Article Preview
Top1. Introduction
Proxy Mobile IPv6 (PMIPv6) (Gundavelli & Leung, 2008) is a network-based mobile management protocol for localized domains which enables IP mobility for a host without requiring its participation. Comparing with the host-based protocol (such as Mobile IPv6), the host in PMIPv6 do not need to have the client function of mobility management, the mobility entities in the network are responsible for tracking the movement of the host and initiating the required mobility signaling on its behalf.
Since PMIPv6 was proposed in 2008, the Internet Engineering Task Force (IETF) has done a lot of meaningful work about it. Now the primary RFCs (Request For Comments) about PMIPv6 are as follows:
- •
RFC5844 (Wakikawa & Gundavelli, 2010): This document specifies extensions to the PMIPv6 protocol for adding IPv4 protocol support, including enable IPv4 home address mobility support to the mobile node, and allow the mobility entities in the PMPv6 domain to exchange signaling messages over an IPv4 transport network;
- •
RFC6572 (Xia & Sarikaya, 2012): This document defines a RADIUS-based profile and corresponding attributes to be used on the AAA (Authentication, Authorization and Accounting) interface between the Mobile Access Gateway (MAG) and the AAA RADIUS server. This interface is used to carry the per-MN (Mobile Node) policy profile from the remote policy store to the MAG. Furthermore, this document also defines a RADIUS-based interface between the Local Mobility Anchor (LMA) and the AAA RADIUS server for authorization of the received PMIPv6 signaling messages;
- •
RFC6705 (Krishnan & Koodli, 2012): This document proposes initiation, utilization, and termination mechanisms for localized routing between MAGs within a PMIPv6 domain. It defines two new signaling messages, Localized Routing Initiation (LRI) and Local Routing Acknowledgment (LRA), that are used to realize this mechanism.
Thus, PMIPv6 develops rapidly and has made lots of achievements. Many researchers propose new handover process to reduce handover latency.
RFC5949 (Yokota & Chowdhury, 2010) propose fast handover for PMIPv6. Before MN switches to new network, previous MAG (PMAG) sends the Handover Initiate (HI) message to the new MAG (NMAG) and NMAG sends the Handover Acknowledge (HAck) message back to PMAG. After that, a bidirectional tunnel is established between previous MAG and new MAG, and packets sent to mobile node are forwarded from the PMAG to the NMAG over this tunnel. After decapsulation, those packets are buffered at the NMAG until MN attaches to NMAG. If the connection between the new access network and new MAG has already been established, those packets are forwarded towards the new access network.
Kang & Kum (2008) proposed a seamless handover that uses the Neighbor Discovery message of IPv6 to reduce the handover latency and packet buffering at the MAG to avoid the on-the-fly packet loss during a handover. In addition, it uses an additional packet buffering at LMA to solve the packet ordering problem.
Zhang & Tian (2016) presented a triggering mechanism for Fast PMIPv6. It makes use of the information from the link layer to establish a bi-directional tunnel in advance for handover, and improves the handover performance.