With the increased mobility of end devices, the requirements for the speed with which mobile end devices, mobile nodes (MN), perform the handover in WLANs also increase. In IP networks, the mobility of the end devices is handled by the Mobile-IP (MIP) specified by the Internet Engineering Task
Force (IETF). Since mobile devices are increasingly used for multimedia services and in real time, the time delay caused by latency during handover or roaming plays a crucial role. Just think of Internet telephony
with VoIP.For these applications, the Internet Engineering Task Force (IETF) has specified Fast Handovers for Mobile IPv6 (FMIP) for WANs and UMTS
andpublished it in RFC
FMIP describes a protocol for reducing delay times and preventing packet loss in mobile IP, based on IPv4
and IPv6. In WLAN handover and WLAN roaming, it is important to know in which radio cell the mobile terminal is located and which subnet the radio cell belongs to. Is it the same subnet or a different one? In the first case, it is a handover at the data link layer, which is performed using the Inter Access Point Protocol (IAPP). In the case of different IP subnets, on the other hand, roaming is implemented in the network layer, which, however, involves a prior handover at the data link layer. Mobile IP (MIP) is used when switching to another access point (AP).