IPv6 integration with the ATN

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IPv6 integration with the ATN

• Tony Whyman
• Helios Information Services Ltd

2
Current Status

• The ATN SARPs specify the OSI Protocol Suite
• CLNP, TP4, ES-IS, IDRP
• Mandatory for Government Procurements in early
  1990s
• Aeronautical Industry working with IP protocol
  suite
• For Airline Passenger Services
• Possibly some Operational Services
• AEEC Project 664 Aircraft Data Networks (ADN)

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What is the Issue?

• OSI Standards no longer being developed
• IP Ground Networks cheap and available
• APC Services to use IP Protocols
• IPv6 becoming available
• Considerable Industry investment in the ATN
  Specification

4
Need for Change

• ATN must accommodate ground IP networks
• X.25 ceasing to be supported
• IPv4 in short term
• IPv6 in medium to long term
• ATN should be able to co-exist with airborne ADN
  IP systems
• Long Term Strategy needed
• Otherwise issue will keep reappearing

5
IP vs OSI

• Internet Protocol (IP)
• Transmission Control Protocol (TCP)
• User Datagram Protocol (UDP)
• Routing Protocols
• ARP, RIP, OSPF, BGP-4
• Addressing
• Interface based
• 4 byte addresses (IPv4)
• 16 byte addresses (IPv6)

• Connectionless Network Protocol (CLNP)
• Transport Protocol (TP4)
• Connectionless Transport Protocol (CLTP)
• Routing Protocols
• ES-IS, IS-IS, IDRP
• Addressing
• 20 byte System Addresses

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Key Differences

• Protocols are not mutually intelligible
• Information is encoded differently
• CLNP has a much bigger address space
• Transport connection semantics are different
• TCP has a graceful release option
• TP4 is both message and stream oriented

7
Options for Convergence (1)

• Replace OSI ATN with IP ATN
• Community investment lost
• Delays introduction of datalink services
• Invalidates current operational services
• Use IP as an ATN Subnetwork
• Ground Only at present
• An Encapsulation Strategy (CLNP inside of IP)
• Permits use of IP Networks as part of ATN
• Does not affect existing Avionics
• Or Ground End Systems

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Options for Convergence (2)

• IP to CLNP Protocol Conversion
• Permits a gradual replacement of CLNP with IP
• Independent of end-to-end communications (implies
  TP4 over IP)
• Full migration requires Application Change
• Transport Relays
• TCP to TP4 not possible in general
• ATN Dialogue Service TCP/TP4 gateway possible
• Single Point of Failure Issues

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The Ground Environment
CLNP
CLNP in End System
ATC Centre
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The IP SNDCF
CLNP
ES-IS
Other IP Service Users e.g. TCP/UDP
IP SNDCF
Other SNDCFs
IP Network
Data Link Services e.g. Ethernet, PPP, etc.
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IP SNDCF Benefits

• Simple to implement
• Can support both IPv4 and IPv6
• No impact on rest of ATN
• Allows COTS IP Networks to be part of the ATN
• Gives maximum benefit for least investment
• Specification being presented to ATNP
• Eurocontrol and STNA validating specification

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Air/Ground Environment

• Expensively produced avionics
• DO178B Level C Software Development
• Certified for Operational Use
• Long in service lifetime
• Support for Aircraft Mobility needed
• Security Requirements Include
• Separation from Passenger Systems
• Resistent to external threats

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Mobility Scenarios

• Aircraft only uses a single A/G Service Provider
• No network roaming requirement
• Aircraft serially uses multiple A/G Service
  Providers
• Strategy Required to manage transition
• Aircraft concurrently uses multiple A/G Service
  Providers
• Strategy required to manage use and route traffic
  according to policy and application requirements

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Current ATN Mobility

• Extends standard Routing Protocols
• Adds information on route QoS and A/G networks
• Meets all Scenarios
• Needs a big address space - mobility at top of
  addressing hierarchy
• Security
• Leverages off existing web of trust routing
  model

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Mobile IP
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Mobile IP and ATN

• Supports only serial use of multiple A/G Service
  Providers
• Security
• Complex dynamic three way trust model
• Requires a network wide Public Key Infrastructure
• Potential for single point of failure
• Rejected by ATNP as a model for ATN Mobility

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Airborne Convergence Options (1)

• No Change
• Retains strong separation between ATC and
  passenger communications
• Compatible with use of IP Ground Networks
• Make use of ADN IP networks where appropriate
• Extend use of IP SNDCF
• Respects differences in equipment lifecycles
• Firewalls can maintain strong separation

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Airborne Convergence Options (2)

• Replace CLNP with IPv6 in new systems
• Requires new SARPs development
• Assumes Ground Systems Migration
• Translation of ATN Mobile Routing to IP
• Requires development of new certified systems
• Requires more complex firewalls
• Compatibility with passenger systems potentially
  limited by product lifecycle differences
• Currently not under consideration

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Conclusion

• ATN will include IP Networks in its scope
• IP SNDCF is first step
• Meets most of the real requirement
• Co-existence with ADN IP Systems
• Currently under consideration
• Long Term Strategy to follow