Communications system, mobile node apparatus, and method of performing a handover

摘要

A communications system comprises a first network node ( 102 ) and a second network node ( 110 ). A mobile node ( 108 ) attached to the first network node ( 102 ) hands over from communicating with the first network node ( 102 ) at a link layer ( 208 ) of a protocol stack to communicating with the second network node ( 110 ) by performing a link layer handover procedure. Thereafter, the link layer ( 208 ) of the mobile node ( 108 ) interrogates incoming packets to identify a router advertisement packet ( 300 ) broadcast by the second network node ( 110 ). Upon receipt of the packet ( 300 ), the link layer ( 208 ) modifies the packet ( 300 ) to include trigger information ( 518 ) in an IPv6 Destination Options Extension Header ( 508 ). The packet ( 300 ) is then passed up the protocol stack to a network layer ( 210 ) thereof, where the modified packet ( 300 ) is recognised as containing the trigger information ( 518 ) and a network layer handover procedure is initiated in response to receipt of the modified packet ( 300 ).