he handover in this case is performed via R3 reference point with tunneling over R4 to transfer undelivered packets. Figure 2-6 illustrates three different mobility scenarios supported in WiMAX networks. When the mobile station moves from positions 1 to 2, or 1 to 3, an ASN-anchored mobility through R8 or R6 reference points, respectively, is implied, whereas moving from position 1 to 4 involves a CSN- anchored mobility scheme though R3 reference point. 2.6.1 ASN-anchored Mobility ASN-anchored mobility management is defined as mobility scenario not involving a care-of address update (i.e., an MIP re-registration). The procedures described for ASN-anchored mobility manage- ment also apply for mobility in networks that are not based on mobile IP. The functional requirements for ASN-anchored mobility management include support of different mobility classes, minimization of packet loss and handover latency while maintaining packet ordering, compliance with the security architecture defined in the IEEE 802.16-2009 specification and IETF EAP protocols, support of private addresses allocated by the H-NSP or V-NSP, support of Macro-Diversity Handover (MDHO) and Fast Base Station Switching (FBSS) handover mechanisms, support of MS in active, idle, and sleep modes (see Chapter 6 for details), minimization of the number of roundtrip signaling between BS and CHAPTER 2 WiMAX Network Architecture (MIP HA) Inter-ASN R3 Mobility ASN-GW ASN-GW (MIP FA) (MIP FA) Intra-ASN R6 Mobility Intra ASN R8 Mobility Direction of Motion FIGURE 2-6 Mobility scenarios supported in the WiMAX network architecture intra-ASN mobility anchor point to execute handover, independence of handover control primitives, and data path enforcement control primitives such that it allows separation of handover control and data path enforcement control, and consideration for QoS. The ASN-anchored mobility management is defined by data path function (DPF), which manages the data path setup and includes procedures for data packet transmission between two functiona