In Part II we discussed a little bit in more detail what a communication network constitutes of. In brief the network consists of the end systems, the communication link and the switching devices all of which play a significant role in network traffic management.
I also promised that in this part we shall discuss congestion management, which promise I intend to keep.
As usual I will first share some of the feedback from readers. One reader wanted to know whether Corner Stone Africa (the company that I work for) is an IT company.
To this I say NO! In all honest I should have ignored this feedback. On second thought, however, I got the impression that the reader possibly suffers from a read-laziness scourge that is quite prevalent in our midst.
Surely all one needs to do is logon to www.cornerstone-africa.com and there glaringly lays the answer. For the benefit of this reader’s like, Cornerstone Africa specializes in Workforce Skills Development.
We, however, use ICT tools quite extensively either to solution our managerial challenges or market and sell our products.
A good example is our highly interactive online ‘Job Forum’ that brings together job seekers and job providers.
Another reader wanted to know whether I have gone back to school, probably referring to my new found writing skills. To this one I say YES! You will agree with me that everyday is a learning experience to which the environment is a capable teacher.
May we all heed our lessons; amen! I personally have taken my lessons. I took to writing partly to constantly stimulate my brain so as to defy aging and partly to deny the devil possible habitation.
Back to my promise, let us discuss what may cause network congestion first before we think of managing it. Plainly speaking, network congestion is caused by bottlenecks within the data path as it is transmitted from one end user to another.
The bottleneck at each device in the network contributes to the totality of congestion in the network. Our next challenge is to understand what causes the bottlenecks and that is one of the big secret that I will try to unveil!
By design, network assets have limited capacities that may be exceeded by user demands. When the demand exceeds the capacity, data is queued in the different assets of the network.
When data is queued for a predetermined duration it will overflow leading to congestion and/or data loss. The totality of delays in each network asset will contribute to the congestion of the network.
It is all about the usual principles of demand and supply and fair distribution based on first-come- first- serve. It is as simple as that.
If you arrive at the edge of the network before me you will most likely be routed in before me unless the ICT wizards have played some tricks, which they usually do.
Yes, this is no joke especially for big networks whenever they want to impress certain clients or for some common good reasons. We shall come to this later.
Back to the bottlenecks, I will use some examples to explain my case. Consider the communication link.
As we saw data is transferred from one device to another using physical transport media such as cable or radio spectrum (the in-thing is optic fibre).
The nature and characteristics of each media will determine the limit of transmission speed. Different media have different bandwidth.
A small bandwidth transport medium in a high speed network may be a source of congestion. Also if a network consists of different transport media, data may experience delays when moving from one medium to another due to their different characteristics.
Remember our highway analogy? Imagine how your speed sharply drops when you turn off from the highway to a non-macadamized road! Another quick example is your computer.
If the computer has a low memory and a low processor speed, it may cause processing delays that will contribute to throughput speed.
Low speed computers may be a source of network congestion especially when they a
re used to process big amounts of data.
Maybe by now some truths about your woes in the cybercafé have started unfolding. I will unveil some more secrets next Friday; stay tuned to this page.
The writer is the Managing Director of Cornerstone Africa Ltd