Mobile IPv6 & Cellular Telephony

1
Mobile IPv6 Cellular Telephony

• Charles E. Perkins
• Nokia Research Center
• Mountain View, CA USA
• http//www.iprg.nokia.com/charliep
• charliep_at_iprg.nokia.com

2
Why Mobile IP?

• Both ends of a TCP session (connection) need to
  keep the same IP address for the life of the
  session.
• IP needs to change the IP address when a network
  node moves to a new place in the network.
• Mobile IPv4 changes the mobility problem into a
  routing problem

3
Mobile IPv4 protocol overview
Home Agent
Foreign Agent
correspondent node
178.24.9.36

• Advertisement from foreign agent
• Seamless Roaming mobile node keeps home address
• Foreign agent offers care-of address
• Mobile Node always on by way of home agent

4
The Mobile IP(v4) solution

• Mobile node always uses the same IP address
  (called the home address) for communication  
• The care-of address is used for routing
• The home agent manages home network operations
  for the mobile node while it is away from home
• encapsulation
• proxy ARP
• Specified in RFCs 2002-2006

5
Foreign Agents Triangles

• The foreign agent advertises the care-of address,
  and terminates the tunnel from the home network
• All traffic to the mobile node is sent to the
  mobile node's home address. Traffic from the
  mobile node does not have to traverse the home
  network.
• This leads to the phenomenon of triangle routing.

6
Ingress Filtering

• Ingress filtering routers prevent packets from
  entering the Internet unless the source IP
  address is topologically correct.
• This leads to the possibility of reverse
  tunneling (RFC 2344) from the care-of address to
  the home agent.

7
Cellular architectures

• Involve SS7 over "control plane" to set up
  virtual circuits for "user plane" traffic
• Are highly optimized for voice traffic (low
  delay, guaranteed bandwidth), not data
• Tend toward "intelligent network" philosophy
  which for IP is a misplaced locus of control.
• Operators want to migrate towards "All-IP"
  solutions (whatever that means).

8
Mobile IPv6 Design Points

• Enough Addresses
• Enough Security
• Address Autoconfiguration
• Route Optimization
• Destination Options
• Reduced Soft-State

9
Mobile IPv6 protocol overview
Home Agent
Local Router
correspondent node
charliep_at_nokia.com

• Advertisement from local router
• Seamless Roaming mobile node keeps home address
• Address autoconfiguration for care-of address
• Binding Updates sent to correspondent nodes
• Mobile Node always on by way of home agent

10
Enough Addresses

• 340 undecillion addresses (340,282,366,920,938,463
  ,463,374,607,431,768,211,456) total
• Billions of IP-addressable wireless handsets
• Address space crunch is already evident
• recent unfulfilled request to RIPE
• Multi-level NAT unknown/unavailable
• Even more addresses for embedded wireless
• Especially interesting for China now

11
Enough Security (almost)

• Authentication Header
• Needed for Binding Update
• Remote Redirect problem
• Encapsulating Security Payload
• Required from every IPv6 node
• Key distribution still poorly understood
• PKI?
• AAA?

12
Address Autoconfiguration

• A new care-of address on every link
• Stateless Address Autoconfiguration
• Link-Local Address ? Global Address
• Stateful Autoconfiguration (DHCPv6)
• Movement Detection

Routing Prefix
MAC address
13
Destination Options

• Binding Updates without control packets
• allows optimal routing
• replaces IPv4 Registration Request messages
• Home Address option
• better interaction with ingress filtering
• supported by all IPv6 network nodes
• Binding Acknowledgement
• replaces Registration Reply

14
Route Optimization

• Reduces network load by 50
• (depending on your favorite traffic model)
• Most Internet devices will be mobile
• Route Optimization could double Internet-wide
  performance levels!
• Binding Update SHOULD be part of every IPv6 node
  implementation

15
Improved ICMP messages

• IPv4 ICMP returns only 8 payload bytes
• IPv4 home agents could not relay errors
• insufficient inner header information
• some data sources might never find out about
  broken links
• IPv6 ICMP messages return enough data
• Also used for anycast home agent discovery

16
Mobile IPv6 status

• Interactions with IPsec fully worked out
• Mobile IPv6 testing event Sept 15-17
• Bull, Ericsson, NEC, INRIA
• Connectathon last month success!
• Internet Draft is ready for Last Call
• Another bake-off likely by fall

17
AAAv4 and Cellular Telephony

• Terminology
• Protocol overview
• Key Distribution
• Scalability and Performance
• IETF Status
• How can we make it work for Mobile IPv6?

18
Terminology

• Authentication verifying a nodes identity
• Authorization for access to resources
• according to authentication and policy
• Accounting measuring utilization
• Network Access Identifier (NAI) user_at_realm
• Challenge replay protection from local
  attendant
• AAAF for foreign domain
• AAAH for home domain

19
AAA Mobile IP protocol overview
AAAF
AAAH
Local Attendant
Home Agent
charliep_at_nokia.com

• Advertisement from local attendant (e.g., router)
• Connectivity request w/MN-NAI from Mobile Node
• Local Attendant asks AAAF for help
• AAAF looks at realm to contact AAAH
• AAAH authenticates authorizes, starts
  accounting
• AAAH, optionally, allocates a home address
• AAAH contacts initializes Home Agent

20
Key Distribution

• New security model
• just one SA mobile node ?? AAAH
• So, association needed HA ?? mobile node
• TR45.6, others, want also
• local attendant ?? mobile node
• AAAH can allocate the keys for this

21
Brokers

• Needed when there are 1000s of domains
• NAI is perfect to enable this
• AAAF decides whether to use per realm
• may prefer bilateral arrangement
• iPASS, GRIC

22
Scalability and Performance

• Single Internet Traversal
• Brokers
• Eliminate all unnecessary AAA interaction
• Handoff between local attendants (routers)
• can use keys from previous router
• Regional Registration
• HA can use single care-of address per domain

23
Mobile IP/AAA Status

• AAA working group has been formed
• Taking a page from the existing model with RADIUS
  
• Mobile IP (v4) AAA requirements draft
• Last Call over
• Several 3G requirements documents online
• Mobile IP/AAA extensions draft
• AAAv6 Internet Draft(s) submitted
• stateless and stateful variations

24
Other features (needed for IPv6)

• Routers used instead as mobility agents
• Regional registration
• eliminates most location update traffic
• GGSNs/border routers are candidates
• UDP Lite
• Robust Header Compression
• AAA ?? HLR adaptation layer
• Challenge generation (not from HLR?)
• Privacy considerations

25
Hierarchical Foreign Agents
GFA
Home Agent
LFA
Home Agent stores GFA address as the Care-of
Address
Mobile Node registers only once with Home Agent
Mobile node registers locally with GFA
Often, only one level of hierarchy is being
considered
26
3GPP with GPRS
Evolution from cellular packet/GPRS
Mobility agent At GGSN
Subscription andLocation Directory
BSS
PSTN
CPS/GK
GGSN
GW
SGSN
BSC/RNC
GPRS
Internet
Call Processing Server/Gatekeeper
Traditional BSS withpacket data QoS enhancements
27
One (of many) ALL-IP visions
PSTN
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CDMA2000 3G micromobility
AAA Server
RNN
PDSN
29
CDMA2000 3G micromobility

• Terminate physical layer distant from FA
• Protected, private n/w between FA and MN
• PDSN (Packet Data Serving Node) GFA
• RNN (Radio Network Node) LFA
• RNN manages the physical layer connection to the
  mobile node

30
CDMA2000 3G Requirements

• GRE encapsulation (but will it survive?)
• Reverse Tunneling (RFC 2344)
• Registration Update
• Registration Acknowledge
• Session-specific registration extension
• contains MN-ID, type, MN Connection-ID
• contains Key field for GRE

31
CDMA2000 Registration Update

• Used for handovers to new RNN
• Acknowledgement required
• allows PDSN/old RNN to reclaim resources
• New authentication extension required
• Home address ? 0
• Home agent ? PDSN
• Care-of address ? RNN

32
IMT-2000/UMTS/EDGE reqts

• Independent of access technology
• so should work for non-GSM also
• Interoperation with existing cellular
• Privacy/encryption (using IPsec)
• QoS for Voice/IP and videoconferencing
• particular concern during handover
• Fixed/mobile convergence desired

33
IMT-2000 reqts, continued

• Charge according to QoS attribute request
• Roaming to diverse access technologies
• e.g., Vertical IP
• Route optimization
• Identification/authorization based on NAI
• Proxy registration for legacy mobile nodes
• Signaling for firewall traversal

34
IMT-2000 reqts, continued

• Reverse tunneling
• Private networks
• but, still allow access to networks other than
  the mobile nodes home network
• Dynamic home address assignment
• Dynamic home agent assignment
• even in visited network
• even when roaming from one visited network to
  another

35
IPv6 status for cellular telephony

• Seems highly likely to be mandated for 3GPP, with
  IPv4 support optional only
• MWIF recommendation for IPv6
• 3GPP2 study group favorable towards IPv6
• Seems difficult to make a phone call to a handset
  behind a NAT (not impossible, just expensive and
  cumbersome and protocol-rich)

36
Summary and Conclusions

• Future Internet is largely wireless/mobile
• IPv6 needed for billions of wireless devices
• Mobile IPv6 is far better and more efficient
• Autoconfiguration suitable for the mobile
  Internet
• Security is a key component for success
• AAA has a big role to play for cellular rollout
• Leverage from current cellular interest