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IETF 70, 6LoWPAN WG David Culler, Geoff Mulligan, JP Vasseur 12/5/07

Architecture for IPv6 Communication over IEEE 802.15.4 subnetworks using 6LoWPAN draft-culler-6lowpan-architecture-00.txt. IETF 70, 6LoWPAN WG David Culler, Geoff Mulligan, JP Vasseur 12/5/07. Goals and Status. RFC4944 defines the format of packets used by an adaptation layer over 15.4

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IETF 70, 6LoWPAN WG David Culler, Geoff Mulligan, JP Vasseur 12/5/07

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  1. Architecture for IPv6 Communication over IEEE 802.15.4 subnetworks using 6LoWPANdraft-culler-6lowpan-architecture-00.txt IETF 70, 6LoWPAN WG David Culler, Geoff Mulligan, JP Vasseur 12/5/07

  2. Goals and Status • RFC4944 defines the format of packets used by an adaptation layer over 15.4 • Representation of compressed headers, fragmentation, intra-pan forwarding • Not how… • link mechanisms are used to implement the adaptation layer • networks using such links are organized • IPv6 capabilities are orchestrated within a PAN • Architecture draft provide an operational framework to guide realization • Status: about 3/4s done. • Additional work on LL MC cleanup, forwarding and connection to routing

  3. PAN Organization vs Link Spec or IP Architecture • org - how network admin. may elect to deploy, interconnect, configure and run the network • Complete Broadcast Domain (CBD) • important simple case that provides a baseline for how capabilities should fit together • Addressing, Standalone or IP routing to and from, ND, … • Partial Broadcast Domain (PBD) • Mesh Under – L2 forwarding and dissemination to emulate CBD • Router Over – L3 routing to interconnect BDs • Routed Mesh – L3 routing among meshed L2s

  4. 802.15.4-driven Architectural Issues • RF4944 deals with small MTU, dual (64/16) address, non-CBD • Range is not the only reason a PAN may not be a CBD • PAN_ID • Channel selection, Channel hopping • Power Cycling, Wake-up Mechanism(s) or scheduling • Interoperability involves consistent link management in addition to common format • Routing also used between distinct “links” on common phy • Variation in link quality due to external factors • Path / forwarding selection • Visibility, Loss mitigation • Draft outlines influence of these factors

  5. Addressing • Perspective is IPv6 down, rather than 15.4 up • RFC4944 - Stateless Autoconf Link Local Unicast Address • FE80::EUID64/10 • No DAD required • HC1ellided when used as IP Source or Dest • FE80::ran64/10 • Conventional DAD applies, no ellision • Additional discussion needed • Link Local Well-Known Multicast Addresses • FF02::1 – Link Local All Nodes • FF02::2 – Link Local All Routers • FF02::1:2 – Link Local All DHCP agents • Provides the means of bootstrapping the network • Organization dictates scope of these addresses

  6. Addressing – Short Addr • RFC4944 - PANID16:00:FF:FE:00:SA16 • Unique assignment of SA16, no DAD • HC1 elided when IP Source or Dest • only one SA16 per host • IPv6-based SA16 assignment Mechanisms • Stateful DHCPv6 => server provides • Stateless DHCPv6 => hostname SA16 map • Router present => DHCP agent provides • Nbr Solicitation (NS) -> Nbr Advert (DAD) • Join Link Local Solic. Node mcast FF02::1:XXXX:XXXX • Static or manual • 15.4 mechanisms • PAN coordinator – accessible PAN-wide • Access mechanism outside 6LoWPAN

  7. Link Local Multicast • Critical to IPv6 in all organizations • Mechanisms differ • FFFF vs LoWPAN_BC0 • Route Over => overlapping LL scopes • Carried in-line in HC1 • Scope => Prefix (FF01) • Group => Interface identifier (1 for allnodes) • HC1g defines SA16 form for common MCast groups but doesn’t apply in Link Local scope

  8. Routing • Necessary for external communication and connecting PANs • Permissible within PAN • Arbitrary routable IPv6 address permitted • Internal or external to PAN • HC1g elision employed for canonical forms • CGP::EUID64, CGP::xSA16 • Conventional ICMPv6 mechanisms apply • RA (router advertisement) announce presence • RS (router solicitation) to discover • Stateless DHCP for hostnames • Statefull DHCP for IPv6 addresses • DHCP delegation via agents for PBD • DNS to register mapping (if needed)

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