Telektronikk 2/3.2001
1 Introduction
A network operator faced with supporting a
range of services and users and being intercon-
nected with other operators and providers, would
seek ways of automating its procedures. These
procedures must support efficient operation of
the network while still being open for adapting
services to individual users. The Traffic Engi-
neering activities provide means for doing this.
Introducing principles from the policy apparatus
does further allow for effective mechanisms as
more conditions can be considered during the
service delivery.
The main objectives of this paper are to de-
scribed challenges and some solutions for inter-
connecting domains and principles of policy as
described by IETF. Chapter 2 illustrates the
interconnection challenges in a wider scope.
Some issues on the IP level and on other levels
are described in Chapter 3 and Chapter 4,
respectively. Chapter 5 addresses the introduc-
tion of policy, by describing the basic ideas as
elaborated by IETF.
2 Interconnecting Domains
When interconnecting IP-based networks, sev-
eral “levels” could be considered as illustrated in
Figure 1. That is, in addition to the exchange of
IP packets, interactions between management
systems, service control handlers, and on the
business level are expected. These have also to
be considered when arranging interconnection
configurations between an operator and its
neighbouring actors.
On the IP level, arrangements for mapping
between packet handling in the two domains
have to be settled. For instance, in case of two
DiffServ domains, different service classes may
be defined and it must be agreed how these
relate to each other. Exchange of routing infor-
mation must also be agreed, like the use of rout-
ing protocols and which metrics to exchange.
The Service Level Agreements (SLAs) are
attached to the business relations, although refer-
ring to Service Level Specifications (SLSs) on
Traffic Engineering
– Inter-domain and Policy Issues
TERJE JENSEN
An essential complication when managing a network is the interconnections with other operators. This
implies that the operator does not have control over the complete path, but depends on conditions in the
connected networks. A further challenge is to introduce more automatic and accurate service provision,
possibly adapted to individual customers and following the conditions in the network. Some means for
achieving these goals are treated in this paper.
Figure 1 Interconnecting domains
Terje Jensen (39) is Research
Manager at Telenor R&D,
Kjeller. He earned his PhD
degree in 1995 from the Norwe-
gian University of Science and
Technology. Activities include
performance modelling and
analysis, dimensioning and net-
work evolution studies.
[email protected]
SLA
SLA
Xu
SLA
G1 CR1 G2
CR
G2 CR G1
CR
End-user
access
End-user
access
Management
system
Management
system
Service
provider
Service
provider
Xu
Xm
Xn
Xnu Xnu
Legend
ISP: Internet Service Provider
Xn : Network to network interface
G1: Edge Router (or Gateway)
CR: Core Router
Xnu: User-network interface
SLA: Service Level Agreement
Xm: ISP to ISP management interface
G2: Border Router (or Gateway)
Xu: ISP to User management interface
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