\chapter{Introduction}

Networks and distributed processing systems have become critical factors in the business world. Companies and organizations develop large and complex networks with an increasing number of applications and users. The need for high capacity IP networks is growing because of the new WWW and multimedia applications, faster data transmission in mobile networks, and IP telephony. Today's routed IP networks suffer from serious problems related to scalability, manageability, reliability and cost.

Helsinki University of Technology has started IPMAN project in 1999. The target of the IPMAN project is to research and develop a network management paradigm for massive IP-networks.


\section{Changes in network management}

Introduction of new equipment and new technologies means introduction of new information systems, which also increases the number of data repositories and fault management systems. As networks become larger and more complex, tools and applications to ease network management are critical. Automated network management is needed~\cite{b24}.

Time is a critical factor in network management (see figure~\ref{fig:networkmanagement}). Managers strive for shorter cycles and customers demand faster response. Shorter cycles lead into lower costs and greater productivity~\cite{b16}. Effective use of network facilities can improve a competitive position, create new market opportunities and afford efficient communications between business units and customers.

\begin{figure}[htb]
\begin{center}
\epsfxsize.7\textwidth
\epsfbox{kuvat/network_management}
\caption{Network management, modified~\cite{b16}}
\label{fig:networkmanagement}
\end{center}
\end{figure}

Network management views the computing environment as a collection of co-operating systems connected by various communication mechanisms. Sun Microsystems expresses that the network is the computer. This means that effective system management is thinking the network as a single, multilayer entity, one that requires its own care~\cite{b18}. An important aspect is that management is useless to a company if it does not solve business problems and ease the work of operators~\cite{b27}.

A recent Gartner Group study "Strategies to Control Distributed Computing's Exploding Costs" reports that while the strategic value of systems and networks continues to increase, the escalating cost of managing that technology is undermining the organization's expected return on its investment~\cite{b16}.

Network management that is effective and adapts to business strategy requires:
\begin{itemize}
\item The right abstraction level of information,
\item Information at the right time, and
\item Information in an easy-to-use format~\cite{b16}.
\end{itemize}

Effective network management that adapts to business strategy contains functions, such as technology selection, network automation, capacity planning, predictive problem avoidance and sophisticated trouble-shooting. These functions all require information that goes beyond the data available to most of network management staff.


\section{Future trends}

Experts forecast the changes that will happen in the next years. According to James Herman in the Sixth IFIP/IEEE International Symposium on Integrated Network Management (May 1999): "The main affect of the Internet is to enable the rise of virtual business and services. There will also be large data volumes (more customers $\times$ more interactions with customers $\times$ more data per interaction = an explosion). PC will no longer be the dominant access device, the network is the center of everything. There will be more need for mobile and wireless infrastructure. Data will find you wherever you are. When there are no connectors, it means lighter, cheaper and simple devices."

Figure~\ref{fig:internet} expresses the vision of Internet development. Almost every telephone company has become involved in delivering non-telephone services to end users. Plain Old Telephone Service (POTS) is the basic telephone call service. Internet Access Provider's (IAP's) role is to ensure that the end user has a reliable connection to the Internet.

Most cable television (CATV) providers are interested in offering telephone and Internet services as well as video-on-demand services. The Hybrid Fiber-Coax (HFC) network is an emerging cable architecture for providing residential video, voice telephony, data, and other interactive services to end users over fiber optic and coaxial cables. The HFC network can provide the bandwidth that some multimedia applications require, using the spectrum from 5 MHz to 450 MHz for conventional downstream analog information, and the spectrum from 450 MHz to 750 MHz for digital broadcast services such as voice and video telephony, video-on-demand, and interactive television.

An alternative to a coaxial or fiber/coaxial network is offered by a technology that can transmit relatively high-speed data over untwisted or twisted pair cables for distances up to 4000 m. The technology can use existing digital telephone subscriber lines. The High bit-rate Digital Subscriber Line (HDSL) offers bi-directional transmission at 1.5 Mbps with a transmission bandwidth of 200 kHz. Asymmetric Digital Subscriber Line (ADSL) can transmit four one-way 1.5-Mbps video signals, in addition to a full-duplex 384-Kbps data signal, a 16-Kbps control signal, and analog telephone service. ADSL has a transmission bandwidth of 1.1 MHz.

Many end users want to access services not only in their homes, but also outside the homes. Wireless transmission enables the desired mobility among users. Because the bandwidth is shared, users are grouped into small cells. The users in each cell communicate with a single base station, and base stations are linked together by a wired network.

Mobile Ad hoc Networking (MANET) is an autonomous system of mobile nodes, where a node is both a host and a router. Mobile nodes communicate via wireless technology, and they are free to move randomly and organize themselves arbitrarily. MANET supports robust and efficient operation in mobile wireless networks by incorporating routing functionality into mobile nodes.

Satellite transmission also facilitates mobility. Because the transmission area covered by a satellite is very large, it is well suited for video and audio broadcasting~\cite[pages 16--20]{b3}.

\begin{figure}[htb]
\begin{center}
\epsfxsize.6\textwidth
\epsfbox{kuvat/internet}
\caption{The Internet picture~\cite{b6}}
\label{fig:internet}
\end{center}
\end{figure}


\section{Structure of this document}

Chapter~\ref{ch:nmm} studies models developed to classify and order network management problems. Chapter~\ref{ch:nmp} describes some protocols used for network management, and chapter~\ref{ch:future} covers some possible future trends in network management.

Professor Olli Martikainen suggested use of a reference model, where network management is divided into four levels (see figure~\ref{fig:refmodel}).

\begin{figure}[htb]
\begin{center}
\epsfxsize.35\textwidth
\epsfbox{kuvat/ref_model}
\caption{Reference model by Professor Olli Martikainen}
\label{fig:refmodel}
\end{center}
\end{figure}

IPMAN project has developed further the reference model, and has modified its structure (see figure~\ref{fig:modified}).

\begin{figure}[htb]
\begin{center}
\epsfxsize.5\textwidth
\epsfbox{kuvat/martikainen}
\caption{Modified reference model}
\label{fig:modified}
\end{center}
\end{figure}

Chapters~\ref{ch:network} to~\ref{ch:contents} study each layer of the reference model. Finally, chapter~\ref{ch:commercial} gives a short summary of commercial network management tools.
