Announcements Mobile IPv6 I Dropper is ready II Project due Thursday Dec 1 III Final Exam and Study Guide Internet Protocols CSC ECE 573 Fall 2005 N C State University copyright 2005 Douglas S Reeves 2 Today s Lecture I Mobility II Discovering the Care of Address MOBILITY III Registering the Care of Address IV Normal Data Delivery V Security VI Other Issues copyright 2005 Douglas S Reeves 3 Motivation Why is this Hard Many wireless devices offer IP connectivity Cellphone networks have done this for years what s the difference laptops PDAs cellular phones Non technical reasons Users mobile hosts want to stay connected wherever they may be Technical reasons connections should not be disrupted as mobile hosts move from network to network Cellphone mobility isn t perfect either To route a packet to a mobile host the network first has to find where the host is located means what IP address to use copyright 2005 Douglas S Reeves 5 copyright 2005 Douglas S Reeves 6 1 Tradeoffs Possible Approaches Can you receive incoming connections at new address 1 Just get a new IP address when you attach to a different network Movements transparent to other nodes 2 Get a new IP address announce to other hosts using DNS direct messages Can you maintain currently established connections while moving 3 Get a new IP address but let the rest of the world think you are still at your old IP address Revisions to current protocols required particularly routing protocols and information Security risks copyright 2005 Douglas S Reeves Mobile IPv6 RFC 3775 Foreign Network N1 copyright 2005 Douglas S Reeves 7 8 Some Terminology cont d Home address Correspondent Node all hosts have a home address always reachable there When MN is attached to home network mobile IPv6 not used packets are routed normally to from home address Home Mobile Agent Node care of IP address Care of address home IP address IP address used by mobile host in the visited network changes with each new point of attachment Home Network Note we are ignoring Mobile IPv4 for a reason copyright 2005 Douglas S Reeves A Home agent keeps track of where MN is currently located forwards traffic to from it 9 Mobile IP Mechanisms 10 New Revised Messages Requires several mechanisms New IPv6 Extension Mobility Header main purpose Binding Updates Mobile node discovers the care of address New IPv6 Extension Destination Option Mobile node registers the care of address with the home agent provides home address in IP datagram as well as careof address used for delivery for MN to CN communication Mobile node and home agent tunnel data using the care of address Modified IPv6 Extension Source Routing Optionally mobile node registers the care ofaddress with the correspondent node copyright 2005 Douglas S Reeves copyright 2005 Douglas S Reeves for CN to MN communication 11 copyright 2005 Douglas S Reeves 12 2 New Network Detection How detect that MN is attached to a new network 1 layer 2 notification non standardized or DISCOVERING CARE OF ADDRESSES 2 MN receives new Router Advertisement or does not receive refreshing Advertisement in the time expected 3 MN receives new Router Discovery Reply to a Request it issued In these cases the mobile host should attempt to autoconfigure a new care of address copyright 2005 Douglas S Reeves Home Agents 14 Configuring Care of Addresses Specialized routers Uses the standard configuration mechanisms to get an IPv6 care of address on the foreign network Each maintains home agent list for network routers who have sent Router Advertisements with HA bit set IPv6 auto configuration DHCPv6 Home agent can act as DHCP relay or server for MNs that want to do stateful autoconfiguration When address about to expire MN sends Mobile Prefix Solicitation to HA copyright 2005 Douglas S Reeves copyright 2005 Douglas S Reeves 15 16 Registering Care of Address Once a MN has a care of address its home agent must be notified of the new address REGISTRATION home agent is a router in the home network providing specialized mobility services Binding Update Home Agent Mobile Host Foreign Network Home Network Binding Update ACK copyright 2005 Douglas S Reeves 18 3 Binding Update Message Binding Update Message cont d New IPv6 Extension the Mobility Header Home address specified by contains a set of messages most important Binding Update Message Home Address destination option if present or Source IPv6 Address of packet Request for router to function as home agent home agent has to check for error conditions home address not part of its network host with that address already exists etc Care of address for the MN is specified by the Source IPv6 Address of the datagram containing the Binding Update copyright 2005 Douglas S Reeves 19 Registration must be refreshed periodically otherwise it times out Lifetime number of seconds 4 16 bits long max of 3 days if Lifetime 0 means delete this binding from the cache MN must maintain Binding Update list HAs and CNs who know you are at this care of address copyright 2005 Douglas S Reeves 20 Binding Update Cache Home Agent Discovery Maintained by home agents and correspondent nodes A new ICMPv6 message type is required Home Agent Address Discovery Request and Reply very similar to ICMP Router Request and Reply messages Keeps track of active home address care of address bindings MN anycasts the Request to the home network Contents one home agent replies on behalf of all home agents for that network home address care of address lifetime sequence number copyright 2005 Douglas S Reeves 21 copyright 2005 Douglas S Reeves 22 Returning Home A mobile host is back at its home network when auto configuration returns its home address in this case the mobile host should unregister with the home agent copyright 2005 Douglas S Reeves DELIVERING DATA TO FROM MOBILE NODES 23 4 Mobile IPv6 Tunneling Mobile IPv6 Tunneling cont d The destination MN decapsulates the packet and delivers it to application A packet sent to MN H is routed to H s home network Data from MN to CN goes through a reverse tunnel intercepted by the home agent The home agent from MN to HA tunneled tunnels the packet to the care of address from HA to CN not tunneled i e encapsulate IP packet for H inside an IP packet sent to care of address copyright 2005 Douglas S Reeves copyright 2005 Douglas S Reeves 25 Example CN to MN Tunneled Example MN to CN Tunneled Internet Internet X X S CNaddr D HOaddr Mobile Host COaddr S HOaddr D CNaddr Mobile Node Home Agent S HAaddr D COaddr