Patent ID: 8918522

Claim:
A method of re-establishing a session between first and second hosts attached to respective first and second access routers, the session previously having been conducted via a previous access router to which said first host was attached, and where a security association comprising a shared secret has been established between the first and second hosts, the method comprising: the first access router receiving a connection request from said first host, said connection request containing an IP address claimed by said second host, a new care-of-address for the first host, and a session identifier; the first access router, upon receipt of said connection request, obtaining a verified Internet Protocol (IP) address for said second access router and sending an on link presence request to the second access router, the on link presence request containing at least an interface identifier (IID) part of the second host's claimed IP address, said care-of-address, and said session identifier, wherein said second access router is configured to: confirm that said second host is attached to the second access router using the IID, send to the second host said care-of-address and said session identifier, and send to the said first access router a presence status message reporting the presence status; and the first access router receiving the presence status message, wherein said first and second access routers share a pair of group keys that are used by the routers to generate anonymized Interface Identifiers for use in both source and destination Internet Protocol version 6 (IPv6) addresses of the first and second hosts, and wherein a first group key SGKn is generated by said first access router upon receipt of the connection request from the first host and is included in the on link presence request sent to the second access router, and a second group key DGKn is generated by the second access router upon confirmation that the second host is attached to the second access router at its claimed IP address and is included in the presence status report sent to the first access router.