Ad authentication route in a fast router discovery (FRD).

A method for authenticating a mobile node (110) A first Advertisement received from an Access Point (128), the method comprising the steps of: receiving at the Mobile Node from the Access Point first router advertisement comprising a first Network Prefix, a nonce index and a first Hashed Nonce Value; configuring at the Mobile Node a first IP address using a first Network Prefix, and concurrently authenticating the first Advertisement by: receiving at the Mobile Node from an Access Router (150) a second router advertisement, comprising second router advertisement a nonce value for the Nonce Index and a second network prefix; hashing at the Mobile Node the Nonce value for calculating a second Hashed Nonce Value; and compare the Mobile Node Hashed Nonce the first value and the second Hashed Nonce Value; and maintain at the Mobile Node the first IP address if the first Hashed Nonce Value is equal to the second Hashed Nonce Value.