US Patent 9641525 External authentication support over an untrusted network

There are provided measures for supporting an authentication to an external packet data network over an untrusted access network, said measures exemplarily comprising authenticating a user equipment to a communication network providing connectivity for the user equipment across an unsecured access network in response to a first authentication request, wherein the authentication request is an authentication request of a key information exchange mechanism and includes authentication data, receiving a second authentication request for authenticating the user equipment towards a packet data network external to the communications network. The measures may further comprise creating a binding update message including the authentication data and identity information of the user received from the user equipment.