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1 Introduction

It is confirmed by several sources that the

growth in the Internet has been phenomenal.

This is counted both in volume of traffic and

number of connected users and hosts/sites. The

Internet together with the mobile services may

not see any cases of comparable growth rate in

the industrial countries. However, not to forget

that telephony networks are also intensively de-

ployed in several parts of the world. However,

the Internet Protocol (IP) is entering into both

mobile networks and voice networks. This is

for example observed by IP being the current

longer-term solution for the 3rd generation

mobile systems and work on finding suitable

configurations for providing telephony over IP.

It may therefore be claimed that IP works as a

common “glue” between the applications and the

underlying infrastructure, see Figure 1. Applica-

tions are the functions towards the end-user,

such as a human being. Infrastructure is the

underlying functions such as cabling.

However, it should be observed that much work

is being carried out to find efficient configura-

tions and mechanisms built around IP. This can

be referred to as IP++, including the portfolio of

functionality promoted, e.g. for routing, resource

handling, traffic control, multicast, and so forth.

Looking at several major operators one sees that

a consolidation of networks is strived for. A

portfolio of any larger operator includes PSTN/

ISDN, X.21 networks, X. 25 networks, ATM

network, Frame Relay networks, and others.

Arriving at fewer networks is considered a better

configuration, taking into account the economy

of scale and scope. However, it also raises sev-

eral challenges, preserving the mechanisms for

differentiating between traffic flows, e.g. accord-

ing to their characteristics, level of payments of

the customers.

Tuning IP++ to work as a common layer for a

range of applications is not a straightforward

task. Therefore, several projects related to multi-

service IP-based networks have been initiated.

In addition to the technical challenges, there are

also others for example in the area of business

modelling, regulatory, property rights, etc. The

latter are not considered to any extent in this

issue of Telektronikk, but should not go unno-

ticed.

Within certain limits, one may say that arriving

at more predictable services is one of the main

goals of the IP-related work. This is also

addressed by the IP++, and addressed in accom-

panying papers of this Telektronikkissue. Pre-

dictability is not to be understood in a restricted

Network Principles and Applications

TERJE JENSEN

Although the IP-based networks are said to have inherent features that differ from the “traditional”

telecommunication networks, there are quite a lot of similarities. This paper points out the similarities

by elaborating on generic capabilities being present in all wide area networks. However, the IP

“specifics” are also included. These are more directed on routing and the use of IP in relation with other

protocols and systems. In particular, relations with optics, mobility and multicasting are discussed. The

Web and support of the Virtual Private Network and telephony services are also described.

Figure 1 IP ++ as the common “glue” for carrying traffic flows from different applications

over different infrastructure types

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]

IP++

applications

infrastructure

traffic

engineering

MPLS

end-to-end

intserv

cost efficient constraint-based

traffic characterisation routing

difserv

SLA

Telektronikk 2/3.2001