How your ADSL usage is measured

Whether you’re on a capped or uncapped broadband service, Internet service providers measure your data usage.

With this data usage information, ISPs are able to enforce caps and fair use policies – guaranteeing they have enough capacity to meet the demand on their networks.

A fair use policy typically lets an ISP shape or throttle a subscriber’s bandwidth, usually with the goal of ensuring a good experience for everyone on the network.

High-usage uncapped ADSL subscribers are generally the first to feel the effects of heavy shaping and throttling – with ISPs looking at bandwidth usage and usage patterns to determine whose connections to slow down.

This then raises the question: How do ISPs measure data consumption on their networks?

How ADSL ISPs measure data usage

Afrihost, Cybersmart, MWEB, Telkom, and Webafrica said they use RADIUS logs to measure users’ data traffic.

RADIUS (Remote Authentication Dial-In User Service) is a protocol which offers authentication and accounting management on network services.

MWEB provided the following breakdown of how it measures ADSL usage:

  1. RADIUS accounting records from Telkom are stored in a MySQL database cluster as they are delivered.
  2. A custom Linux-based system, using Perl scripts and Oracle and MySQL databases, collect the RADIUS accounting records and stores them for long-term access.
  3. Various custom-developed systems access the data via a business logic layer to display the usage information to support staff and customers.

In addition to the above, MWEB said it has a business intelligence platform that stores usage patterns for individual customers.

Other ISPs use similar techniques. Cybersmart said it primarily uses RADIUS logs for usage data, but can get detailed per-user data via its traffic shaping systems.

Telkom Internet was the one exception, saying it relies on the usage data collected by its network appliances.

“The measured usage is allocated based on the time of day the customer is browsing, to enable SoftCap as well as the night surfer feature of the Telkom Internet product,” the ISP said.

Units of measurement

ISPs were also asked which units they use to measure data consumption.

Afrihost, Cybersmart, MWEB, and Telkom said they use the binary or International Electrotechnical Commission standard.

This means that prefixes such as kilo, mega, and giga use multiples of 1,024 (210) for each tier, as opposed to the SI standard which uses 1,000 (103).

In other words, a gigabyte is taken to mean 1,024 megabytes, while a megabyte is 1,024 kilobytes.

Technical note: The IEC standard provides for a different naming convention, with 210 being kibi, 220 mebi, and 230 gibi.

How ADSL data usage is measured

The infographic below summarises how ISPs measure data usage.

How your ADSL usage is measured
How your ADSL usage is measured

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How your ADSL usage is measured