Bài giảng TCP/IP - Chapter 27: Mobile IP

Chapter 27MobileIPCONTENTS ADDRESSING AGENTS THREE PHASES AGENT DISCOVERY REGISTRATION DATA TRANSFER INEFFICIENCY IN MOBILE IPADDRESSING27.1The IP addresses are designed to work with stationary hosts because part of the address defines the network to which the host is attached.Figure 27-1Host address and care-of addressMobile IP has two addresses for a mobile host: one home address and one care-of address. The home address is permanent; the care-of address changes as the mobile host moves from one network to another.AGENTS27.2Figure 27-2Home agent and foreign agentWhen the mobile host and the foreign agent are the same, the care-of address is called a co-located care-of address.THREE PHASES27.3Figure 27-3Remote host and mobile host communicationAGENT DISCOVERY27.4Figure 27-4Agent advertisementMobile IP does not use a new packet type for agent advertisement; it uses the router advertisement packet of ICMP, and appends an agent advertisement message. Mobile IP does not use a new packet type for agent solicitation;it uses the router solicitation packet of ICMP.REGISTRATION27.5Figure 27-5Registration request and replyFigure 27-6Registration request formatFigure 27-7Registration reply formatA registration request or reply is sent by UDP using the well-known port 434.DATA TRANSFER27.6Figure 27-8Data transferThe movement of the mobile host is transparent to the rest of the Internet.INEFFICIENCYIN MOBILE IP27.7Figure 27-9Double crossingFigure 27-10Triangle routing