Mobile networking should not be confused with portable networking • Portable networking requires connection to same ISP • Portable Networking Technology • Cellular systems • Cellular Digital Packet Data (CDPD) • 3G • Bluetooth • Low cost, short range radio links between mobile devices • Wireless Ethernet (802.11)
Mobile networking • IP assumes end hosts are in fixed physical locations • IP addresses enable IP routing algorithms to get packets to the correct network • Each IP address has network part and host part • This keeps host specific information out of routers • DHCP is used to get packets to end hosts in networks • This still assumes a fixed end host • What happens if we move a host between networks?
Without Mobile IP, devices must tear down and set up connections as they move from location (network) to location (network) • They change network so they must change IP address • Mobile users don’t want to know that they are moving between networks IP address A Internet IP address B
Mobile IP was developed as a means for transparently dealing with problems of mobile users • Enables hosts to stay connected to the Internet regardless of their location • Enables hosts to be tracked without needing to change their IP address • Requires no changes to software of non-mobile hosts/routers • Requires addition of some infrastructure • Has no geographical limitations • Requires no modifications to IP addresses or IP address format • Supports security • Could be even more important than physically connected routing
Mobile IP and its Variants • Mobile IPv4 (MIPv4) • MIPv4 • Low-Latency Handover for MIPv4 (FMIPv4) • Regional Registration for MIPv4 (HMIPv4) • Mobile IPv6 (MIPv6) • MIPv6 • Fast Handover for MIPv6 (FMIPv6) • Hierarchical MIPv6 (HMIPv6)
IETF RFCs • MIP • MIPv4: RFC 3344 (2002) • MIPv6: RFC 3775 (2004) • FMIP (Fast Handover for MIP • FMIPv6: RFC 4068 (2005) • Fast Handovers for Mobile IPv6 • FMIPv4: RFC 4881 (2007) • Low-Latency Handoffs in Mobile IPv4 • HMIP (Hierarchical MIP) • HMIPv6: RFC 4140 (2005) • Hierarchical Mobile IPv6 • HMIPv4: RFC 4857 (2007) • Mobile IPv4 Regional Registration
MIPv4: Overview • MIPv4 Nodes • MN (Mobile Node): Host • CN (Correspondent Node): Host • HA (Home Agent): Router • FA (Foreign Agent): Router • MIPv4 Address • HoA (Home Address): MN • CoA (Care-of-Address): FA
Home Address (HoA) and Care-of Address (CoA) 220.127.116.11 Care-of address 18.104.22.168 Home address • The home address is permanent • The care-of address changes as the mobile host moves from one network to another.
Home Agent (HA) • A router with additional functionality • Located on home network of MN • Does mobility binding of MN’s IP with its CoA • Forwards packets to appropriate network when MN is away • Does this through encapsulation • Foreign Agent (FA) • Another router with enhanced functionality • If MN is away from HA the it uses an FA to send/receive data to/from HA • Advertises itself periodically • Forward’s MN’s registration request • Decapsulates messages for delivery to MN
Protocols Operation • Agent Discovery (MN FA (CoA)) • HA’s and FA’s broadcast their presence on each network to which they are attached • It is possible for a mobile node to solicit agent advertisement to avoid waiting for an agent to advertise. • Beacon messages via ICMP Router Discovery Protocol (IRDP) • MN’s listen for advertisement and then initiate registration • Registration to HA (via FA) (MN FA HA) • When MN is away, it registers its CoA with its HA • Typically through the FA with strongest signal • Registration control messages are sent via UDP to destination port 434 • Data Transfer Through Tunneling • CN => HA (HoA) => FA (CoA) => MN • IP-in-IP Tunneling, ..
MIPv4: Control & Data Flows (Maintain “Visitor list”) (Maintain Mobility Binding Table) Mobile IP does not use a new packet type for agent solicitation; it uses the router solicitation packet of ICMP.
Tables maintained on routers • Mobility Binding Table • Maintained on HA of MN • Maps MN’s home address with its current CoA • Visitor List • Maintained on FA serving an MN • Maps MN’s home address to its MAC address and HA address
Agent advertisement • MIP does not use a new packet type for agent advertisement; • it uses the router advertisement packet of ICMP, and • appends an agent advertisement message.
The Tunneling • HA encapsulates all packets addressed to MN and forwards them to FA • IP tunneling • FA decapsulates all packets addressed to MN and forwards them via hardware address (learned as part of registration process) • NOTE that the MN can perform FA functions if it acquires an IP address eg. via DHCP • Bidirectional communications require tunneling in each direction
The Mobile Node sends packets using its home IP address • effectively maintaining the appearance that it is always on its home network. • Data packets addressed to the Mobile Node are routed to its home network, where the Home Agent now intercepts and tunnels them to the care-of address toward the Mobile Node. • Tunneling has two primary functions: encapsulation of the data packet to reach the tunnel endpoint, and decapsulation when the packet is delivered at that endpoint. • The default tunnel mode is IP Encapsulation within IP Encapsulation • Typically, the Mobile Node sends packets to the Foreign Agent, which routes them to their final destination, the Correspondent Node • The above data path is topologically incorrect because it does not reflect the true IP network source for the data—rather, it reflects the home network of the Mobile Node. • Because the packets show the home network as their source inside a foreign network, an access control list on routers in the network called ingress filtering drops the packets instead of forwarding them.
A feature called reverse tunneling solves the problem by having the Foreign Agent tunnel packets back to the Home Agent when it receives them from the Mobile Node
Mobile node (MN) Mobile IP in Action CN is successfully communicating with MN via HA Mobility Binding table Correspondent node (CN) HA Looks binding table Home Address = A Home Agent (HA) 1.MNsendsRegistration request with its new CoA 2.Mobile binding created for MN with new CoA 3.MNsendsRegistration response, after validating request and updating binding table Remote Agent (RA) 4.Packets sent toMNfromCNare tunneled toRA using binding table CoA = B Mobile Node moves to remote network
Key Objective of MIP The movement of the mobile host is transparent to the rest of the Internet.
Mobile IPv6 (MIPv6) • MIPv6 = MIPv4 + IPv6 • Major Differences from MIPv4 • FA in MN • No FA for MIPv6 • CoA: IP address of MN • By DHCPv6 or IPv6 Stateless Auto-Configuration • Route Optimization • To solve the “Triangular Routing” Problem • Provided by default • MN CN
MIPv6: Binding Update • Binding Update to HA • Using IPSEC: MN and HA have a security association • AH (Authentication Header) • ESP (Encapsulating Security Payload) • Binding Update to CN • Return Routability (RR) procedure • For Security • Binding Update (BU) procedure • Route Optimization
MIPv6: Changes to IPv6 • New IPv6 Protocol (Header) • Mobility Header: a new IPv6 extension header • To carry MIPv6 Binding Update messages • How is in the MIPv4 ? • New Option in Destination Option Header • Home Address Option • New Type in Routing Header • Type 2 Routing Header • New ICMP Messages • ICMP HA Address Discovery Request/Reply • ICMP Mobile Prefix Solicitation/ Advertisement
MIPv6: Mobility Header • A New Extension Header of IPv6 • Messages for Return Routability • Home Test Init Message • Care-of Test Init Message • Home Test Message • Care-of Test Message • Messages for Binding Update • Binding Update Message • Binding Acknowledgement Message • Binding Error Message • Binding Refresh Request Message
MIP Extensions • Mobile IPv4 (MIPv4) • Low-Latency Handover for MIPv4 (FMIPv4) • Regional Registration for MIPv4 (HMIPv4) • Mobile IPv6 (MIPv6) • Fast Handover for MIPv6 (FMIPv6) • Hierarchical MIPv6 (HMIPv6)
FMIPv6: Fast Handover for MIPv6 CN PAR NAR signaling signaling MN
FMIPv6: Operations • Handover Initiation • L2 Triggers, RtSolPr, PrRtAdv • Between MN and AR • Tunnel Establishment • HI (Handover Initiate) and HACK • Between PAR and NAR • Packet Forwarding • PAR => NAR (data buffering at NAR) • FBU, FBack • NAR => MN: • FNA (Fast NA)
HMIPv6: Overview • Motivations • Localized (Regional) Mobility Management • Hierarchical • MIP: MN HA • HMIP: MN MAP HA • MAP: Mobility Anchor Point • IP Address (CoA) • RCoA (Regional CoA): in the MAP region • LCoA (On-Link CoA): in the AR region
HMIPv6: Architecture HA CN MAP RCoA AR2 AR1 LCoA_2 LCoA_1 Movement MN
HMIPv6: Operations • MN • When entering an AR region in the MAP domain, • it gets LCoA (AR region) and RCoA (MAP region) • RCoA does not change in the MAP domain • Local Binding Update (LBU) to MAP • Bind LCoA & RCoA to MAP • MAP (Acting as a local HA) • Only the RCoA need to be registered with CN/HA • Relay all packets between MN and HA/CN
HMIPv6: MAP Tunnel (MAP MN) HA CN MAP AR2 AR1 MN Outer header Inner header MAP RCoA CN Home Addr LCoA
Proxy MIPv6 (PMIPv6) “Network-based” Localized Mobility Management
Why Network-based? • Host-based MIPv4/v6 has not been yet deployed that much. • Why host-based MIP is not deployed yet? • Too heavy specification for a small terminal • RFC 3344 (MIPv4): 99 pages • RFC 3775 (MIPv6): 165 pages • Battery problem • Waste of air resource • No Stable MIPv4/v6 stack executed in Microsoft Windows OS
PMIPv6 • IETF NETLMM WG • Internet Draft • “Proxy Mobile IPv6,” • draft-ietf-netlmm-proxymip6-00.txt (2007) • GOAL • This protocol is for providing mobility support to any IPv6 host within a restricted and topologically localized portion of the network and without requiring the host to participate in any mobility related signaling.
Technical Background • Host-based vs. Network-based Mobility HA HA Route Update Route Update AR AR Movement Movement Network-based Mobility Host-based Mobility
Proxy MIPv6 Overview LMA: Localized Mobility AgentMAG: Mobile Access Gateway IP Tunnel A IPinIP tunnel LMA and MAG. LMA Home NetworkMN’s Home Network (Topological Anchor Point) MN’s Home Network Prefix (MN-HNP) CAFE:1:/64 MAG1 Host A LMA Address (LMAA) That will be the tunnel entry-point. LMM (Localized Mobility Management)Domain MAG2 MN’s Home Network Prefix (MN-HNP) CAFE:2:/64 Proxy Binding Update (PBU) Control message sent out by MAG to LMA to register its correct location Host B MN Home Address (MN-HoA) MN continues to use it as long as it roams within a same domain Proxy Care of Address (Proxy-CoA) The address of MAG. That will be the tunnel end-point.
Proxy MIPv6 Overview • No host stack change for IP mobility • Avoiding tunneling overhead over the air • Re-use of Mobile IPv6 • PMIPv6 is based on Mobile IPv6 [RFC3775] • Only supports Per-MN-Prefix model • Unique home network prefix assigned for each MN. • The prefix follows the MN.
Proxy MIPv6 Overview • Overall Procedures • MN moves and attaches to an access router • After authentication, MAG (access router) identifies MN • MAG obtains MN’s profile containing the Home Address ..etc • MAG sends the Proxy Binding Update to LMA on behalf of MN • MAG receives the Proxy Binding Ack. from LMA • MAG sends Router Advertisements containing MN’s home network prefix • Stateless Case: MN will still configure (or maintain) the same as its home address. • Stateful Case: the network will ensure that it always gets its home address.
Proxy MIPv6 Overview In case that profile store does not have MN Home Prefix MAG emulates the MN’s home link Tunnel Setup This can be omitted when stateless configuration is used.