In some examples, aggregation-based speed testing may include ascertaining, by a test speed analyzer, a test speed that corresponds to a maximum specified data transfer rate for a data transmission link. A test range generator may determine a maximum specified port speed of a test port of a device connected to the data transmission link. The test range generator may determine whether the maximum specified port speed is less than the test speed, and if so, divide the test speed into a plurality of test ranges. A total value of the test ranges may be equal to the test speed. A test performer may perform tests corresponding to the test ranges, and obtain intermediate test results. A test result generator may generate, based on aggregation of the intermediate test results, an aggregated test result that represents an actual speed associated with the data transmission link.