Mobile IP Add it into TCP/IP implementation

Wireless communication techniques Wireless technique DistanceTransfer rate Frequency Bluetooth (WPAN) 10 m3M bps2.4 GHz Wi-Fi (WLAN) m54 Mbps WiMAX (WMAN) 50 km for fixed station 5-15 km for mobile one 30 Mbps- 75 Mbps? 2-66 GHz 2-11 GHz? 3G (W-CDMA, TD-SCDMA,...) 384 Kbps- 14 Mbps OFDM-MIMO

1. Introduction Discuss IP address and routing for mobile host (MH). MH moves from one network to another ---> its IP address and routing change MH moves within wireless LAN ---> its IP address and routing don’t change Changing an address is time-consuming, requires rebooting computer, and breaks all existing TCP connections

2. Mobile IP and some concepts IETF devised mobile IP, a solution to the mobility problem. Transparency. Applications always use MH’s home address. All open TCP connections survive a change in network Interoperability with IPv4 MH can interoperate with stationary hosts that run conventional IPv4 software

home net. ： the network on which MH registers foreign net. ： home address ： IP address obtained on home net. It is permanent and fixed. Applications use it care-of address ： IP address obtained at foreign net. It is temporary (variable). IP layer uses it. home agent ： a router on home net. It agree to intercept and tunnel datagrams to MH. foreign agent ： Concepts:

3. Overview of mobile IP operation 1) MH finds that itself moves to a foreign network 2) MH obtains a care-of address from FA 3) MH(FA) informs HA of its care-of address 4) HA intercepts datagrams sent to the MH’ home address, and tunnel each datagram to the care-of address 5) when MH returns home, it contact HA to deregister The issues to be solved are 1), 2), 4)

4. Foreign agent discovery --- for 1) MH uses ICMP router discovery mechanism to find that itself moves to a foreign network. Recall:Recall routers periodically send ICMP router advertisement messages to all nodes on the net. a host can send an ICMP router solicitation to prompt for an advertisement:

1) Foreign agent discovery MH has a default router. If MH receives an ICMP router advertisement message from other router, it know that itself moves to a foreign network. To confirm it, MH can send an ICMP router solicitation message to ?HA and waits for a reply FA

2) Agent registration MH send registrations request to FA, which then contacts HA on its behalf. Registration message includes: { home address, care-of address, HA, …} FA

5. Obtains a care-of address --- for 2)2) Router advertisement message piggybacks additional information known as a mobility agent extension which includes care-of addresses : In practice, there are two types of care-of addresses foreign agent care of addressIPv4 co-located care-of addressIPv6 Care-of address

Foreign agent care of address is one of FA’ IP addresses so that MH doesn’t consume IP address. Co-located care-of address is a new IP address allocated to MH by DHCP. It requires MH to handle all forwarding itself.

6. Datagram transmission and reception--- for 4) IP A IP B Send ?

The mobile creates a datagram that has destination computer’s address in the destination field and the mobile’s home address in the source field. IP B shortest path 1) MH sends datagram

IP B IP A IP HA IP FA IP B IP A Receive

Datagram will travel to the mobile’s home network. HA intercepts the datagram and uses IP-in-IP encapsulation to tunnel the datagram to the care-of address FA decapsulates the datagram and transmit the datagram to the mobile. FAHA 2) MH receives datagram