\chapter{Network Management Models}
\label{ch:nmm}

This chapter describes models that are used to structure the problems
and ideas in network management.  Section~\ref{sec:osi} studies the
OSI network management models, and section~\ref{sec:tmn} describes the
TMN network management model.  Management of customer networks is
briefly addressed in section~\ref{sec:cnm}.  SMART TMN, described in
section~\ref{sec:stmn}, has a broader scope on network management.
Finally, network management for the TINA architecture is studied in
section~\ref{sec:tina}.

\section{OSI Management}
\label{sec:osi}

The Open Systems Interconnection (OSI) Management is documented in
ITU-T and CCITT X.700-series Recommendations~\cite{a11}. It is based
on four components: \textit{Management Model, Information Model,
Communication Protocol for Transferring Management Information}, and
\textit{Systems Management Functions}. OSI Management functionality is
divided into five \textit{Management Functional Areas} according to
the \textit{OSI FCAPS model}~\cite{a2}.
%\begin{itemize}
%\item Management Model,
%\item Information Model,
%\item Communication Protocols for Transferring Management Information, and
%\item Systems Management Functions.
%\end{itemize}



\subsection{Management Model}
\label{manageragent}

The Management Model describes a manager-agent concept
(figure~\ref{fig:manageragent}). The manager system manages Managed
Objects in distributed manner by issuing remote management requests to
agent processes. The agents manage the Managed Objects and are
responsible for implementing the functionality needed to execute the
requests. They may also return values and send notifications (events
or traps generated by Managed Objects) back to the manager~\cite{a5,
a12, a18, rfc1095}.

\begin{figure}[htb]
\begin{center}
\epsfxsize1.0\textwidth
\epsfbox{kuvat/manager-agent}
\caption{The manager-agent concept~\cite{a27}}
\label{fig:manageragent}
\end{center}
\end{figure}

A network to be managed can be divided into management domains. A
domain is an administrative partition of a managed network or
Internet. Domains may be useful for reasons of scale, security, or
administrative autonomy. Domains allow the construction of both strict
hierarchical and fully cooperative and distributed network management
systems~\cite{rfc1095, a27}.


\subsection{Information Model}
\label{mib}
\label{managedobjects}

The information model deals with Managed Objects that are abstractions
of the real resources on the network~\cite{a2}.  All information
relevant to network management and definitions of the objects to be
managed resides in a Management Information Base (MIB). MIB is a
"conceptual repository of management information", an abstract view of
all the resources to be managed. All information within a system that
can be referenced by management protocol is considered to be part of
MIB~\cite{rfc1095}.

The logical structure of MIB and the conventions for describing and
uniquely identifying MIB information are defined in the Structure of
Management Information (SMI). SMI is defined in terms of Abstract
Syntax Notation One (ASN.1), that provides a machine-independent
representation for the information~\cite{rfc1095}.


\subsection{Communication Protocol for Transferring Management Information}

The transfer of management information in OSI networks is provided by
Common Management Information Protocol (CMIP, see
page~\pageref{sec:cmip})~\cite{a12}.
% The management operations and notifications are transferred using Common Management Information Protocol (CMIP)~\cite{a12}.

\subsection{Systems Management Functions}

Systems Management Functions (SMFs) define common facilities that can
be applied to particular Managed Objects corresponding to different
resources. The SMFs include mechanisms for controlling access to
Managed Objects and the distribution of events, common formats for
reporting alarms and status, and mechanisms for invoking and
controlling remote test execution~\cite{a18}.


\subsection{Management Functional Areas --- OSI FCAPS model}
\label{fcaps}

OSI Management functionality is divided into five management
functional areas~\cite{a12}:
\begin{itemize}
\item \textbf{Fault Management} encompasses fault detection, isolation
and the correction of abnormal operation. It includes functions to
maintain and examine error logs, accept and act upon error
notifications, trace and identify faults, carry out diagnostic tests
and correct faults. 

\item \textbf{Configuration Management} identifies, exercises control
over, collects data from and provides data to open systems. The
purpose of Configuration management is to prepare for, initialize,
start, provide the continuous operation of, and terminate
interconnection services. 
 
\item \textbf{Accounting Management} enables charges to be established
for the use of resources in OSI environment, and for costs to be
identified for the use of those resources. It includes functions to
inform users of costs incurred or resources consumed, to enable
accounting limits to be set and tariff schedules to be associated with
the use of resources and enable costs to be combined where multiple
resources are used. 

\item \textbf{Performance Management} offers functions to report and
evaluate the operation of network and it's elements. Statistical data
is collected for the analysis and development of the network. 

\item \textbf{Security Management} includes functions to create,
delete and control security services and mechanisms, distribute
security-relevant information, and report security-relevant events. 

\end{itemize}




\section{Telecommunications Management Network}
\label{sec:tmn}
\label{tmn}

A Telecommunications Management Network (TMN) provides management
functions for telecommunications network and services. It also offers
communications between itself and the network and it's services. It is
an architecture that provides interconnection between various types of
Operations Systems (OSs) and/or telecommunications equipment for the
exchange of management information~\cite{a17}.

The top-level standards and recommendations for OSI systems management
form the basis for TMN standards~\cite{a11}. The TMN standards are
defined in ITU-T M.3000-series documents~\cite[page~48]{a30}.


Figure~\ref{fig:tmn} shows a general relationship between a TMN and
the telecommunications network it manages. TMN is conceptually a
separate network that interfaces a telecommunications network at
several different points to send/receive information to/from it and to
control it's operations. A TMN may use parts of the telecommunications
network to provide it's communications~\cite{a17}.


\begin{figure}[htb]
\begin{center}
\epsfxsize1.0\textwidth
\epsfbox{kuvat/tmn}
\caption{General relationship of a TMN to a telecommunications network~\cite[page~25]{a30}}
\label{fig:tmn}
\end{center}
\end{figure}


\subsection{TMN Management services}

% TMN Management Services (TMN-MSs) provide operations, administration, maintenance, and provisioning (OAM\&P) support for a telecommunications network.
% A TMN supports management areas which cover the planning, installation, operation, administration, maintenance and provision of telecommunications networks and services~\cite{a30, a17}.

The scope of network management is broader in telecommunications than
in data communications. Thus a TMN must provide more than just the
functionality defined in the OSI FCAPS model.  TMN Management Services
(TMN-MSs) include Customer administration, Network provisioning
management, Workforce management, Tariff, charging and accounting
administration, Quality of Service and network performance
administration, Traffic measurement and analysis administration,
Traffic management, Routing and digit analysis administration,
Maintenance management, Security administration, and Logistics
management. An overview on TMN-MSs is provided in ITU-T Recommendation
M.3200. A more detailed description can be found in ITU-T
Recommendation M.3400.

A TMN Management Service is made up of TMN Management Function Set
Groups. They are further subdivided into Management Function Sets and
eventually into Management Functions. A TMN application of any
complexity can be created by combining these elementary building
blocks.  The management functions are then mapped to TMN Systems
Management (SM) services. The TMN SM services are provided by OSI
Systems Management Functions. These principles are illustrated in
figure~\ref{fig:tmnservices}. Figure~\ref{fig:tmnfunctionsets} shows
the mapping of OSI Management Functional Areas (MFAs) and TMN
Management Function Set Groups. The Management Function Sets and
individual Functions are defined in ITU-T Recommendation M.3400
~\cite[page~48--53]{a30}.
% TMN management functions are the most elementary building blocks, which can be combined in a modular manner to build TMN applications of any complexity


\begin{figure}[htb]
\begin{center}
\epsfxsize1.0\textwidth
\epsfbox{kuvat/tmn_services}
\caption{TMN Management Services, Management Functions and Systems Management Services~\cite[page~50]{a30}.}
\label{fig:tmnservices}
\end{center}
\end{figure}


\begin{figure}[htb]
\begin{center}
\epsfxsize1.0\textwidth
\epsfbox{kuvat/tmn_function_sets}
\caption{Mapping of OSI MFAs and TMN Management Function Set Groups~\cite[page~53]{a30}.}
\label{fig:tmnfunctionsets}
\end{center}
\end{figure}


\subsection{TMN Management Layers}
\label{tmnlayers}

The needed management functionality is achieved using five layers of
management, described in~\cite[pages~19--21]{a30}. Each layer has it's
own functions and interfaces to layers above and below. The lower
layers perform more specific functions and upper layers are concerned
with functions more general. Each layer must interact with the layer
below in order to execute it's task.

\textbf{Business management layer} is responsible for management at
the enterprise level. The layer is concerned with the network
planning, agreement with operators, and executive-level activities
such as strategic planning. 

\textbf{Service management layer} provides the customer
interface. It's functions include service provisioning, opening and
closing accounts, resolving customer complaints, fault reporting, and
maintaining data on Quality of Service. 

\textbf{Network management layer} manages the whole network. It
receives data from network element management layer and provides
total-network-level views. 

\textbf{Network element management layer} is responsible for managing
a subnetwork of the whole managed network. The interaction with
network elements is provided by network element layer. 

\textbf{Network element layer} provides for the agent functions of the
managed network elements. 


\subsection{TMN architecture}

% TMN architecture can vary from simple to complex. 
TMN architecture is divided into three aspects, which can be
considered separately when designing a TMN: \textit{functional,
information} and \textit{physical architecture}. \textbf{Functional
architecture} describes the appropriate division and distribution of
functionality within the TMN to allow the creation of building blocks,
from which a TMN of any complexity can be implemented~\cite{a17}.

\textbf{Information architecture} describes the nature of the
information that needs to be exchanged between the building blocks,
and also describes the understandings that each building block must
have about the information held in other building blocks~\cite{a17}. 

\textbf{Physical architecture} describes the implementation of
function blocks on physical systems and the interfaces between
them~\cite[page~31]{a30}. 



\section{Customer Network Management}
\label{sec:cnm}

The purpose of Customer Network Management (CNM) is to provide
external users of a telecommunications network with a limited control
and view of the managed network. It enables customers to manage a
portion of the whole network and subscribe it's
services. Figure~\ref{fig:cnm_architecture} illustrates the CNM
functional architecture~\cite[pages~38--42]{a30}.

\begin{figure}[htb]
\begin{center}
\epsfxsize.9\textwidth
\epsfbox{kuvat/cnm_architecture}
\caption{CNM functional architecture~\cite[page~39]{a30}.}
\label{fig:cnm_architecture}
\end{center}
\end{figure}


Customers are provided with a subset of the TMN management services,
limited management information, and \textit{CNM supporting
services}. CNM supporting services enable customer's management system
to request service provisioning and service usage from a service
provider~\cite[pages~38--44]{a30}.
% Figure~\ref{fig:cnm_services} presents the CNM services and mapping to the OSI Management Functional Areas~\cite[pages~38--44]{a30}.

%\begin{figure}[htb]
%\begin{center}
%\epsfxsize1.0\textwidth
%\epsfbox{kuvat/cnm_services}
%\caption{CNM services and mapping to the OSI Management Functional Areas~\cite[pages~38--44]{a30}.}
%\label{fig:cnm_services}
%\end{center}
%\end{figure}



\section{SMART TMN}
\label{sec:stmn}

Smart TMN~\cite{a6} is a program of Telemanagement Forum, a non-profit
organization of dozens of product vendors and operators.  The goal of
SMART TMN is to present a larger scale, business process-driven model
of telecommunications networks management.

The SMART TMN consists of four elements:
\begin{itemize}
\item \textbf{Telecommunications Operations Map (TOM)} which describes
key business processes, 

\item \textbf{Technology Integration Map}, which contains
recommendations of technologies to adopt for different management
applications~\cite{a7}, 

\item \textbf{Central Information Facility} for information store for
technical specifications, object models etc., and 

\item \textbf{Catalyst Projects}, which are projects to validate
technology concepts. 

\end{itemize}



\section{Telecommunications Information Networking Architecture}
\label{sec:tina}

Telecommunications Information Networking Architecture (TINA) is
designed to meet the needs of telecommunications services ranging from
traditional voice-based services to interactive multimedia,
multi-party services, information services, as well as management
services. All these services are considered to be software-based
applications that operate on a distributed computing
platform~\cite[page~137]{a13}. TINA addresses a wide range of issues
and provides a complex set of concepts and principles. In this
respect, it is much more a framework, a compilation of concepts and
principles for developing future distributed telecommunications and
management services, than a specific
architecture~\cite[page~148]{a13}.


\subsection{TINA architecture}

TINA architecture is based on four principles: Object-oriented
analysis and design, distribution, decoupling of software components
and separation of concern. The purpose of these principles is to
ensure interoperability, portability and re-usability of software
components, independence from technologies, and to help to create and
manage complex systems~\cite{a15}. The two major separations of
concern are the separation between applications and the environment,
and the separation of applications into the service specific part and
the generic management and control part~\cite{a15}.

Due to the complexity of TINA, it's architecture is divided into four
sectors: \textit{computing architecture, service architecture, network
architecture} and \textit{management
architecture}~\cite[page~24]{a14}.

The \textbf{computing architecture} defines a set of concepts and
principles for designing and building distributed
software~\cite{a14}. It is based on the Basic Reference Model for Open
Distributed Processing (RM-ODP, ITU Recommendation
X.900)~\cite[page~148]{a13}.

The \textbf{service architecture} defines a set of concepts and
principles for the design, specification, implementation and
management of telecommunication services~\cite[pages~25--26]{a14}.

The \textbf{network architecture} provides generic concepts that
describe transport network in general, technology-independent way. The
TINA network is a transport network that is capable of transporting
information that is heterogeneous in terms of data formats, bandwidth
and other quality of service related aspects. The network is capable
of handling streams and their point-to-point or multi-point
connections~\cite[page~26]{a14}.

The \textbf{management architecture} is based on the OSI management
and TMN standards. In particular, the management architecture adopts
the TMN functional layers. All the other TINA architectures are
influenced by the management architecture
principles~\cite[page~163]{a13}. The TINA management architecture is
still under study~\cite[pages~27--28]{a14}.


\subsection{TINA network management model}

TINA network management model extends the OSI FCAPS model (see
page~\pageref{fcaps})~\cite{a13,a16}. Configuration management is
divided into \textit{connection management} and
\textit{resource configuration management}.

\textbf{Connection management} is considered a fundamental activity in
telecommunications network~\cite{a14}. TINA represents a new approach
to the traditional way of connection control~\cite[page~163]{a13}:

Connection control includes the establishment, modification and
release of connections. Traditionally these are considered as control
operations, which are viewed as being different from management. In
TINA, these operations are seen as dynamic management
operations. Connection management is used by service architecture
components whenever a service requires connections.

\textbf{Resource configuration management} contains installation
support, provisioning of network resources to make them available for
use, monitoring and control of resource status. It also includes
management of the relationships among the resources.

\textbf{Fault management} includes alarm surveillance, fault
localization, fault correction, testing functions and trouble
administration information.

\textbf{Accounting management} is responsible for measuring and
establishing charges for the use of resources.







