Transcript Slide 1
Mobile IP IP Internet 212.10.123.23 180.4.34.12 IP address is used by router to direct data packet to it’s destination. IP address works well if user is static. If User is moving while active session, How to handle it? Cellular Network 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. Mobile IP Addressing Possible Solution Keep Up – address and update routing tables. Not feasible to update all routers every time whenever host moves to a new network Get a New IP This requires that configuration files are changed. Ongoing transmission will be interrupted. Two addresses - Home address - Care 0f address Mobile IP Mobile IP Home Address: Mobile host original home address. 13.10.121.11/16 182.12.11.78/24 Internet 182.12.11.0/24 13.10.0.0/16 Care of address: Mobile host original home address. Mobile IP Mobile IP Mobile IP adds mobility support to the Internet network layer protocol IP. The Internet started at a time when no-one had a concept of mobile computers. The Internet of today lacks mechanisms for the support of users traveling through the world. IP is the common base for thousands of applications and runs over dozens of different networks; this is the reason for supporting mobility at the IP layer. Addressing Mobile IP has two addressing The home address is permanent; The care-of address changes as the mobile host moves from one network to another. Mobile IP Terminology Mobile Node (MN) system (node) that can change the point of connection to the network without changing its IP address Home Agent (HA) system in the home network of the MN, typically a router registers the location of the MN, tunnels IP datagrams to the COA Foreign Agent (FA) system in the current foreign network of the MN, typically a router forwards the tunneled datagrams to the MN, typically also the default router of the MN Care-of Address (COA) address of the current tunnel end-point for the MN (at FA or MN) actual location of the MN from an IP point of view Correspondent Node (CN) communication partner Addressing How these addresses are converted into each other? Who will handle these addressing to provide communication services without interruption? Mobile IP Agent Agent provide transparent change in address. Home Agent. Foreign Agent. Mobile IP Home Agent & Foreign Agent Mobile IP Communication • Example network HA MN router home network Internet (physical home network for the MN) FA foreign network router (current physical network for the MN) CN end-system router 12 Communication • Data transfer to the mobile system HA 2 MN home network Internet receiver 3 FA 1 CN sender foreign network 1. Sender sends to the IP address of MN, HA intercepts packet 2. HA tunnels packet to COA, here FA, by encapsulation 13 3. FA forwards the packet to the MN Communication • Data transfer from the mobile system HA 1 home network MN sender Internet FA foreign network 1. Sender sends to the IP address of the receiver as usual, FA works as default router CN receiver 14 Mobile host to Remote host communication To communicate with remote host, mobile host requires three phases. 1. Agent Solicitation 2. Registration 3. Data Transfer Mobile IP Mobile host to Remote host communication 16 Mobile IP Mobile host to Remote host communication Agent Advertisement HA and FA periodically send advertisement messages into their physical subnets MN listens to these messages and detects, if it is in the home or a foreign network (standard case for home network) MN reads a COA from the FA advertisement messages Registration (always limited lifetime!) MN signals COA to the HA via the FA, HA acknowledges via FA to MN these actions have to be secured by authentication Advertisement HA advertises the IP address of the MN (as for fixed systems), i.e. standard routing information Routers adjust their entries, these are stable for a longer time (HA responsible for a MN over a longer period of time) Packets to the MN are sent to the HA, independent of changes in COA/FA Remote host to mobile host communication 1 2 3 Mobile IP Inefficiency in Mobile IP-Double Crossing 1 2 Communication involving mobile IP can be inefficient. The inefficiency can be severe or moderate. The severe case is called double crossing or 2X . The moderate case is called triangle routing or dog-leg routing. Mobile IP Inefficiency in Mobile IP-Triangle routing 1 2 3 Sender sends all packets via HA to MN higher latency and network load Solutions – optimization HA informs a sender about the location of MN . Sender learns the current location of MN direct tunneling to this location big security problems! Mobile IP Questions Q. Explain when mobile IP is needed Q. Why and where is encapsulation needed for mobile IP? Q. Explain packet flow if two mobile nodes communicate and both are in foreign networks. What additional routes do packets take if reverse tunnelling is required? Q. What is meant by tunnelling? Explain how tunnelling works for mobile IP using IP-in-IP. Discuss the advantages and disadvantages of this method. Q. Name the inefficiencies of mobile IP regarding data forwarding from a correspondent node to a mobile node. What are optimizations and what additional problems do they cause? Q. What are general problems of mobile IP regarding security? Q. What is the basic purpose of DHCP? Name the entities of DHCP. Q. How can DHCP be used for mobility and support of mobile IP?