Networking Topologies

How Networks are Commonly Structured


star




About Topologies



Networking topologies can be categorised as follows:

Alternatively, they can be listed like so:

  1. Bus
  2. Ring
  3. Star
  4. Tree (Star-Bus)
  5. Mesh

"Topology refers to the layout of connected devices. Network topology is defined as the interconnection of the various elements (links, nodes, etc.) of a computer network." (More info on http://www.sudarshansoftech.com/chnt3.htm) There are literally thousands of ways in which large computer networks can be set up, but here are some diagrams of a few of the common, smaller-scale ones:

Topologies diagrams

Figure 27: Common network topologies (Picture from ibid)

The study of topology utilises graph theory, which is taught in higher mathematics but rarely in standard IT courses.


Dispensing with the graph theory, then, here follows a synopsis of each of the common network layouts:

Point-to-Point

[Diagram not shown] "The simplest topology with a dedicated link between two endpoints [...] The value of a permanent point-to-point network is unimpeded communications between the two endpoints. The value of an on-demand point-to-point connection is proportional to the number of potential pairs of subscribers and has been expressed as Metcalfe's Law." (Wikipedia)

Bus

[See diagram above] Not to be confused with a computer's system bus, a bus topology is utilised as follows: "Each node is connected to a single cable, by the help of interface connectors. This central cable is the backbone of the network and is known as the bus (thus the name). A signal from the source travels in both directions to all machines connected on the bus cable until it finds the intended recipient. If the machine address does not match the intended address for the data, the machine ignores the data." (Wikipedia)

Star

[See diagram above] In a star topology, "Each network host is connected to a central hub with a point-to-point connection. So it can be said that every computer is indirectly connected to every other node with the help of the hub." (Wikipedia) The obvious drawback to this network layout is that if the hub goes down, the whole network stops functioning.

Ring

[See diagram above] Wikipedia: "A ring topology is a bus topology in a closed loop. Data travels around the ring in one direction. When one node sends data to another, the data passes through each intermediate node on the ring until it reaches its destination. The intermediate nodes repeat (re transmit) the data to keep the signal strong. Every node is a peer; there is no hierarchical relationship of clients and servers. If one node is unable to re transmit data, it severs communication between the nodes before and after it in the bus."

Advantages:

When the load on the network increases, its performance is better than bus topology.
There is no need of network server to control the connectivity between workstations.

Disadvantages:

Aggregate network bandwidth is bottlenecked by the weakest link between two nodes.

Mesh

[See diagram above] Mesh topologies come in two forms: fully connected and partially connected.

"Some WANs, most notably the Internet, employ mesh routing. A mesh network in which every device connects to every other is called a full mesh." (http://www.sudarshansoftech.com/chnt3.htm)

A fully connected mesh topology is impractical for larger networks, as each terminal must be connected to all the others. However, in large (partially connected) mesh networks, each node of the mesh still plays its part in relaying data throughout the network.



IP Addresses



Basically, an IP address is "a unique string of numbers separated by full stops that identifies each computer using the Internet Protocol to communicate over a network." (Google)

See here for information on address classes, which vary depending on the scale of the network.

Credit to Microsoft for providing this GIF image of the TCP/IP structure on their excellent information page about TCP/IP here.


TCP/IP diagram

Figure 28: TCP/IP Protocol Architecture

It looks complicated, and personally I have found networking to be the most difficult aspect of IT study at TAFE, except perhaps dynamic web design (which we did in Certificate IV, see web site here).

Therefore I won't try to describe it, merely quoting this sentence from the same MSDN page in summary: "The Internet Protocol (IP) is a routable protocol responsible for IP addressing, routing, and the fragmentation and reassembly of packets." Packets contain data, and the TCP/IP protocol is a sophisticated way of transmitting that data over networks.




© 2016-2020 Leo Coroneos
Certificate IV in Information Technology
South Regional TAFE, Albany WA Australia