To make a network survivable it must be heterogeneous. The functionality of this network is defined by a set of protocols and its operations. In heterogeneous networks, if a protocol is weakened by any attack, it will not affect the entire network. Applying this heterogeneity concept, a new survivability paradigm is described in this chapter. This network architecture improves the network's heterogeneity without losing its interoperability. Several issues discovered in security and survivability applications can be converted into scheduling problems. To overcome this, a new model is described to support design and analysis with security and survivability concerns. A five-step model is introduced to transmute applications into model abstraction and representations with solutions resulting from scheduling algorithms. A reverse transformation converts the solutions back to the application domain.
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Several computers are connected with one another to communicate with each other to form a computer network. The reason for this assembling or to form as a network is to share the resources among the interconnected computers. Various hardware and software technologies are utilized to build computer networks. Various kinds of hardware components like optical fiber, Ethernet or just utilizing wireless connections can also be used to form a network. The regular and generally utilized hardware component to build any network is the Ethernet. The network is formed with the help of Ethernet by linking discrete computer components with one another through wiring. Bridges, switches, hubs and routers are some of the different components to be utilized for the Ethernet networks. At the same time, various kinds of cables like coaxial cable, twisted pair wire and fiber optics also are used in the formation of Ethernet network.
Unlike wired networks, physical connection or wiring is not required in the formation of wireless networks. Signals of infrared and radio are utilized for communication process in the wireless technology. According to the literature of wireless technologies, many variations exist. For instance, Bluetooth, cellular systems, satellites, wireless LANs, terrestrial microwaves, etc. Even though initially, wireless technologies are not well established when compared to Ethernet, later they are well developed and made simple to work with. Yet the focal points and economy connected with the physical systems can't be disregarded completely. The topology of the network is the structure of the network formed by either wireless connections or physical connections among the nodes in the network. The requirements of the network determine the topology of the network. Hence, there will be various kinds of topologies.
Various kinds of computer networks include Local Area Network (LAN), Personal Area Network (PAN), Campus Area Network (CAN), Wide Area Network (WAN), Metropolitan Area Network (MAN), and Storage Area Network (SAN). To establish a network in small areas like a single building or individual labs in the colleges, Local Area Network (LAN) is best suitable. High data rate at Giga bits is offered by LANs in a small range. Personal Area Networks (PAN) is intended for personal uses and the corresponding range of communication is approximately 20 to 30 feet. CAN is a network which is larger when compared to LAN. When the computer systems in various locations need to be connected, then CAN is useful. For instance, the systems in administrative office, library, labs and other offices of the university can be connected to form CAN. Wide Area Networks (WAN) is formed from the compound connections among numerous LANs. It can be termed as interconnection of networks. For instance: Internet. Now-a-days, Internet is being used in almost every place like houses, commercial buildings, colleges, etc. The central point of LAN and WAN can be considered and termed as Metropolitan Area Network (MAN). The LAN and WAN are interconnected to form a MAN. The coverage range of MAN is approximately 5 to 50 km. The applications of MAN are military, online reservation systems, banks, etc. (freewimaxinfo.com)
The different network connections are shown in Figure 1. Connections among the devices may be wired or wireless. There are many advantages of computer networks. Some of them are specified below.
Figure 1. Various network connections
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File and thus data sharing,
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Huge data can be stored,
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Resources as well as data can be shared,
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Cost effective, and
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Easy to build.
In the initial stages of introduction of networks, it is expensive to establish a network because more wires are being utilized. But later it became easier and inexpensive and thus reducing the communication complications which virtually reduces the distances between different places in the physical world (freewimaxinfo.com).