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Contents
• Problem of mobility in IP networks.• Mobile IPv6• Extensions to Mobile IPv6
Mobility background
• Mobile devices with Internet connectivity are becoming increasingly common.
• Mobile phones are becoming Internet capable.• Mobility in cellular systems and WLANs is currently
handled mostly on the link layer and is invisible to applications and Internet Protocol (IP) layer.
• Trend for multiple network interfaces in mobile devices.
IPv6 addressing and mobility
• IPv6 addresses consist of two parts: a 64-bit network prefix and a 64-bit host suffix.
• Network prefix of address depends on location.• When a host moves from one IP network to
another, it needs to change the network part of its address.→ Issues with reachability, session continuity.
Network prefix Host suffix
Identifies the network to which host is connected
Identifies host within the network.
Why do Mobility Management in IP layer
• Inter-network handoffs require changing of IP address:– Roaming between different operators networks. – Inter-technology handoffs (WLAN – GPRS/UMTS).
• Ability to choose between multiple IP networks allows a user/device to choose the best network for the situation:– Cheapest– Fastest– Best coverage
Mobile IPv6
• Mobility support in IPv6 (RFC 3775) • Mobile node (MN) is a mobile device with an IPv6
home address• Correspondent node (CN) is a computer with which
mobile node communicates using its home address.• Home Agent (HA) helps MN to manage its mobility:
– Mobile node can always be reached at its home address, regardless of its point of attachment (care-of address) to the Internet.
– Connections made with home address survive movement between different IP networks.
Mobile IPv6 addressing
• IP addresses act as both an identifier for a node and as a locator.
• Mobile IPv6 separates the identity, home address of mobile node from its locator, known as care-of address (CoA).
• Without Mobile IPv6 MN can not use its home address for sending and receiving packets when it is outside its home network.
• Mobile IPv6 uses IP-IP tunneling to create a virtual network between its CoA and HA, so that MN always appears to be in its home network.
Reverse Tunneling
• IPv6 in IPv6 tunnel is used for delivering traffic to and from home address of MN via HA.
• HA uses proxy neighbor discovery to redirect packets on home link destined to home address of MN to its own link layer address.
• HA keeps track of the care-of address of MN to deliver packets to MN.
Tunnel IPv6 hdr (CoA –HA) IPv6 hdr (HoA-CN) Data
Mobile IPv6 operation
Foreign Network
Home Network
Access Router
Home Agent
Mobile Node
Router solicitation
Binding Update
Proxy ND for HoABinding Ack.
Tunnel
Router Advertisement
MN forms Care-of address
Route Optimization in Mobile IPv6
• Tunneling of traffic between MN and CN via home agent is not efficient.– HA is a potential bottleneck– Extra routing hop increases network latency
• Route optimization (RO) allows MN and CN to communicate directly
• MN sends a BU to CN.• MN and CN use home address option and routing
header, type 2 to send packets to each other.• Route optimization is secured using return
routability protocol.
Mobile IPv6 Implementations
• Windows– MS Research implementation MN, CN, HA– MS CN implementation for Win XP– Elmic software: embedded MN
• BSD– KAME (Wide project): MN/CN/HA– INRIA: MN/CN/HA– NEC?
• Linux– MIPL (Helsinki University of Technology): MN/CN/HA– Elmic software: embedded MN
• Symbian: MN• HP-UX 11.11, 11.23 : HA/CN• Cisco: HA• Nokia: HA
Mobile IPv6 extensions
• Localized mobility management– Hierarchical Mobile IPv6 – Fast Mobile IPv6
• Context transfer to new router: Context transfer protocol
• Early discovery of new router: Candidate access router discovery protocol
Network Mobility
On-Board Network
PAN
Internet
Onboard Network
On-Board Network
Mobile Router
Access Router
Internet
Server
Home Network
Home Agent
NEMO (RFC 3963) Operation
IP IP tunnel
Network a:1::
Network a::
Network b::
References
• Mobile IPv6: RFC 3775 • Securing Mobile IPv6 MN-HA signaling: RFC 3776• Hierarchical MIPv6: RFC 4140 • Fast Mobile IPv6: RFC 4068• Context transfer protocol: RFC 4067• Candidate access router discovery protocol: RFC
4068• Network Mobility (NEMO) Basic Support Protocol:
RFC 3963
Thanks! Any questions?
