP/IP stack. You can find a survey of QoS
measurement tools and packages (including commercial ones) on the home page
of the Cooperative Association for Internet Data Analysis (CAIDA) at http://
www.caida.org. Some of these are delay monitoring tools that include features
like timestamping, plotting, and computation of standard deviation.
Determining if the intranet meets expected Remote Office Quality of
Service
At the end of this measurement and analysis, you should have a good indicator
whether the corporate intranet as it stands can deliver adequate voice and fax
services. To gauge the QoS level for each site pair, see the "Expected QoS level"
column on page 406.
In order to offer voice and fax services over the intranet, you should keep the
network within a good or excellent QoS level at the Mean+σ operating region.
You should not offer fax services on routes that have only fair or poor QoS
levels.
If the expected QoS levels of some or all routes fall short of being good, you
must evaluate the options and costs for upgrading the intranet. You can estimate
the amount of one-way delay that needs to be reduced to raise the QoS level.
"Fine-tuning the network Quality of Service" on page 408 provides guidelines
for reducing one-way delay. Often this involves a link upgrade, a topology
change, or implementation of QoS in the network.
You can decide to keep costs down, and accept a temporary fair QoS level for a
selected route. In that case, having made a calculated trade-off in quality, you
need to carefully monitor the QoS level, reset expectations with the end users,
and be receptive to user feedback.
Installation and Administration Guide
Network engineering guidelines
407