host that changes network while retaining the home address (HoA) provided by its home network (Figure 8.1). Mobile Mobile proxy-CoAl proxy-CoA2 Mobile Figure 8.1. PMIPv6 architecture Wi-Fi Integration to the 4G Mobile Network, First Edition. André Perez. C ISTE Ltd 2018. Published by ISTE Ltd and John Wiley & Sons, Inc. 148 Wi-Fi Integration to the 4G Mobile Network The mobile access gateway (MAG) is integrated into gateway router of the mobile node and provides mobility management for the mobile node connected to its local network (Figure 8.1). The local mobility anchor (LMA) is built into the router that acts as the home agent (HA) of the mobile node and represents the anchor point for the mobile node (Figure 8.1). In the case of auto-configuration, the LMA function provides the mobile node with an IPv6 home network prefix (HNP), from which the mobile node builds its HoA. If not, the MAG function hosts a DHCPv6 server that assigns the HoA to the mobile, built from the IPv6 HNP. The LMA function registers in the BCE (Binding Cache Entry) table the identity MN-ID of the mobile and the proxy care-of address (CoA) of the MAG of the mobile node. The tunnel built between the MAG and LMA functions is characterized by the proxy-CoA on the MAG side and the LMA address (LMAA) on the LMA side. The local mobility domain (LMD) is a set consisting of an LMA function and several MAG functions attached to the LMA function (Figure 8.1). 8.1.1. Mobility extension The mobility extension of the IPv6 header, described in section 9.1.1.1, has defined two types for the MIPv6 mechanism, namely Binding Update and Binding Acknowledgment. These two types are modified for their use adapted to the PMIPv6 mechanism. The PBU (Proxy Binding Update) extension is the request transmitted by the MAG function to the LMA function to populate the BCE table with the MN-ID identity and the proxy-CoA. The PBA (Proxy Binding Acknowledgment) extension is the response of the LMA function containing the HNP assigned to the mobile. S2a/S2b Tunnel Establishm