It just doesn't get much simpler than the physical bus topology when it comes to connecting nodes on a Local Area Network (LAN). The most common implementation of a linear bus topology is IEEE 802.3 Ethernet. All devices in a bus topology are connected to a single cable called the bus, backbone, or ether. The transmission medium has a physical beginning and an end. All connections must be terminated with a resistor to keep data transmissions from being mistaken as network traffic. The terminating resistor must match the impedance of the cable.
One advantage of bus topology is that small networks are fairly easy to set up and does not require specialized networking equipment. It is also fairly inexpensive to set up, since it requires the least amount of cable and equipment. Adding or removing nodes is fairly easy, but moving nodes without affecting neighboring nodes can be difficult.
Troubleshooting media problems on a bus networks can be very tedious, since a break in the backbone will bring down the entire LAN. For this reason, bus topology is not considered one of the more robust network topologies, compared with star or mesh. A loose or missing terminating resistor can also bring down a LAN.
In this topology, all nodes are connected to a central device, usually a hub or a switch. Each connected device has a dedicated, point-to-point connection between the device and the hub. The star network topology is by far the most widely implemented topology in use today.
Star topology networks require more cabling than bus, but the tradeoff comes in the form of a more solid network topology. A break in the network media will only affect a single node, since every node has a dedicated connection to the central device; a hub or switch. This also makes the central device a Single Point of Failure (SPOF). Redundant or failover switches are often used to eliminate the SPOF in a star LAN.
References: Harwood, Mike, Tittel, Ed (Ed.) (2003). Network+ Exam Cram (Exam N10-002). Indianapolis, IN: Que Certification. Kozierok, Charles M. (2004). The TCP/IP Guide. Retrieved August 14, 2005 from http://www.tcpipguide.com/index.htm. McQuerry, Steve (Ed.) (2004). CCNA Self-Study: Introduction to Cisco Networking Technologies (INTRO). Indianapolis, IN: Cisco Press. Tomsho, Greg, Tittel, Ed, Johnson, Greg (2004). Guide to Networking Essentials [University of Phoenix Custom Edition e-text]. Thomson Learning, Inc. Retrieved Aug 14, 2005 from University of Phoenix, Resource, NTC/360 – Network and Telecommunications Concepts Web site: https://ecampus.phoenix.edu/secure/resource/resource.asp.