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Strategies For Detecting Network Attachment in Wireless IPv6
NetworksGreg Daley - Research Fellow
Monash UniversityCentre for Telecommunications and
Information Engineering
Overview:
• Tomorrow’s Wireless Internet
• Strategies for Detecting Network Attachment in IPv6
• DNA Working Group Progress
• Future Challenges
Wireless Data Communications
• Used for wide purposes– Mobile Data– Wire replacement
• Telco to SoHo– Management, Planning, Security
• Same convergence as wired networks– Merging of Internet and Telephony– Data services providing voice, voice networks
with data
Towards All IPv6 Wireless Internet
• Similar applications in Wireless to fixed
• New Applications – Peer-to-peer hampered by NAT
• IPv6 well positioned for wireless– Basic IPv6 capabilities support dynamism
Maintaining Internet Connectivity
• Cell to cell transitions can cause address changes
• Addresses are used for routing and Session Identification (TCP/UDP)
• Hide/Prevent Address changes– Tunnel, Link-Layer switching, Mobility Agents
• Manage Address changes– Addressing update, requires peer support
Maintaining Internet Connectivity
OLD CELL
NEW CELL
Address Range:2001:388:608c::/64
Address Range:3ffe:12:388:fc:/64
Change Management in Wireless IPv6
• Detect which change will occur (hard?)– Allows predictive repair
• Detect when link-layer changes
• Detect when change has occurred
• React to change– Configuration of addresses, local routers
• Signal to proxies and peers– Path restoration after change
Detecting Network Attachment
• Avoid reconfiguration if possible– Addresses, Multicast Joins, Mobility Signalling
• Detect if configuration change is required– Trade off test cost against config cost
• Query the network to detect if change has occurred
• Relies upon network information services• Single Message Pair exchange
Key DNA Tasks
• Address uncertainty management
• Response without induced delays
• Immediate Change Detection
• Authoritative Responses
Key Task: Address Management
• Host unaware of address conflicts at attachment point
• Link-Local address collision may have occurred, upon link change
• Optimistic Duplicate Address Detection is used in sending DNA messages
• New RS Tentative-Source Link-Layer Address Option: Optimistic DAD safe solicitations (GD,EN,NM)
Key Task: Fast Router Advertisement
• Existing RFCs have random delay timing
• FastRA Schemes reduce delay
• Original FastRA – manual config (MK,JK,BP)
• Deterministic – Automated config (GD,BP)
• Probabilistic – Small random delays (SN,GD)
• Hash – Speed of Det, less config (BP,EN)
RFC 2461 RS/RA TimingRouter2Router1 Router3 Host
Solicitation
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Time (s)
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T+.5
Fast Router Advertisement (RA)Router2Router1 Router3 Host
Solicitation
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Deterministic FastRARouter2Router1 Router3 Host
Solicitation
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T+.1
Probabilistic Fast RARouter2Router1 Router3 Host
Solicitation
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Time (s)
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T+.02T+.04T+.06
Hash ordered Fast RARouter2Router1 Router3 Host
Solicitation
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Time (s)
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Key Task: Link Identification
• Early work centred on numeric link-identifiers placed in each RA packet(BP,EN,GD,JHC).
• Current schemes use queries: “Is prefix aaaa::/64 on link? (BP,EN,SN)”
• Augment Prefix advertisements with learnt information (CompleteRA, Prefix LinkID )
• Message Order Independence analysis (GD,AS,BP)
Key Task: Message Authorization
• RA message authorization is built into SEND
• Separate timers for RS/RA Certificate Chain Solicit/Advert
• Last Hop certification
• Certificate solicitation in RS
• Place certificate in RA if it fits (Modified format – GD)
Detecting Network Attachment Working Group Documents
• DNA Goals
• Link Information
• DNA with unmodified routers
• DNA For IPv6 Hosts
• DNA For IPv6 Routers
• DNA Solution protocol (under discussion)
Interactions with Existing Protocols
• Link Information– Hints to start DNA from L2
• Complete Prefix Lists – Inferring Link Change with unmodified routers
• Host Operations– Initiation/After DNA
• Router management– Address Prefix and Advertisement Config
New DNA protocol modifications
• Builds on IPv6 Router Discovery
• New ND message formats, timers
• Provide single message pair exchange
• Fast Unicast RA delivery and configuration
• RA augmented for Link Identification
• Automatic Bootstrapping
IPv4/IPv6 change detection
• Dual Stack hosts accessing the Internet– Protocol Specific Mobility: MIPv4/MIPv6– Protocol Agnostic Mobility: Mobike/HIP– Transition Gateway detection
• Detecting IPv4 or IPv6 Network Services– Local Link/Subnet services– More remote services– Getting access to remote resources.
Generic Link-Layer Interfaces
• IEEE 802.21 Handoff
• Direct input of indications to DNA
• Other information
• Will generally available Link-Layer information change:– L3 Change Detection?– Mobility/Movement Management
Interface Policy interaction
• DNA is run per interface
• Limited direction for ‘Inactive’ interfaces
• DNA is Mobility Protocol Independent– Is multiple interface management?– Reasoning about local information, like DNA
DNA indications
• Path Change Indications
• End-to-End interactions
• Multiple Interfaces/Multiple Paths.