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Building Secure Wireless Networks with 802.11 phần 2

Sao Topology Trong một tôpô sao, tất cả các thiết bị được kết nối với một trung tâm trung tâm (xem hình minh hoạ 1.9). Các nút giao tiếp trên mạng bằng cách truyền dữ liệu thông qua trung tâm. Bởi vì giao thức dễ dàng để phát triển, mạng lưới tư nhân sử dụng nó. | Star Topology In a star topology all devices are connected to a central hub see Figure 1.9 . Nodes communicate across the network by passing data through the hub. Because the protocol is easy to develop many private networks use it. The mesh topology connects each node with every other node creating an isolated data path between each node. Mac II Figure 1.9 Star topology. Star topology has a very high performance but works in a limited geographical area and is very costly as the wires from each computer must run all the way to the central hub. Most wireless networks use a variation of the star topology without wires of course . Choosing the Right Topology Which topology you deploy should be based upon connectivity requirements budget and the available hardware. The bus topology is the simplest to implement and is the most widely used network topology. The ring topology is the most expensive to implement. Bus topology is extremely common in enterprise LANs however their backbones are often designed using the ring topology to give higher performance. Ring topology attains better performance over bus topology because the physical medium that data travels on is not shared among all computers on the network only adjacent computers share the given medium whereas in bus topology all computers connected to the network share the same physical medium resulting in collision and medium congestion network becomes too busy and hence lower performance. Wireless LANs use the star topology because it provides a better management of the network bandwidth. Network Hardware and Software In this section we talk about the networking components software and the protocols that are 18 required for each computer in a network. For a network to function all the computers must have compatible network software and hardware and they must be connected to one another via a physical link a cable for example. Networking Components A computer in a network must have a network interface card NIC .