A topology defines the arrangement of nodes (computers, printers, hubs, switches, etc.) and cables that form a network. Topologies can be defined as Physical a description of the layout of the network cabling and Logical a description of the signal path through the network devices. The underlying network technology will employ one of the following basic types of topologies:
Bus
Ring
Star
The basic topologies can be combined to form hybrid topologies in the form of a Tree or Mesh to solved problems of scalability and redundancy.

The Bus topology is characterized by a single backbone cable supporting directly connected workstations and other network enabled devices. This topology was generally used in the 1980's and is associated with 10 Mbps (megabits per second) Ethernet using 10Base2 (ThinNet), 10Base5 (ThickNet), and 10BaseT UTP (unshielded twisted pair). A major problem with the bus topology is that a single connected device, or backbone cable failure will bring the entire network down.

Pros
* Easy to implement
* Low cost

Cons
* Backbone cable breaks affects everyone.
* Cable length and number of device limits.
* Hard to isolate failures.
* Performance decreases as the number of workstations increase.

When each network device has exactly two directly connected neighbors it's on a network configured as a Ring topology. Like a Bus topology a Ring topology is subject to a total failure if the ring cable breaks, or a node malfunctions. The Fiber Distributed Data Interface (FDDI) specification eliminated that liability through the use of a dual ring configuration. If one ring breaks, the ring loops back using the other ring to self-heal itself to restore connectivity. Don't be confused by protocols like 802.5 Token Ring. 802.5 employs a star topology at the physical layer and a token passing logical ring topology at the link level of the protocol.

Pros
* Better performance under heavy load then a Star topology.
* Token passing provides orderly data transmission.

Cons
* Ethernet has high performance under low loads.
* More expensive than Ethernet to implement.
* Faulty node or cable can cause total network outage.

A Star topology is composed of a central network switch (not a hub a hub is a passive device that creates a Bus topology) to interconnect nodes. The switch regulates

• 1
• 2
• next page >>

---

Add your voice

Know something about Basics of network topologies?
We want to hear your view. Write now!