The main discussion area in this article is about network design. As
Information and Communication Technology (ICT) is going to be the main pillar
for any organization, the business success of an organization is driven by the
successful implementation of ICT. Here ICT includes not only the development of
software for various activities of an organization, but the underlying support
of the computer network. The software helps the organization to process information
and will help with strategic decisions. When software, like ERP, processes huge
data to give various insights into information, the main concern is the storage
of this large data. Also, there is a need to think about designing a disaster
recovery site. The success of ICT implementation is when commuting and
communication go hand in hand. Twenty years back, computer networking was about
connecting computers so that users were able to share files or printing devices
or other network resources. Computer networking is not limited to connection,
rather it extends to networking application, bandwidth and reliability of
network. This chapter is about a recap of basic networking concepts keeping in
mind about the design perspective of the networks, Later sections cover the
network design methodology.
Network
Based on the area covered by the network, the network can be classified into Local Area Network (LAN), Metropolitan Area Network (MAN) and Wide Area Network (WAN). They differ from each other based on three categories viz. size, transmission technology and topology.
Local Area Network (LAN)
Local Area Network (LAN) refers to the network spread across a building
or a campus. It is used to share resources and exchange information across less
than 500 interconnected devices. Sharing of information, resources and network
services reduces the cost of the network. Information can be easily exchanged
across an organization using LAN. Since LANs are restricted in size,
transmission time across the network can be known well in advance. Knowing this
limitation makes the network management simpler and easier.
The transmission technology used for LANs may be a Token Ring
network, Fiber Distributed Data Interface (FDDI) network or Ethernet. Star, bus
and ring are commonly used topologies for designing LAN. IEEE 802.3 defines LAN
access methods using CSMA/CD.
The design of LAN is for an organization within a single building or within a single campus. In a broad sense, only one transmission technology will be considered for the entire LAN or utmost two will be considered. For example, Ethernet IEEE 802.3 or IEEE 802.11x. More focus will be on designing a network to support application requirement, centralized storage of files, access of cloud-based applications and design of Demilitarized zone to protect public servers of the organization.
Metropolitan Area Network (MAN)
Metropolitan Area Network (MAN) refers to the network across a
metropolitan city such as Delhi, Mumbai, etc. It spans across a city and has a
larger area than LAN. MAN connects two or more local area networks situated in
the same city. For example, MAN might be used to connect various branches of an
organization in a single city. MAN can be completely owned and operated by a
private company. Thus, it proves to be the backbone for large networks. MAN
uses Distributed Queue Dual Bus (DQDB) or the IEEE 802.6 standard which enables
data transmission in both directions simultaneously. MAN is widely used to
connect banks, universities and colleges. Therefore, designing of MAN is
extending the private network across multiple ?it’s of an organization. Here,
all design considerations of LAN need to be considered along with the design of
the backbone network to support multiple sites. A strategy for designing
reliable backup and storage site is also created. As multiple sites of an organization
in a city are working on different administrative aspects of an organization,
heterogeneous connectivity at the operating system level also needs to be
considered. For example, single sign-on mechanism across sites or access of
data from servers of different OSS etc. Also, the network should support the
integration of various applications across multiple sites seamlessly.
Wide Area Network (WAN)
Wide Area Network (WAN) refers to the network spanning across
multiple cities, countries or continents. It uses long distance carriers
whereas the protocols and equipment are the same as used in MAN. Internet is
the best example of WAN. International banks across several countries are
connected through WAN. It might be a group of MANs, LANs or both. If a WAN is
specifically owned by a large, private company, it is better known as Enterprise
Network. One or more Internet Service Providers can be used to offer network
services such as the Internet, asynchronous transfer mode and frame relay. It
is slower and less reliable than LAN. WAN utilizes many media for
communication, such as cables, fiber, telephone lines, satellite and airwaves.
Since it covers a large geographical area, setting up a WAN is an expensive,
time-consuming and complicated task. Once a WAN is set up, network supervisors
and technicians are required to maintain the network. Security is undoubtedly a
major concern when people from different verticals access information from
devices connected through WAN. Security against hackers and viruses, apart from
malicious users, is much required. For a mid-sized organization, the design of
efficient and secure Virtual Private Network (VPN) to connect multiple offices
across the city is a challenging task. For that, the Routing strategy for
implementation of Software Defined Network across multiple sites needs to be
considered.
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