The invention relates to a routing optimization method of communication between a mobile node in a PMIPv6 (Proxy Mobile IPV6 (
Internet Protocol Version 6)) domain and a communication node in a MIPv6 (Mobile IPv6). The routing optimization method is realized by expanding functions of an MAG (Mobile Access Gateway) so that the MAG can support a BU / BA (Binding Update / Binding
Acknowledgement) message, a HoTi / HoT message and a CoTI / CoT message in the MIPv6. The MAG has a local routing function; when receiving
data messages from an MN (Mobile Node), the MAG can look up a
routing table; if a corresponding table entry is looked up, the table entry forwards the
data messages; and if the corresponding table entry is not looked up, a routing optimization process is started. The routing optimization process comprises the steps: the MAG sends an LRI (Local Routing initialization) message to an LMA (Local Mobility Anchor) and receives an LRA (Local Routing
Acknowledgement) message replied by the LMA; the MAG starts an RRP (Return Routability Procedure); and the MAG sends the BU message to an CN (Communication node) and receives a BA message replied by the CN. After the optimization process is finished, the MAG can establish a new
routing table entry so that the MAG can be directly communicated with the CN.