10/13/2015 Nitin J Mutkawoa Add Comment Networking Internet
Have you ever notice that your ISP (Internet Service Provider) advertise you Internet package in a very tricky way? One of the best ways to manipulate you is with the use of the technical term such as Bytes and bits. To be briefer its the term Kilobits per seconds (kbps).
However, if you would be browsing the Internet or downloading some files, you would notice that your browser is indicating the speed at Kilobytes per second (kB/s)
To be more clear, your ISP sells Internet service in terms of kilobits per seconds (kbps) whilst your browser indicates you kilobytes per seconds (kBp/s). The trap is the word b - bits and B - Bytes.
let us say you have applied for a 512 kbps. Firstly, divide your speed by 8 and multiply by 1024 to convert from kilobits per second to bytes per second; i.e 512 x 1024/8 = 65,536 bytes per second Then convert from bytes/s to kilobytes/s
65,535 bytes = 65,535/1000 kB/s = 65.5 kB/s
So, in brief, Internet speed is what is advertised to you and what you pay for! On the other hand, what your browser download speed is What you should get! 512 kbps = 65.5 kB/s 1 Mbps = 122.1 kB/s 2 Mbps = 244.2 kB/s 10 Mbps = 1220.1 kB/s
Now, make as if you are going to download a 700 Megabytes file. What will happen is that your browser will make an estimation of the Downtime. However, you can monitor your downloads with several tools available on the Internet. Let's say you have a 1Mbps Internet connection from your ISP which means that your speed will be 65.5KB/s.
Calculate the Download time as follows
700 x 1024 = 716800 kilobytes (convert from 700 megabytes to kilobytes)
Therefore, if 65.5 kilobytes downloads in 1 sec (i.e 65.5kB = 1 s) then, 716800 kilobytes will download in 716800/65.5 = 5870.6 seconds
5870.597870598 / 60 = 97 minutes
Assume we have still had to subscribe to a 1 Mb. The trick is that when you buy an internet connection. Your ISP does not inform you or commit themselves to what is required! and evade the fact by using the famous word "up to"!! What I am referring is that you pay the internet connection up to "xxx kbps"
This is called CIR - committed information rate. According to Wikipedia, CIR is "Committed information rate or CIR in a Frame Relay network is the average bandwidth for a virtual circuit guaranteed by an ISP to work under normal conditions."
Therefore the CIR is the minimum speed provided by your ISP. Does ISPs provide that CIR? Is this mentioned in the Law? My understanding is that one cannot complain until that CIR is mentioned in the contract!!.
Another issue is something called PEO (Protocol Encapsulation Overhead). When you're buying, say an ADSL link of 2 Mbps, your line is syncing with your ISP at 2 Mbps over ATM or any other backbone technology. (PPOA. PPOE). Now, the catch is that the Point to Point Protocol over ATM (PPOA), needs to be encapsulated over the ATM media. There is an overhead to do so, meaning you are not effectively getting 2 Mbps Internet Protocol connectivity.