Side_1_360

(Dana P.) #1
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
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