Today we learnt about network categorization. Networks are usually classified using three properties: Topology, Protocol and Architecture.
Topology specifies the geometric arrangement of the network. Network topology is the study of the arrangement of the elements (links, nodes) of a network, especially the physical (real) and logical (virtual) interconnections between nodes.
Physical Topology: The physical layout of devices on a network or the way that the devices on a network are arranged and how they communicate with each other.
Logical Topology: The mapping of the flow between the nodes in the network determines the logical topology of the network.
Main Types of Physical Topology
Linear Bus
A linear bus topology consists of a main run cable with a terminator at each end. All nodes (file server, workstations, and peripherals) are connected to the linear cable.
Advantages
- Easy to connect a computer to a linear bus
- Require less cable length than a star topology.
Disadvantages
- Entire network bus shuts down if there is a break in the main cable.
- Terminators are required at both ends of the backbone cable.
- Difficult to identify the problem if the entire network shuts down.
- Not meant to be used as a stand-along solution in a large building.
Star
A star network structures consists of individual computer connected to a central point on the network. Start network are the most common type of a network.
In a star network, each computer is connected to a central network connected, called a hub. All information that transfers from one computer to another on the network passed through the hub.
Advantages
- Easy to install and wire.
- No disruptions to the network when connecting or removing devices.
- Easy to detect faults and to remove parts.
Disadvantages
- Requires more cable length than a linear topology.
- When the hub fails, information can no longer transfer from one computer to another.
- More expensive than linear bus topologies because of the cost of the hubs.
Tree
A tree (hybrid) topology combines characteristics of linear bus and star topologies. It consists of groups of star-configured workstations connected to a linear bus backbone cable.
Tree topology allows for the expansion of an existing network, and enable schools to configure a network to meet their needs.
Advantages
- Point-to-point wiring for individual segments.
Disadvantages
- Overall length of each segment is limited by the type of cabling used.
- Of the backbone line breaks, the entire segment goes down.
- More difficult to configure and wire than other topologies.
Network Protocol
- Network Protocol specifies a common set of rules and signlas the computers on the network use to communicate. Most networks use Ethernet, but some networks may use IBM Token Ting protocol.
- Other network protocol like LocalTalk protocol allows for linear bus, star, or tree topologies using twiested pair cable. A primary disadvantage of LocalTalk is speed. Its speed of transmission is only 230Kbps.
- Fiber Distributed Data Interface (FDDI) is a network protocol that is used primarily to interconnect two or more local area networks, often over large distances. FDDI uses a dual ting physical topology.
- Asynchronous Transfer Mode (ATM) is a network protocol that transmits data at a speed of 155Mbsp and higher. ATM works by transmitting all data in small packets of a fixed size; whereas, other protocols transfer variable length packets. ATM supports a variety of media such as video, CD-quality audio and imaging. As ATM technology becomes more cost-effective, it will provide another solution for constructing faster local area networks.
Summary of Protocol
Ethernet-Linear Bus, Star, Tree
LocalTalk-Star
FDDI-Dual Ring
ATM-Linear Bus, Star, Tree
Network Architecture: Peer-to-peer, Client/server.
Little Reflection of the day♥
Most server design to be upgraded and most improved throughout their lifespan. Hence, before installing a server, it is important to determine the future needs of the server. The network administrator should plan ahead so that server does not have to be replaced with newer models when inexpensive upgrades could be performed.
