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Routing Issues in Mobile IP Sudarshan Vasudevan Chun Zhang PART 1 Unicast Routing using Mobile IP Terminology Care-of-Address Tunneling DHCP (Dynamic Host Configuration Protocol) HA - Home Agent FA - Foreign Agent MH - Mobile Host CH - Correspondent Host 1. Overview Mobile IP Provide Host Migration Transparency small modifications to IP routing is sufficient Involves 3 basic functions Advertisement Registration Tunneling Protocol When MH is in its home network Normal IP Routing When MH is away from it home network HA keeps track of MH’s care-of-address either FA’s IP address or one obtained using DHCP Care-of-Address represents the MH’s current location When the MH migrates into another foreign network, MH notifies its new care-of-address to the HA Example HA CH MH FA MH Ha n d-O ff / Ro am ing Wired backbone network Tunneling & Triangular Routing Normal IP datagram Destined for MH 141.223.84.1 HA CH Tunneling Datagram Tu nn el Data Entry for HA Data Entry for HA Foreign MH entry 141.223.84.60 = 0F:0F:0F:0F:0F:0F ARP cache Entry of FA for MH 141.223.84.60 = 00:00:00:00:00:00 Remote MH entry IP address Care-of-Address 141.223.84.60 141.223.120.1 141.223.120.1 FA 141.223.84.60 Data Entry for MH MH ARP cache Entry of MH 141.223.120.1 = FF:FF:FF:FF:FF:FF 141.223.84.60 = 0F:0F:0F:0F:0F:0F Tunneling & Triangular Routing 141.223.84.1 HA Encapsulation nn e l Triangular Route Tu CH IP header IP payload 141.223.120.1 FA text IP payload IP-within-IP Encapsulation Decapsulation 141.223.84.60 MH new IP header IP header Route Optimization Triangular path is not optimal route Route Optimization Supply binding update to CHs authentication and replay protection for binding updates registration key between MH and FA for smooth handoff Route Optimization Cache the current care-of-address of MH Binding Update HA CH FA1 MH After Binding Update Smooth Hand-Off Cache the current care-of-address of MH (4) Binding Update HA CH Control Packet Flow (3) Binding warning FA1 (2) Binding update to FA1 (2) Register with HA FA2 (1) Register with FA Hand-Off MH MH Conclusion Triangular Routing can be eliminated sending binding updates to CHs Smooth handoffs very valuable counteract unwanted effects of dropped packets special tunnels can further reduce this effect Main difficulty establishment of security associations between FA and MH Future Work Mobility Security Association Management authentication of all messages that affect routing currently manual establishment of MSAs difficult to manage, no scalability efficient Key Distribution Protocols needed Certification of Foreign Agents prevent malicious nodes pretending as FAs Security issues introduced by Tunneling References Perkins, Charles E., ed. “Ipv4 Mobility Support” RFC 2002. October 1996b. Perkins, Charles E. “Minimal Encapsulation within IP”. RFC 2004.October 1996c. Perkins, Charles E. “IP Encapsulation within IP”. RFC 2003. October 1996a. Perkins, Charles E and Johnson, David B. “Mobility Support in IPv6.” In ACM Mobicomm9 6. November 1996. Johnson, David B. “Scalable and Robust Internetwork Routing for Mobile Hosts” In Proceedi ngs of the 14th International Conference on Distributed Computing Systems. June 1994. Hanks Stan, Tony Li, Dino Farinacci, and Paul Traina,Generic Routing Encapsulation over IP v4 networks. RFC 1702. October 1994b. Deering, Stephen E., ed., “ICMP Router Discovery Messages.” RFC 1256. September 1991. Hellman, M.E., W.Diffie, and R.C. Merkle. “Cryptographic Apparatus and Method.” US Pate nt 4,200,770. April 1980. Rivest, Ronald L. “The MD5 Message-Digest Algorithm”. RFC 1321. April 1992. Maughan, Douglass, Mark Schetler, Mark Schneider, and Jeff Turner. Internet Security Asso ciation and Key Management Protocol (ISAKMP). (Internet-draft) draft-ietf-ipsec-isakmp08. txt, .ps. July 1997. PART 2 Multicast Routing using Mobile IP Multicast algorithms classification Unicast dependent vs. Unicast independent Source-Based vs. Shared Multicast Tree [Directly impact on Mobile IP] Sparse mode vs. Dense mode Protocols: DVMRP, MOSPF, CBT, PIM(Dense/Sparse) Unicast dependent vs. Unicast independent Which one is better ? Multicast Unicast • Use property of specific unicast routing algorithm Multicast Unicast • Use general unicast function • Extra Multicast related state • Deploy limitation • Better interoperability • DVMRP(RIP) MOSPF(OSPF) • Protocol Independent Multicast Source-Based vs. Shared Multicast Tree Source-Based Tree (DVMRP,MOSPF,PIM_Dense) Source2 (113.117.238.2) Source1(128.119.240.5) A B C Receiver 1 F D E Receiver 2 ? How to maintain LEAST UNICAST-COST PATH TREE • Multicast Open Shortest Path First • Distance Vector Multicast Routing Protocol Source-Based vs. Shared Multicast Tree Forwarding Packet with Source-Based Tree Reverse Path Forwarding Algorithm Transmit the packet on all of its outgoing links only if the packet arrived on the link that is on its own shortest path back to the source Source A C Receiver 1 B D Receiver 2 E Receiver 3 Source-Based vs. Shared Multicast Tree Shared Tree (Core Base Tree, PIM_Sparse) Source 1 Source 2 A B D (Shared Root) C E Receiver 1 Receiver 2 F Sparse mode vs. Dense mode Sparse mode Pay Per View Few receiver Join explicitly Dense mode Radio Broadcast Few non-receiver Join by default Broadcast prune,graft Shared/Source based tree Source based tree CBT, PIM_Sparse DVMRP, PIM_Dense Sparse Mode PIM Example Source Link Data Control A B C Receiver 1 D RP E Receiver 2 Sparse Mode PIM Example Receiver 1 Joins Group G C Creates (*, G) State, Sends (*, G) Join to the RP Source A B D RP Join C Receiver 1 E Receiver 2 Sparse Mode PIM Example RP Creates (*, G) State Source A B C Receiver 1 D RP E Receiver 2 Sparse Mode PIM Example Source Sends Data A Sends Registers to the RP Source Register A B C Receiver 1 D RP E Receiver 2 Sparse Mode PIM Example RP de-encapsulates Registers Forwards Data Down the Shared Tree Sends Joins Towards the Source Source Join A Join B C Receiver 1 D RP E Receiver 2 Sparse Mode PIM Example RP Sends Register-Stop Once Data Arrives Natively Source Register-Stop A B C Receiver 1 D RP E Receiver 2 Sparse Mode PIM Example C Sends (S, G) Joins to Join the Shortest Path (SPT) Tree Source A B D RP (S, G) Join C Receiver 1 E Receiver 2 Sparse Mode PIM Example When C Receives Data Natively, It Sends Prunes Up the RP tree for the Source. RP Deletes (S, G) OIF and Sends Prune Towards the Source Source (S, G) Prune A B D RP (S, G) RP Bit Prune C Receiver 1 E Receiver 2 Sparse Mode PIM Example New Receiver 2 Joins E Creates State and Sends (*, G) Join Source A B D RP (*, G) Join C Receiver 1 E Receiver 2 Sparse Mode PIM Example C Adds Link Towards E to the OIF List of Both (*, G) and (S, G) Data from Source Arrives at E Source A B C Receiver 1 D RP E Receiver 2 Sparse Mode PIM Example New Source Starts Sending D Sends Registers, RP Sends Joins RP Forwards Data to Receivers through Shared Tree Source Register A B C Receiver 1 D RP E Receiver 2 Source 2 Dense Mode PIM Example Source A Link Data Control B G C D F H E Receiver 1 I Receiver 2 Dense Mode PIM Example Source Initial Flood of Data and Creation of State A B G C D F H E Receiver 1 I Receiver 2 Dense Mode PIM Example Source Prune to Non-RPF Neighbor A B G Prune C D F H E Receiver 1 I Receiver 2 Dense Mode PIM Example Source C and D Assert to Determine Forwarder for the LAN, C Wins A B G C D F Asserts H E Receiver 1 I Receiver 2 Dense Mode PIM Example Source I Gets Pruned E’s Prune is Ignored G’s Prune is Overridden A Prune B G C D F H Prune E Receiver 1 Join Override I Receiver 2 Dense Mode PIM Example Source New Receiver, I Sends Graft A B G C D F H Graft E I Receiver 1 Receiver 2 Receiver 3 Dense Mode PIM Example Source A B G C D F H E I Receiver 1 Receiver 2 Receiver 3 Multicast + Mobile IP Mobile Host as Sender Using Home Address as packet source address Using Care-of Address as packet source address Mobile Host as Receiver Home Subscription Join multicast group using Home Address Remote Subscription Join multicast group using Care-of Address Home Address as packet source address Option 1: Packet directly sent out from foreign network For Source-Based Tree (routing related to packet source address) Packet might not be delivered For Central Based Tree (routing uncorrelated to packet source address) Packet will be delivered correctly Option 2: Packet tunneled to Home Agent, then sent out Packet will be delivered correctly Care-of Address as packet source address Packet directly sent out from foreign network Packet will be delivered correctly Problem: How the misdelivered response reach the roaming sender ? Home Subscription Packet first received at Home Agent, then forward to the mobile host. Problem: Tunnel Convergence problem Source Home Agent (A) Home Agent (B) Foreign Agent Mobile Host (A) Mobile Host (B) Home Subscription Packet first received at Home Agent, then forward to the mobile host. Problem: Tunnel Convergence problem Source Home Agent (A) Designated Multicast Service Provider Mobile Host (A) Home Agent (B) Foreign Agent Mobile Host (B) Remote Subscription It works fine since multicast packet is delivered based on multicast group address Foreign network router should support multicast Conclusion Mobile Host as Sender Using Home Address as packet source address Core Based Tree/ Tunneled packet sent out from Home Agent Using Care-of Address as packet source address Hardly to use Mobile Host as Receiver Home Subscription Tunnel convergence problem Remote Subscription Foreign network support multicast References Mobile Multicast(MoM) Protocol: Multicast Support for Mobile Hosts. Tim G. Ha rrison, Carey L. Williason, Wayne L. Mackrell, Richard B. Bunt. U. of Saskatchew an, Saskatoon, Canadan.Proceedings of the third annual ACM/IEEE international c onference on Mobile computing and networking. September 26 - 30, 1997, Budape st Hungary RelM: Reliable Multicast for Mobile Networks.Journal of Computer Communicati ons, 1997.Kevin Brown, Suresh Singh Supporting IP Multicast for Mobile Hosts, for review.Yu Wang, Weidong Chen.Sou thern Methodist University Flexible Network Support for Mobile Hosts. X. Zhao, C. Castelluccia, M. Baker. P roc. MOBICOM '98, Dallas, Texas, 1998, pp. 145--156 IP Multicast Extensions for Mobile Internetworking. In Proceedings of IEEE Infoc om'96, March 1996 IP Multicasting for wireless mobile hosts. George Xylomenos and George C. Poly zos. Proceedings of the IEEE MILCOM, 10 1996