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Network planning and design is an iterative process, encompassing topological design, network-synthesis, and network-realization, and is aimed at ensuring that a new
telecommunications network A telecommunications network is a group of nodes interconnected by telecommunications links that are used to exchange messages between the nodes. The links may use a variety of technologies based on the methodologies of circuit switching, message ...
or service meets the needs of the subscriber and operator.>Penttinen A., ''Chapter 10 – Network Planning and Dimensioning, Lecture Notes: S-38.145 - Introduction to
Teletraffic Teletraffic engineering, telecommunications traffic engineering, or just traffic engineering when in context, is the application of transportation traffic engineering theory to telecommunications. Teletraffic engineers use their knowledge of stat ...
Theory'', Helsinki University of Technology, Fall 1999.
The process can be tailored according to each new network or service.>Farr R.E., ''Telecommunications Traffic, Tariffs and Costs – An Introduction For Managers'', Peter Peregrinus Ltd, 1988.


A network planning methodology

A traditional network planning methodology in the context of business decisions involves five layers of planning, namely: * need assessment and resource assessment * short-term network planning * IT resource * long-term and medium-term network planning * operations and maintenance./> Each of these layers incorporates plans for different time horizons, i.e. the business planning layer determines the planning that the operator must perform to ensure that the network will perform as required for its intended life-span. The Operations and Maintenance layer, however, examines how the network will run on a day-to-day basis. The network planning process begins with the acquisition of external information. This includes: * forecasts of how the new network/service will operate; * the economic information concerning costs, and * the technical details of the network’s capabilities./> /> Planning a new network/service involves implementing the new system across the first four layers of the
OSI Reference Model The Open Systems Interconnection model (OSI model) is a conceptual model that 'provides a common basis for the coordination of SOstandards development for the purpose of systems interconnection'. In the OSI reference model, the communications ...
./> Choices must be made for the
protocol Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technology ...
s and transmission technologies./> /> The network planning process involves three main steps: * Topological design: This stage involves determining where to place the components and how to connect them. The (
topological In mathematics, topology (from the Greek words , and ) is concerned with the properties of a geometric object that are preserved under continuous deformations, such as stretching, twisting, crumpling, and bending; that is, without closing h ...
) optimization methods that can be used in this stage come from an area of mathematics called
Graph Theory In mathematics, graph theory is the study of ''graphs'', which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of '' vertices'' (also called ''nodes'' or ''points'') which are conne ...
. These methods involve determining the costs of transmission and the cost of switching, and thereby determining the optimum connection matrix and location of switches and concentrators./> * Network-synthesis: This stage involves determining the size of the components used, subject to performance criteria such as the
Grade of Service In telecommunication engineering, and in particular teletraffic engineering, the quality of voice service is specified by two measures: the grade of service (GoS) and the quality of service (QoS). Grade of service is the probability of a call in a ...
(GOS). The method used is known as "Nonlinear Optimisation", and involves determining the topology, required GoS, cost of transmission, etc., and using this information to calculate a routing plan, and the size of the components./> * Network realization: This stage involves determining how to meet capacity requirements, and ensure reliability within the network. The method used is known as "Multicommodity Flow Optimisation", and involves determining all information relating to demand, costs, and reliability, and then using this information to calculate an actual physical circuit plan./> These steps are performed iteratively in parallel with one another./> />


The role of forecasting

During the process of Network Planning and Design, estimates are made of the expected
traffic intensity In telecommunication networks, traffic intensity is a measure of the average occupancy of a server or resource during a specified period of time, normally a busy hour. It is measured in traffic units ( erlangs) and defined as the ratio of the time ...
and
traffic load Traffic comprises pedestrians, vehicles, ridden or herded animals, trains, and other Public conveyance, conveyances that use public ways (roads) for travel and transportation. Traffic laws govern and regulate traffic, while rules of the roa ...
that the network must support./> If a network of a similar nature already exists, traffic measurements of such a network can be used to calculate the exact traffic load. /> If there are no similar networks, then the network planner must use
telecommunications forecasting All telecommunications service providers perform forecasting calculations to assist them in planning their networks.Farr R.E., Telecommunications Traffic, Tariffs and Costs – An Introduction For Managers, Peter Peregrinus, 1988. Accurate forecast ...
methods to estimate the expected traffic intensity./> The forecasting process involves several steps:/> * Definition of a problem; * Data acquisition; * Choice of forecasting method; * Analysis/Forecasting; * Documentation and analysis of results.


Dimensioning

Dimensioning a new network determines the minimum capacity requirements that will still allow the
Teletraffic Grade of Service In telecommunication engineering, and in particular teletraffic engineering, the quality of voice service is specified by two measures: the grade of service (GoS) and the quality of service (QoS). Grade of service is the probability of a call in a ...
(GoS) requirements to be met./> /> To do this, dimensioning involves planning for peak-hour traffic, i.e. that hour during the day during which traffic intensity is at its peak./> The dimensioning process involves determining the network’s topology, routing plan, traffic
matrix Matrix most commonly refers to: * ''The Matrix'' (franchise), an American media franchise ** ''The Matrix'', a 1999 science-fiction action film ** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...
, and GoS requirements, and using this information to determine the maximum call handling capacity of the
switches In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of ...
, and the maximum number of channels required between the switches./> This process requires a complex model that simulates the behavior of the network equipment and
routing protocol A routing protocol specifies how routers communicate with each other to distribute information that enables them to select routes between nodes on a computer network. Routers perform the traffic directing functions on the Internet; data packets ...
s. A dimensioning rule is that the planner must ensure that the traffic load should never approach a load of 100 percent./> To calculate the correct dimensioning to comply with the above rule, the planner must take on-going measurements of the network’s traffic, and continuously maintain and upgrade resources to meet the changing requirements./> /> Another reason for overprovisioning is to make sure that traffic can be rerouted in case a failure occurs in the network. Because of the complexity of network dimensioning, this is typically done using specialized software tools. Whereas researchers typically develop custom software to study a particular problem, network operators typically make use of commercial network planning software.


Traffic engineering

Compared to network engineering, which adds resources such as links, routers, and switches into the network, traffic engineering targets changing traffic paths on the existing network to alleviate traffic congestion or accommodate more traffic demand. This technology is critical when the cost of network expansion is prohibitively high and the network load is not optimally balanced. The first part provides financial motivation for traffic engineering while the second part grants the possibility of deploying this technology.


Survivability

Network survivability enables the network to maintain maximum network connectivity and quality of service under failure conditions. It has been one of the critical requirements in network planning and design. It involves design requirements on topology, protocol, bandwidth allocation, etc.. Topology requirement can be maintaining a minimum two-connected network against any failure of a single link or node. Protocol requirements include using a dynamic routing protocol to reroute traffic against network dynamics during the transition of network dimensioning or equipment failures. Bandwidth allocation requirements pro-actively allocate extra bandwidth to avoid traffic loss under failure conditions. This topic has been actively studied in conferences, such as the International Workshop on Design of Reliable Communication Networks (DRCN).


Data driven network design

More recently, with the increasing role of Artificial Intelligence technologies in engineering, the idea of using data to create data-driven models of existing networks has been proposed. By analyzing large network data, also the less desired behaviors that may occur in real-world networks can be understood, worked around, and avoided in future designs. Both the design and management of networked systems can be improved by data-driven paradigm. Data-driven models can also be used at various phases of service and network management life cycle such as service instantiation, service provision, optimization, monitoring, and diagnostic.An Architecture for Data Model-Driven Network Management: The Network Virtualization Case
IETF draft.


See also

* Network Partition for Optimization


References

Planning and design Telecommunications engineering