The seven layers identified by ISO in the OSI reference model from bottom to top are: 1. Physical Layer 2. Data Link Layer 3. Network Layer 4. Transport Layer 5. Session Layer 6. Presentation Layer 7. Application Layer. The physical layer is concerned with transmission of data through communication channels, these communication channels do not themselves form part of the [...]
This article throws light upon the top six methods of data transmission. The methods are: 1. Twisted Pair 2. Shielded Twisted Pair 3. Baseband Coaxial Cable 4. Broadband Coaxial Cable 5. Fibre Optics 6. IEEE Standards. Method # 1. Twisted Pair: As must be obvious from the example, transferring data by copying it onto magnetic tape or floppy disk or [...]
SMDS or Switched Multimegabit Data Service is another service being offered by telephone companies in many countries. This service, which had become popular in the USA in the 90s, was developed by Bellcore in 1980. Figure 6.6 indicates how normal leased line connections can be established between some LANs. Telephones: Other Issues: Other telephone services include items, such as Synchronous [...]
After reading this article you will learn about the two popular routing algorithms: 1. Dijkstra's Algorithm 2. Bellman-Ford Algorithm. 1. Dijkstra's Algorithm: Almost all packet-switching networks base their routing on some form of packet-switching network. Most least-cost algorithms in use in packet-switching networks and in the internet are variations of either Dijkstra's Algorithm or the Bellman-Ford Algorithm. In Dijkstra's Algorithm, [...]
After reading this article you will learn about the concept of fibre distributed data interface (FDDI). FDDI is a high-performance Token Ring LAN running at 100 Mbps over distances up to 200 km handling stations of the order of 1000. It can be used like copper wire in IEEE 802 LANs but is sometimes used as a backbone to connect [...]
This article throws light upon the top four issues caused by media access protocols. The issues are: 1. ALOHA 2. Slotted ALOHA 3. Carrier Sense Multiple Access 4. CSMA with Collision Detection. Issue # 1. ALOHA: ALOHA is the product of the thought process of Norman Abramson who, in the 1970s, along with his colleagues in the University of Hawaii, [...]
The three likely services to be provided by the data link layer are: 1. Unacknowledged connectionless service 2. Acknowledged connectionless service and 3. Acknowledged connection-oriented service. 1. Unacknowledged Connectionless Service: When the source machine sends independent frames to the destination machine without the destination machine acknowledging the receipt and no connection having been established in advance or released afterwards, we [...]
After reading this article you will learn about the two important types of classifications that are generally based on the transmission technology and on the scale and size of the geographical are covered. The classification based on transmission technology are: 1. Broadcast Networks 2. Point-to Point Networks. 1. Broadcast Networks: Broadcast networks have a single communications channel that is connected [...]
This article throws light upon the top two types of Intranet. The types are: 1. The Internal Web 2. The External Web (Extranet). Type # 1. The Internal Web: The Web consists of the external web, the extranet known as the Internet and the internal web, known as the Intranet. When you look at the sheer volume of information stored [...]
This article throws light upon the three main computer networks. The networks are: 1. LAN 2. MAN 3. WAN. Computer Network # 1. Local Area Networks (LAN): These networks are generally referred to as LANs. In fact, the acronyms LAN for Local Area Network and WAN for Wide Area Network have become so popular that many computer users would be [...]