Design an implementation of a network is a complex process involving many factors and technologies which is aimed at balancing the interests of different stakeholders and different constraints. There are three areas which should be covered in network design: developing the concept of a network, its implementation and review (Abels & Klein & Boyce, 2008). The goals of designing a network concept are to ensure scalability of the network, adaptability and adherence to cost limitations (Stallings, 2007). Scalability is the characteristics of a network which allows to serve the needs of a growing number of users without making significant changes to the network; adaptability means the ability of the system to integrate new devices and technologies without making radical changes to basic structure (Stallings, 2007). Finally, the control of costs should be based on the strategic needs of the company or project, and should address short-term and long-term perspectives as well as maintenance costs and perspective for growth.
The process of network design includes the following steps (Abels & Klein & Boyce, 2008):
- Evaluation of availability requirements and costs
- Selection of topologies and technologies
- Analysis of network workload
- Simulation of network behaviour
- Tests of network sensitivity
- Adjustment of network design basing on the tests
The purpose of this paper is to consider the costs of implementing LAN, MAN, WAN and ATM networks, and to describe the effectiveness of using Ethernet LAN and Extranet based on WAN for organizational needs.
Types of Networks
Basing on the geographical location of the network and its size, it is possible to distinguish between LAN, MAN and WAN networks (Fitzgerald & Dennis, 2008). LAN (local area network) is commonly understood as a group of computers within the same building or closely located buildings (within an area of no more than 2 km in distance). These networks are mostly private, and operate on speeds from 10MBps to 100 MBps, and sometimes even up to 1000 MBps (based on Gigabit Ethernet equipment) (Fitzgerald & Dennis, 2008). Major topologies for LAN are Ethernet and Token Ring, and the most commonly used transmission medium is wired cable (sometimes also coaxial cable). Logical topology of LAN network is commonly Bus or Ring (Fitzgerald & Dennis, 2008).
The next network type is MAN – metropolitan area network. These networks may cover several buildings, a district or even the whole city. MAN networks are commonly based on wireless technologies/RadioEthernet or optical fiber connection, operating on medium and high rates of throughput (Stallings, 2007). MAN networks can be either private or publicly owned, and often have means of including local networks into the structure. MAN networks might cover up to 50 km in diameter, and main transmission devices to create a MAN are modems and wired switches/routers.
A larger type of network is WAN (wide area network) which can connect different towns, cities, areas or even continents with each other. Internet is the bright example of a WAN. WAN networks include other types of networks as their elements; these networks are most often publicly owned or organized by ISP’s, and might use all types of connection as well as leased lines to create a connection between segments (Fitzgerald & Dennis, 2008). Among commonly used transmission devices for WAN there are public telephone networks, satellites and radio connections.
Comparison of network types is presented in Table 1.
Parameter LAN MAN WAN
Implementation costs Moderate cost Moderate to high cost High cost
Maintenance costs Low to moderate cost Low to moderate cost Moderate to high cost
Scalability Low Medium High
Adaptability Low to medium Medium High
Coverage Up to 2 km Up to 50 km Virtually unlimited
Type of topology Bus/Ring ATM, DQDB ATM, SoNET, Frame Relay
Example of such network Office network, PCs located in the same building; network is based on NIC adapters in the computers and connected by switches into a LAN Bank of administrative departments with offices in different parts of the city; public telephone lines are used, connection is done through modems and routers/bridges Company branches over the whole country; linked through satellite connections or VPN networks over Internet; each department has own LAN connected to the WAN
Table 1. Comparison of network types and their main characteristics (Horak, 2007)
There are four common physical technologies/standards that are used to implement networks: wired cable (UTP/STP), fiber optic cabling and ATM (Stallings, 2007). Currently, wireless networking options such as Wi-Fi and Radioethernet have been added (Abels & Klein & Boyce, 2008). Wired cabling is used for smaller networks (LAN and sometimes MAN) and is vulnerable to environmental conditions, electromagnetic fields, weather etc (Horak, 2007). Fiber optic cabling is significantly more stable with regard to environmental sensitivity, and currently it is one of the best alternatives for MAN and WAN networks (Stallings, 2007). Despite high installation costs, maintenance costs of fiber networks are rather low and reliability is high.
ATM (asynchronous transfer mode) technology evolved for phone lines and fiber networks; its small cell size allows to transmit video and multimedia data over the network, and to enable QoS during transmission (Abels & Klein & Boyce, 2008). ATM advantages are flexible allocation of bandwidth and simple routing. However, the cost of ATM networks is higher than IP-based networks (Ethernet).
Comparison of high-speed ATM and Ethernet costs is presented in Table 2.
Technology Speed Wired cable + network card + network port Fiber optic+network card + network port Network adapter card Network device port (e.g. switch)
ATM-48 2500 MBps Not necessary $55,000 sm Not necessary $28,000 sm
Gigabit Ethernet 2000 MBps $400-$1,200 $1,700-$2,600 SX mm
$3,850-$5,000 LX mm
$12,000 LX sm $150 (wired)
$550 (fiber mm)
$1,750 (fiber sm) $700 (wired)
$1,450 (SX mm)
$2,500 (LX mm)
$9,000 (LX sm)
Table 2. Comparison of Ethernet and ATM costs (Ultra Spec Cables Overview, 2011)
For the case of an organization managing an Ethernet LAN which is not cost effective and/or had not been appropriately tested for speed, cost, and quality, there can be different methods of solutions. If the organization is not planning to develop a MAN in future, upgrade to Gigabit Ethernet technology can be recommended, if the devices have appropriate potential (Hens & Caballero, 2008).
Since it is stated that this organization network type is LAN, this means that its area occupies no more than 2 km in diameter, and in order to optimize the networking costs, it can be appropriate to implement a wireless network based on IEEE 802.11g (or 802.11n, if high speeds are required) standard (Horak, 2007). This measure would be more effective than making corrections to the existing network and implementing device upgrades. However, the decision also should include the needs of scalability and reliability. While the suggested wireless network will provide greater reliability, this might not be scalable, and it would be difficult to transform LAN into MAN for this organization.
If the company is planning growth in future and requirements to the throughput are high, it would be appropriate to use private or leased phone lines, based on ATM technology, and develop a LAN which would be potentially transformed into a MAN. Table 2 shows the comparison of costs for ATM and Gigabit Ethernet network. Although the costs of implementing ATM-based network are several times higher, its impressive scalability and quality of connection will most probably give an economic effect in future. If the strategic partners of the organization created and managed a cost effective Extranet using WAN, then for the organization it would be most efficient to adopt this structure and join this WAN.
In order to design an optimal network, it is necessary to consider environmental limitations, constraints of performance and networking factors. Environmental limitations include the number of computers in the network, the number of hosts and servers as well as their locations, the distances which should be covered by the network and projected traffic/costs for the particular environment. Performance constrains are the necessary bandwidth, reliability of the network and parameters of host computers. Finally, networking factors include the chosen topology, available capacities of lines and time of delivery of packets (Hens & Caballero, 2008). The task is to balance the reliability/availability of the network and costs. Clients generally focus at network response time, reliability and throughput. Companies, from their side, have limitations based on available connection lines, IT budget and business factors such as potential growth, links with strategic partners and desire for scalability. Several variants of solution differing on the possible combinations of these factors for the chosen organization were suggested. Optimal choice can only be done, if exact requirements of all stakeholders, budget allocation and the company’s strategy are known.
Abels, E.G. & Klein, D.P. & Boyce, B.R. (2008). Business Information: Needs and Strategies. Emerald Group Publishing.
Fitzgerald, J. & Dennis, A. (2008). Business Data Communications and Networking. John Wiley and Sons.
Hens, F.J. & Caballero, J.M. (2008). Triple play: building the converged network for IP, VoIP and IPTV. John Wiley and Sons.
Horak, R. (2007). Telecommunications and data communications handbook. Wiley-Interscience.
Stallings, W. (2007). Data and computer communications. Prentice Hall.
Ultra Spec Cables Overview. (2011). Available from http://store.ultraspec.us