ipv6 integration with the atn tony whyman helios information services ltd
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Current Status
The ATN SARPs specify the OSI Protocol Suite
CLNP, TP4, ES-IS, IDRPMandatory for Government Procurements in early 1990s
Aeronautical Industry working with IP protocol suite
For Airline Passenger ServicesPossibly some Operational ServicesAEEC Project 664 Aircraft Data Networks (ADN)
What is the Issue?
OSI Standards no longer being developedIP Ground Networks “cheap” and availableAPC Services to use IP ProtocolsIPv6 becoming availableConsiderable Industry investment in the ATN Specification
Need for Change
ATN must accommodate ground IP networks
X.25 ceasing to be supportedIPv4 in short termIPv6 in medium to long term
ATN should be able to co-exist with airborne ADN IP systemsLong Term Strategy needed
Otherwise issue will keep reappearing
IP vs OSIInternet Protocol (IP)
Transmission Control Protocol (TCP)User Datagram Protocol (UDP)Routing Protocols
ARP, RIP, OSPF, BGP-4
AddressingInterface based4 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
Addressing20 byte System Addresses
Key Differences
Protocols are not mutually intelligibleInformation is encoded differently
CLNP has a much bigger address spaceTransport connection semantics are different
TCP has a graceful release optionTP4 is both message and stream oriented
Options for Convergence (1)Replace OSI ATN with IP ATN
Community investment lostDelays introduction of datalink servicesInvalidates current operational services
Use IP as an ATN SubnetworkGround Only at presentAn Encapsulation Strategy (CLNP inside of IP)Permits use of IP Networks as part of ATNDoes not affect existing AvionicsOr Ground End Systems
Options for Convergence (2)
IP to CLNP Protocol ConversionPermits a gradual replacement of CLNP with IPIndependent of end-to-end communications (implies TP4 over IP)Full migration requires Application Change
Transport RelaysTCP to TP4 not possible in generalATN Dialogue Service TCP/TP4 gateway possibleSingle Point of Failure Issues
The Ground Environment
ATC Centre
CLNP
IPv4 or IPv6 Internet
CLNPATC Centre
IPv4 or IPv6 Internet
ATC Centre
CLNP inEnd System
The IP SNDCFCLNP
IP SNDCF
IP Network
Other IP ServiceUsers e.g. TCP/UDP
Data Link Servicese.g. Ethernet, PPP, etc.
Other SNDCFs
ES-IS
IP SNDCF Benefits
Simple to implementCan support both IPv4 and IPv6No impact on rest of ATNAllows COTS IP Networks to be part of the ATNGives maximum benefit for least investmentSpecification being presented to ATNP
Eurocontrol and STNA validating specification
Air/Ground Environment
Expensively produced avionicsDO178B Level C Software DevelopmentCertified for Operational UseLong in service lifetime
Support for Aircraft Mobility neededSecurity Requirements Include
Separation from Passenger SystemsResistent to external threats
Mobility ScenariosAircraft 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
Current ATN Mobility
Extends standard Routing ProtocolsAdds information on route QoS and A/G networksMeets all ScenariosNeeds a big address space - mobility at top of addressing hierarchy
SecurityLeverages off existing “web of trust” routing model
Mobile IP and ATN
Supports only serial use of multiple A/G Service ProvidersSecurity
Complex dynamic three way trust modelRequires a network wide Public Key Infrastructure
Potential for single point of failureRejected by ATNP as a model for ATN Mobility
Airborne Convergence Options (1)
No ChangeRetains strong separation between ATC and passenger communicationsCompatible with use of IP Ground Networks
Make use of ADN IP networks where appropriate
Extend use of IP SNDCFRespects differences in equipment lifecyclesFirewalls can maintain strong separation
Airborne Convergence Options (2)
Replace CLNP with IPv6 in new systemsRequires new SARPs developmentAssumes Ground Systems MigrationTranslation of ATN Mobile Routing to IPRequires development of new certified systemsRequires more complex firewallsCompatibility with passenger systems potentially limited by product lifecycle differencesCurrently not under consideration