Definition - What does Line Speed mean?
When using internet services, line speed refers to the maximum speed a line can support. Fifty Mbps is an example of line speed. Line speed depends on several factors such as line quality, distance of the cabinet or exchange and whether the ADSL micro-filters are installed correctly. It is not always possible for a line to function at its highest potential speed.
Techopedia explains Line Speed
Line speed can depend on the plan purchased from an internet service provider (ISP). Even then, it may not be possible to get the highest available speed all the time because of several factors. For example, while a highway may allow a maximum speed of 65 mph, it may not always be possible to travel at that speed, especially if it has been snowing hard or there is a traffic jam – it works the same way in the case of line speed.
When the highest speed is affected, the resultant speed is known as the throughput speed. The throughput speed is the actual download speed of an internet connection as opposed to that stated in the internet plan. Throughput speed varies depending on the server load or whether the service is being used at peak hours, for example. The best time to achieve the line speed may be during non-peak hours, especially when the number of users of the internet service may be low.