A method reduces signaling overhead of a mobile node that maintains at
least one active Next Steps in Signaling session. The mobile node has a
MOBIKE connection to a virtual private network gateway, and changes its
link to the Internet. At least the IP address of the VPN gateway and/or
an address space corresponding to the subnetwork of the VPN gateway
is/are inserted into the message routing information object contained in
the NSIS message. A value is defined for a security parameter index. The
SPI value is inserted into the MRI object. The S flag is set in the MRI
object. An address space that refers to the IP address of the mobile node
is inserted into the MRI object.