Mobile communication has received a lot of attention in the last decade. The interest in mobile communication on the Internet means that the IP protocol, originally designed for stationary devices, must be enhanced to allow the use of mobile computers, computers that move from one network to another. | Chapter 27 Mobile IP CONTENTS ADDRESSING AGENTS THREE PHASES AGENT DISCOVERY REGISTRATION DATA TRANSFER INEFFICIENCY IN MOBILE IP ADDRESSING The IP addresses are designed to work with stationary hosts because part of the address defines the network to which the host is attached. Figure 27-1 Host address and care-of address Mobile 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. AGENTS Figure 27-2 Home agent and foreign agent When the mobile host and the foreign agent are the same, the care-of address is called a co-located care-of address. THREE PHASES Figure 27-3 Remote host and mobile host communication AGENT DISCOVERY Figure 27-4 Agent advertisement Mobile 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. REGISTRATION Figure 27-5 Registration request and reply Figure 27-6 Registration request format Figure 27-7 Registration reply format A registration request or reply is sent by UDP using the well-known port 434. DATA TRANSFER Figure 27-8 Data transfer The movement of the mobile host is transparent to the rest of the Internet. INEFFICIENCY IN MOBILE IP Figure 27-9 Double crossing Figure 27-10 Triangle routing | Chapter 27 Mobile IP CONTENTS ADDRESSING AGENTS THREE PHASES AGENT DISCOVERY REGISTRATION DATA TRANSFER INEFFICIENCY IN MOBILE IP ADDRESSING The IP addresses are designed to work with stationary hosts because part of the address defines the network to which the host is attached. Figure 27-1 Host address and care-of address Mobile 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. AGENTS Figure 27-2 Home agent and foreign agent When the mobile host and the foreign agent are the same, the care-of address is called a co-located care-of address. THREE PHASES Figure 27-3 Remote host and mobile host communication AGENT DISCOVERY Figure 27-4 Agent advertisement Mobile 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. REGISTRATION Figure 27-5 Registration request and reply Figure 27-6 Registration request format Figure 27-7 Registration reply format A registration request or reply is sent by UDP using the well-known port 434. DATA TRANSFER Figure 27-8 Data transfer The movement of the mobile host is transparent to the rest of the Internet. INEFFICIENCY IN MOBILE IP Figure 27-9 Double crossing Figure 27-10 Triangle routing
