mobile ipv6 & cellular telephony
DESCRIPTION
Mobile IPv6 & Cellular Telephony. Charles E. Perkins Nokia Research Center Mountain View, CA USA http://www.iprg.nokia.com/~charliep [email protected]. Why Mobile IP?. Both ends of a TCP session (connection) need to keep the same IP address for the life of the session. - PowerPoint PPT PresentationTRANSCRIPT
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Mobile IPv6 & Cellular Telephony
Charles E. Perkins
Nokia Research Center
Mountain View, CA USA
http://www.iprg.nokia.com/~charliep
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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
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Mobile IPv4 protocol overview
• 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
Foreign Agent
178.24.9.36
Home Agent
correspondent node
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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
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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.
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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.
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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…).
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Mobile IPv6 Design Points
• Enough Addresses
• Enough Security
• Address Autoconfiguration
• Route Optimization
• Destination Options
• Reduced Soft-State
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Mobile IPv6 protocol overview
• 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
Local Router
Home Agent
correspondent node
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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
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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?
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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
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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
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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
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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
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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
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AAAv4 and Cellular Telephony
• Terminology
• Protocol overview
• Key Distribution
• Scalability and Performance
• IETF Status
• How can we make it work for Mobile IPv6?
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Terminology
• Authentication – verifying a node’s identity• Authorization – for access to resources
– according to authentication and policy
• Accounting – measuring utilization• Network Access Identifier (NAI) – user@realm• Challenge – replay protection from local attendant• AAAF for foreign domain• AAAH for home domain
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AAA & Mobile IP protocol overview
• 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
AAAF AAAH
Local AttendantHome Agent
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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
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Brokers
• Needed when there are 1000’s of domains• NAI is perfect to enable this• AAAF decides whether to use per realm
– may prefer bilateral arrangement
• iPASS, GRIC
AAAHAAAF
Local AttendantHome Agent
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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
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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
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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
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Hierarchical Foreign Agents
Home Agent
GFA
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
LFA
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3GPP with GPRS
InternetInternet
PSTN
HSS
Subscription andLocation Directory
Call ProcessingServer/Gatekeeper
CPS/GK
SGSN
Evolution from cellular packet/GPRS
BSC/RNC
BSS
GGSN
GPRS
GW
Traditional BSS withpacket data QoS enhancements
Mobility agentAt GGSN
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One (of many) “ALL-IP” visions
PSTN
HA(mobility within
serving ntw)
HA
FW
AAA Server AAA Server
Internet, Intranets
Subscriberdatabase
FW
CPS
GW
"Slim RNC/BSC"
Evolution from general IP networks
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CDMA2000 3G micromobility
AAA Server
HA
AAA Server
Subscriberdatabase
PDSN
RNN
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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
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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
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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
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IMT-2000/UMTS/EDGE reqt’s
• 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
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IMT-2000 reqt’s, 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
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IMT-2000 reqt’s, continued
• Reverse tunneling• Private networks
– but, still allow access to networks other than the mobile node’s home network
• Dynamic home address assignment• Dynamic home agent assignment
– even in visited network– even when roaming from one visited network to
another
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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)
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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