Internet MobilityReferencesSlide 3OutlineMotivationChallengesSome SolutionsBasic TerminologySplit TCPSlide 10TCP SplicingSlide 12Mobility using Foreign AgentSlide 14Encapsulation: IP in IPEncapsulation IssuesMobility without Foreign AgentImplementation in MosquitoNetHome Agent FunctionalityMovement of MH away from home networkMovement of MH to home networkAdvantages of using Foreign AgentAdvantages of NOT using Foreign AgentTriangular RoutingProblems with Routing TechniquesSource Address Filtering ProblemSlide 27Routing Optimizations - ISlide 29Slide 30Routing Optimizations - IISlide 32Slide 33Slide 34Routing Optimizations - IIISlide 36Slide 37Slide 38Routing Optimizations - IVSlide 40Slide 41Slide 42Slide 43Making CH intelligentGains using optimizationsPractical implementation of optimizationsSecurity IssuesMobile Policy Table PerformanceMobile Policy Table and FlexibilityWhy support multiple pkt delivery methodsWhy support multiple network intefacesConclusionIssues to think aboutNitin Bahadur Distributed Systems Spring 2000 1Internet MobilityPresented by: Nitin BahadurNitin Bahadur Distributed Systems Spring 2000 2References•Mary Baker, Xinhua Zhao, Stuart Cheshire, Jonathan Stone, Supporting mobility in Mosquitonet, Proceedings of USENIX, Technical Conference, 1996.•Stuart Cheshire and Mary Baker, Internet Mobility 4x4, SIGCOMM ‘96.•Kevin Lai, Mema R., Diane Tang, Xinhua Zhao, Mary Baker, Experiences with a Mobile Testbed, Proceedings of WWCA ‘98.Nitin Bahadur Distributed Systems Spring 2000 3References•C. Perkins, IP Mobility Support for IPv4, Internet Draft, draft-ietf-mobileip-rfc2002-bis-01.txt, Jan 2000.•C. Perkins, Route optimization in Mobile IP, Internet Draft, deaft-ietf-mobileip-opim-09.txt, Feb 2000.•David Maltz, Pravin Bhagwat, MSOCKS: An Architecture for transport layer mobility, IEEE INFOCOM ‘98.Nitin Bahadur Distributed Systems Spring 2000 4Outline•Motivation and Challenges•Some proposed solutions•IP Mobility •Routing Optimizations •Security Issues•Recent Extensions•ConclusionsNitin Bahadur Distributed Systems Spring 2000 5Motivation•Ubiquitous connectivity, continuous connectivity.•Ability to maintain current conversations/connections during movement.•Move from one kind of network to another.•Move to networks that do NOT provide support for mobility.Nitin Bahadur Distributed Systems Spring 2000 6Challenges•Movement causes change in IP address•Problems with TCP connections•Maintaining transparency•Efficient routing to new location of mobile host•Security issuesNitin Bahadur Distributed Systems Spring 2000 7Some Solutions•Use Host specific routes - possible with IPv6.•Link Layer solutions–Limited to a single medium–A new solution for every medium–Compatibility issues with other mediums•Use extended DNS to register COA with DNS–Information propagation time–Global change in DNSNitin Bahadur Distributed Systems Spring 2000 8Basic Terminology•Mobile Host (MH)•Correspondent Host (CH)•Home Agent (HA)•Foreign Agent (FA)•Care of Address (COA)InternetCHHAFAMHNitin Bahadur Distributed Systems Spring 2000 9Split TCP•Two TCP connections, CH<=>HA<=>MH•Transport Layer mechanismInternetTCP - ITCP - IIHA CHNitin Bahadur Distributed Systems Spring 2000 10Split TCP• Two TCP connections instead of one• Changed end points• HA acks. packets to CH even before MH has received them.• Home agent is responsible for final packet delivery• Multiple traversal through the TCP protocol stack• HA needs to maintain a TCP connection for every TCP connection of all its mobile hostsNitin Bahadur Distributed Systems Spring 2000 11TCP Splicing•Two TCP connections, CH<=>HA<=>MH•Transport Layer mechanism•Acks are sent on TCP-I to CH only when MH sends them on TCP-IIInternetHATCP - ITCP - IICHNitin Bahadur Distributed Systems Spring 2000 12TCP Splicing+ The scheme works like 1 TCP connection+ Location transparency is maintained- Multiple traversal through the TCP protocol stack- HA still needs to maintain a TCP connection for every TCP connection of all its mobile hostsNitin Bahadur Distributed Systems Spring 2000 13Mobility using Foreign Agent•MH obtains COA from FA•FA discovery using Agent Advertisement or Agent Solicitation messages•MH host registers COA with HA through FA • HA intercepts packets for MH • HA encapsulates and sends packets to FA• FA decapsulates packets and sends it to MH• Everything done at IP level……no TCPSame mechanism in the reverse directionThis is called Bidire ctional tunnelingNitin Bahadur Distributed Systems Spring 2000 14Mobility using Foreign AgentFAInternetHACHNitin Bahadur Distributed Systems Spring 2000 15Encapsulation: IP in IP•Encapsulation maintains consistency in Source and Destination address fields.•Allows MH to receive packets as it moves from network to network.Source = CHDestn = MHSource = HADestn = MHSource = CHDestn = COASource = CHDestn = MHHA FADATADATADATANitin Bahadur Distributed Systems Spring 2000 16Encapsulation Issues•IP encapsulation and automatic decapsulation is dangerous•How can one verify if the inner packet has a source address if claims to be !•Encapsulation can cause packet fragmentation–TCP breaks data in chunks of 1460 bytes and gives it to IP–Encapsulation will automatically lead to packet fragmentation in such cases. So extra overhead.Nitin Bahadur Distributed Systems Spring 2000 17Mobility without Foreign Agent•MH obtains a COA using DHCP•MH registers COA with HA directly•MH performs encapsulation and decapsulationInternetCHHANitin Bahadur Distributed Systems Spring 2000 18Implementation in MosquitoNetAltered the route lookup function ip_rt_routeMobile Policy Table helps in combination with ip_rt_route is used for making routing decisionsNitin Bahadur Distributed Systems Spring 2000 19Home Agent Functionality•Maintaining information about MH’s current location•Acting as an ARP proxy for MH–ARP…. to get link-layer address for an IP address–Proxy ARP…..done to answer a new ARP request on behalf on MH–Gratuitous ARP….done to update ARP information of MH in all nodes•Forwarding packets to CH and MHNitin Bahadur Distributed Systems Spring 2000 20Movement of MH away from home network•Detection by MH–received a different agent advertisement message–stopped receiving agent advertisement messages• Disable ARP• Register with FA or HA• HA performs