Wel come
As mentioned, the network was hierarchical. There was the top-level backbone to which regional networks connected. Local networks then connected to the regional networks via a relatively short link. The backbone network and the regional networks were managed by different authorities and provided bandwidth and transport services for local networks. Bandwidth was resold. The ISP business model was developed by the early network providers and service providers. Entrepreneurs could set up facilities in their local area and purchase bandwidth, routing, and transport services from higher-level NSPs. The local ISP would then resell those services to end users. Many ISPs were started by one person who had extra bandwidth to sell.
Computer
A typical ISP installs dial-up facilities (modems, modem banks, concentrators, access and authentication servers, and so on) and then metered and billed users for service. Network Architecture A network's architecture generally defines its overall structure, including its topology, physical media, and channel access method. The following is a brief summary of the more popular architectures used in networking to day. Ethernet Developed by Xerox, Ethernet is the most popular network architecture today. It has many advantages, including ease of installation and lower costs. Ethernet is generally less expensive than most other architectures. Another reason that it is so popular is that it can support the use of many different media types (cable). Ethernet uses a channel access protocol called CSMA/CD (Carrier Sense Multiple Access with Collision detection). Simply put, this protocol oversees the transmission of data across the wire. If a machine is transmitting, it is not possible for another machine to transmit at the same time. It must wait till the medium is free. If it does transmit, the data sets will collide, causing a garbled signal. So the role of Carrier Sense is to be able to detect if the wire is available.
