Implementing Quality Of Service In Ip Networks - Nortel Remote Office 9150 Installation And Administration Manual

Network engineering guidelines
Implementing Quality of Service in IP
networks
Introduction
Today's corporate intranets are developed because of the need to support data
services, for which a "best effort" IP delivery mechanism usually suffices.
Standard intranets are designed to support a set of QoS objectives dictated by
these data services.
Setting Quality of Service objectives
When an intranet takes on a real-time service, the users of that service impose
additional QoS objectives in the intranet. Some of these targets can be less
stringent compared with those imposed by current services, while other targets
are more stringent. For intranets not exposed to real-time services in the past but
that now need to deliver Remote Office traffic, it is likely that the QoS objectives
pertaining to delay will impose an additional design constraint on the intranet.
Method 1
One approach is to simply subject all intranet traffic to additional QoS
constraints, and to design the network to the strictest QoS objectives. This is
essentially a "best-of-breed" solution. This, for example, improves the quality of
data services, even though most applications might not perceive a reduction of
50 ms in delay. Improvements to the network result in one that is adequately
engineered for voice, but over-engineered for data services.
Method 2
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
relatively new, hardly implemented on intranets, and difficult to predict the
consequences.
416
Standard 1.0
Remote Office 9150