Side_1_360

are considered for a set of traffic flows. Such a

logical partition could be a certain amount of

transfer bandwidth, or a certain amount of the

buffering capacity. Furthermore, a set of re-

sources can be bundled and considered as a com-

ponent at a certain abstraction level. Such per-

spectives are likely in a traffic/network manage-

ment system. These resources are commonly

reflected in an objective function used to deter-

mine which configuration is the better one. For

network design costs of the resources are often

essential components in the objective function.

When calculating the overall cost of a network

deployment, several aspects should be assessed.

These include the routers, the transmission

capacity, any service handler, management sys-

tems, and so forth. Depending on the scope of

the study, some of these may be less relevant.

For example, when a network design is to be

found, aspects of management systems may not

be considered when these are not affected by the

resulting solution.

Both hardware and software related costs should

be taken into account. In several cases it is seen

by an operator that the basic hardware and soft-

ware come at a specified price, although up-

grading the functionality by introducing new

software packages would be relatively costly.

Such factors would be essential in a techno-eco-

nomic study, but again might be less relevant

during network design.

4.2 A Cost Model

When elaborating a cost model a basic assump-

tion is that sets of resources can be related to

certain groups of traffic flows. In particular this

is relevant for link/bandwidth capacity. Here

LSPs can be applied, possibly with capacity

reservation. Some measures of the required

capacity are then needed. For simplicity a single

measure is adopted, like the effective bandwidth

defined. This measure is assumed in the discus-

sion to follow. Other measures might also be

incorporated in the model/algorithm presented.

Figure 10 Components of the
cost model/objective function

Box A continued

Medium Application Degree of Data rate Key performance parameters and target values

symmetry

One-way delay Delay variation Information loss

Audio High quality Primarily 32–128 kb/s < 10 sec for < 1 msec < 1 % FER

streaming one-way

audio

Video One-way One-way 32–384 kb/s < 10 sec < 1 % FER

Data Bulk data Primarily < 10 sec N/A Zero

transfer/ one-way

retrieval

Data Still image One-way < 10 sec N/A Zero

Data Telemetry One-way < 28.8 kb/s < 10 sec N/A Zero

• monitoring

Table A-3 End user performance expectations – streaming services

Call handler

IP-level network

Control cost

Switching cost

Transmission cost