A method of operating a network (120) is provided in a communications system for communications among a plurality of routers in the network. The network receives verifiable information identifying at least one compromised router (D). The method includes a step to excise the compromised router (D) from the network. The method also includes steps to verify that messages transmitted between routers (A, B, C, D, E and F) are from non-compromised routers (A, B, C, E and F), and to reinstate the compromised router (D) when it becomes non-compromised.