This disclosure describes methods and systems to for a method for a first computing node to receive frequency information of a system clock. The first computing node receives the frequency information of the system clock from a second computing node at a physical layer of a connection between the first computing node and the second computing node. The first computing node also receives a message from the second computing node at above the physical layer of the connection between the first computing node and the second computing node. The message includes an attestation of the frequency information from which the first computing node may verify that the second computing node is a trusted source of the frequency information.