Nortel Meridian 1 Description, Installation And Operation page 75

IP Telecommuter Engineering Guidelines Page 75 of 262
When an intranet takes on a real-time service, the users of that service will
impose additional QoS objectives in the intranet; some of these targets may
be less stringent compared with those imposed by current services, while
other targets would be more stringent. For intranets not exposed to real-time
services in the past but which now need to deliver IP Telecommuter traffic, it
is likely that the QoS objectives pertaining to delay will impose an additional
design constraints.
One approach is to simply subject all intranet traffic to additional QoS
constraints, and design the network to the strictest QoS objectives, essentially
a "best-of-breed" solution. This for example would improve the quality of
data services, even though most applications may not perceive a reduction of
say 50ms in delay. Improving the network results in one that would be
adequately engineered for voice, but over-engineered for data services.
Another approach is to consider using QoS mechanisms in the intranet, the
goal of which is to provide a more cost-effective solution to engineering the
intranet for non-homogenous traffic types. Unfortunately IP QoS
mechanisms are still a relatively recent technology, infrequently
implemented on intranets, and it is difficult to predict the consequences.
This section outlines the QoS mechanisms that can work in conjunction with
the IP Line card node, and the intranet-wide consequences if implemented.
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Traffic mix is the mix of IP Telecommuter traffic and data traffic on the
intranet.
Before implementing QoS mechanisms in the network, the technician needs
to assess the traffic mix of the network. QoS mechanisms depend on the
process and ability to distinguish traffic (by class) so as to provide
differentiated services.
If an intranet is designed solely to deliver IP Telecommuter traffic, and all
traffic flows are equal priority, then there is no need to consider QoS
mechanisms. This network would have only one class of traffic.
ITG Line 1.0/IP Telecommuter Description, Installation and Operation