Contents Telektronikk - Telenor

146
Preliminary studies indicate that traffic
mixes where low capacity traffic competes
with high capacity traffic, do not
perform well. Either the connection
blocking will be unacceptably high for
the high capacity traffic or the link utilisation
will be unacceptably low. Routing
methods alone do not repair this, and we
have to use service protection methods
for best network utilisation with given
grade of service constraints. Also in these
cases the computational effort is small
when dimensioning according to an
equivalent bandwidth allocation model.
When the offered traffic grows, it may be
a good idea to separate the traffic in
classes with dedicated capacity pools in
the trunk group for each class and perhaps
a capacity pool for common overflow.
- Traffic with capacity demands of 5 –
10 % of the link capacity and more
may be treated separately, perhaps on a
reservation basis.
- It may be that we should also divide
the rest of the traffic in two classes, i.e.
traffic with capacity demands lower
than for instance 0.5 % of the link
capacity in one class, though this
depends on the traffic volume and the
traffic mix.
The provision of quality of service
classes, best effort services, variable bit
rate services with more complicated (non
linear) allocation schemes and various
ways of bundling virtual channel connections
into virtual path connections, will
complicate the dimensioning task. This is
a challenge for future research activities.
References
1 Aein, J M. A multi-user-class, blocked-calls-cleared,
demand access
model. IEEE transaction on communications,
Com 26, 3, 1978.
2 Delbrouck, L E N. On the steadystate
distribution in a service facility
carrying mixtures of traffic with different
peakedness factor and capacity
requirements. IEEE transaction on
communications, Com 31, 11, 1983.
3 Fiche, G, Le Gall, P, Ricupero, S.
Study of blocking for multislot connections
in digital link systems. I:
11th international teletraffic
congress, ITC-11.
4 Gehrst & Lee. Virtual-circuit load
control in fast packet-switched
broadband networks. Globecom
1988.
5 ITU-T Recommendation I.311. B-
ISDN general network aspects.
Geneva 1993.
6 ITU-T Recommendation I.356. B-
ISDN ATM layer cell transfer performance.
Geneva 1994.
7 Iversen, V B. A simple convolution
algorithm for the exact evaluation of
multi-service loss systems with heterogeneous
traffic flows and access
control. I: Proceedings of 7th Nordic
teletraffic seminar, NTS-7. Lund,
Sweden, 1987.
8 Kaspher, A N. Bandwidth allocation
and network dimensioning for international
multiservice networks. I:
Proceedings of 5th international teletraffic
congress, ITC-5, Lake Como,
1987.
9 Kaufmann, J S. Blocking in a shared
resource environment. IEEE transaction
on communications, Com 29, 10,
1981.
10 Labourdette & Hart. Blocking probabilities
in multitraffic loss systems:
insensitivity, asymptotic behaviour
and approximations. IEEE transactions
on communications, 8, 1992.
11 Lindberger, K. Some ideas on GOS
and call scale link-by-link dimensioning.
I: 10th Nordic teletraffic
seminar, NTS-10, Århus 1992.
12 Roberts, J. A service system with
heterogeneous user requirements.
Performance of data communications
systems and their applications, North
Holland, 1981.
13 Roberts, J W. Teletraffic models for
Telecom 1 integrated services network.
I: 10th international teletraffic
congress, ITC-10, Montreal 1983.