Understanding what is involved with setting up an internet account can be a confusing experience. Dial-up, broadband, megabytes, modems and ISP, what do they all mean?
What is an internet service provider?
An internet service provider (ISP) supplies, or arranges to supply, a service that enables users to access the internet. An ISP may own the facilities it uses to deliver the service or it may use the facilities of another provider.
What is a download?
Download (or data downloaded) is any data retrieved from another computer on the internet, for example, text, pictures or sound. For example, viewing a page on the internet is downloading data from another computer.
What is a megabyte?
Megabyte (MB) is the term used to describe a unit of data. 1MB is a data unit of 1,048,576 bytes, sometimes called 1 million bytes. A Gigabyte (GB) is 1,000 Megabytes.
As a guide:
- You can view approximately 20 pages on the internet for each MB of download
- An average four minute MP3 (music file) is approximately 4 MB
- A five-minute movie trailer can be as much as 30 MB
What about modem speeds?
The speed or 'data rate' of a modem is measured by the number of kilobits or megabits of data it can transmit per second. This is expressed as kilobits per second (Kbps). The more Kbps transferred, the faster you will download pages or other material such as music and email from the internet.
The most commonly used dial-up modems have a maximum data rate of 56 Kbps. This is the maximum rate that you can connect to your ISP and the internet when using a dial-up connection. Be aware that this is the maximum rate, not a guaranteed rate; it is not a speed that is normally encountered due to a number of technical reasons.
The most commonly used broadband services have data speeds of 512 Kbps. Faster broadband services are also available, such as a 1,000 Kbps, which is more often called 1 Mbps (1 megabit per second).
You should be aware that 512 Kbps or 1 Mbps is not always a guaranteed service. The actual speed that you experience may be lower because your broadband connection may be shared. The contention ratio is the maximum number of subscribers that may share a 512 Kbps service. For example, the contention ratio may vary from 1:1 (i.e. you are guaranteed that you are the only person using the 512 Kbps service) to 48:1 (i.e. up to 48 users may be sharing the same 512 Kbps service at one time).
Always-On
internet services are categorised as either dial-up or always-on. Dial-up connections require a phone call to allow connection to the internet. The connection is cut off when the phone call is ended.
Always-on services do not require a phone call. They are connected to the internet all day or connect almost instantly. Broadband services are considered always-on, so this should be the first characteristic to be aware of.
Symmetric or Asymmetric Broadband Services
Using the internet usually involves a small request for information (an upload) from the user, followed by a large provision of information (a download) from the internet (e.g. checking for new email). For this reason, most access technologies are designed to provide higher download bandwidth (or speed) than upload bandwidth. These services are described as asymmetric.
Asymmetric services are adequate for most home and SME requirements.
Some more advanced business uses of the internet, like two-way video conferencing, will require the same bandwidth in both directions. In these circumstances, symmetric services such as leased lines or SDSL are required.
So when considering your broadband connection, it is important to distinguish between these two forms and determine which option best suits your needs.
Latency
Latency is the delay that occurs along the transmission path. Latency is a factor with satellite connections because the data must travel over large distances. Due to this, satellite systems are not suitable for businesses that require real-time delivery of information/data.
If you or your organisation require such services, it is important to be aware that satellite will not provide this functionality. However, satellite access is adequate for most home and SME uses of the internet.
Contention
Most broadband access services share a single connection path between many customers - this is referred to as contention. A contention ratio of 40:1 means that up to 40 customers are sharing the same connection. When usage is light, contention does not pose a problem. However, the quality of the connection can deteriorate if many customers use the connection at the same time. For example, if all 40 users are using a 512kbps broadband service at the same time, your access speed is reduced to about 13ksps. In reality, this rarely occurs and is unlikely to significantly impact on your home and internet use, but you should be aware that peak usage times can seem slower because of network congestion. Most of the time, you should be able to connect to 75% - 90% of the top speed available at your location.
When signing up for a broadband service, service providers will quote the contention rate for the service being provided. Contention is an issue with services such as ADSL, satellite and wireless broadband access. Since guaranteed fast broadband access is often more critical to a business, many SMEs consider buying a broadband service with a low contention ratio.
Jitter
Jitter is the slight movement of a transmission signal that can introduce errors and loss of synchronization. Jitter can be thought of as shaky pulses. More jitter will be encountered with longer transmission paths, transmission paths with higher deterioration of a signal and signals at higher data rates. Jitter mainly effects wireless and satellite connections.
Service Level/Availability
Service level or availability is the percentage of time that the connection is guaranteed to be available for use. Businesses selecting a broadband service often look for what is known in industry terms as the six 9s. The service is available 99.9999% of time.