Embodiments described herein provided methods and apparatus for controlling switching a power supply of a first network node between an electrical power grid and an alternative power supply in which the first network node is configured to transmit data to a second network node over a data transmission link. The method includes receiving first information indicative of a predicted decrease in a transmission rate of data transmitted by the first network node over the data transmission link. Responsive to receiving the first information, a first request is transmitted to the first network node to switch the power supply of the first network node from the electrical power grid to the alternative power supply.