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 or service meets the needs of the subscriber and operator. The process can be tailored according to each new network or service.
Planning methodology process
- business planning
- long-term and medium-term network planning
- short-term network planning
- IT asset sourcing
- 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 role of forecasting
During the process of Network Planning and Design, estimates are made of the expected traffic intensity and traffic load 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.
- Definition of problem;
- Data acquisition;
- Choice of forecasting method;
- Documentation and analysis of results.
The dimensioning process involves determining the network’s topology, routing plan, traffic matrix, and GoS requirements, and using this information to determine the maximum call handling capacity of the switches, 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 protocols.
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 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.
The available technologies for traffic engineering include MPLS and ATM for current Internet backbone. For example, MPLS allows carriers to provision LSPs with dynamic or explicit routes. The dynamic routes is controlled by CSPF while the explicit routes are optimized in an offline tool or through a path computation element which is under study by IETF. Fast reroute has been implemented by major vendors, such as Cisco and Juniper Networks, to provide localized resilient capability for MPLS networks. End-to-end protection is an alternative resilient approach. It provisions a backup route for each primary route. Pre-planning enough bandwidth for these backup routes is one of the active aproach for survivable network design.
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 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.