IPv6 Mobility Support
Henrik Petander
henrik.petander@nicta.com.au
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
Identifies the network to
which host is connected
Host suffix
Identifies host within the
network.
• 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.
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.
Tunnel IPv6 hdr (CoA –HA) IPv6 hdr (HoA-CN)
Data
• 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.
Mobile IPv6 operation
Tunnel
Binding Ack.
Proxy ND for HoA
Binding Update
Router Advertisement
Router solicitation
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
NEMO (RFC 3963) Operation
Network a::
Network b::
IP IP tunnel
Network
a:1::
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?