EXCEPTIONS specifies the exceptions that may
occur if any of the pre- or postconditions de-
scribed above are not fulfilled, with reference
to the RAISED_EXCEPTIONS clause.
6 Conclusion
A protocol neutral network level model address-
ing the topological aspects of IP networks on the
basis of the architectural components subnet-
work, link and connection point group has been
developed. This paper starts out analysing two
QoS-aware network architectures. It carries on to
provide an informal description of the topology
model, and also presents an abstract traffic
model for DiffServ-over-MPLS networks. The
modelling methodology, an enhanced version of
the Reference Model for Open Distributed Pro-
cessing, is briefly described in Section 3. The
functionality of the formal model is described
next and finally, as an example, the Enterprise,
Information and Computational Viewpoint spec-
ifications for the deletion of a topological link
are presented.
This model is most useful in representing the
geographical distribution of IP network re-
sources, partly to support the dissemination of
topological information in QoS-aware networks.
As previously mentioned, a number of func-
tional elements such as queueing, scheduling
and shaping are candidates for inclusion in
a more detailed version of the model.
A model for setting up LSP tunnels in DiffServ-
over-MPLS networks via a management inter-
face has been developed already [genIPmodel]
providing the basis for the server layer support
of the IP layer in a layered model. Extensions to
accommodate VPNs and Multicast will be con-
sidered.
7 References
[ASN.1] ITU-T. 1994. Abstract Syntax Notation
One (ASN.1): Specification of Basic Notation.
Geneva 07/94. (ITU-T rec.X.680.)
[G.805] ITU-T. 1995. Generic functional archi-
tecture of transport networks.Geneva 11/95.
(ITU-T rec. G.805.)
[G.851.1] ITU-T. 1999. Management of the
transport network – Application of the RM-ODP
framework.Geneva 03/99. (ITU-T rec. G.851.1.)
[G.852.2] ITU-T. 1999. Management of trans-
port network – Enterprise viewpoint description
of transport network resource model.Geneva,
03/99. (ITU-T rec. G.852.2.)[G.853.1] ITU-T. 1999. Management of trans-
port network – Common elements of the infor-
mation viewpoint for the management of a trans-
port network. Geneva, 03/99. (ITU-T rec.
G.853.1.)[GenIPmodel] Henriksen, T et al. 2000. A
generic model for IP based networks.Kjeller,
Telenor R&D. (R&D report R 39/2000.)[ITUmeth] Henriksen, T. 2001. Network level
modeling in ITU. Telektronikk, 97 (1), 147–155.[OOsw] Meyer, B. 1997. Object oriented soft-
ware construction.Upper Saddle River, NJ,
Prentice Hall.[PASTE] IETF. 1998. A provider architecture
for differentiated services and traffic engineer-
ing (PASTE). (RFC2430.)[RessHandlIP] Svinnset, I et al. 2001. Resource
handling in IP networks.Kjeller, Telenor R&D.
(R&D report R 5/2001).[TE_REQ] IETF. 1999. Requirements for traffic
engineering over MPLS.(RFC2702.)[X.901] ITU-T. Basic reference model for Open
Distributed Processing – Part 1: Overview.
Geneva. (ITU-T rec. X.901.)[X.902] ITU-T. Basic reference model for Open
Distributed Processing – Part2: Foundations.
Geneva. (ITU-T rec. X.902.)[X.903] ITU-T. Basic reference model for Open
Distributed Processing – Part 3: Architecture.
Geneva. (ITU-T rec. X.903.)[X.904] ITU-T. Basic reference model for Open
Distributed Processing – Part 4: Architectural
Semantics.Geneva. (ITU-T rec. X.904.)[Zintro] Potter, B et al. 1992. An introduction to
formal specification and Z.New York, Prentice
Hall.