Network Localized Mobility Management using DHCP

NETLMM Problem Space global mobility (out-of-scope) Global Internet NETLMM Domain A NETLMM Domain A NETLMM Domain B Mobile Nodes localized mobility

NETLMM Goals support NETLMM domains as small as a home network or as large a major operator network, e.g., metropolitan region WiFi MNs keep same addresses/prefixes as they move within a NETLMM domain (global mobility out-of-scope) support session continuity across mobility events avoid routing churn by having Mobility Anchor Points that aggregate the NETLMM domain (as opposed to tracking node mobility via a routing protocol)

NETLMM Domain Backhaul Network Access Networks Mobile Nodes (MNs) Mobility Anchor Point(s) (MAPs) Access Rtrs (ARs)

NETLMM Using DHCP Let each MN be a DHCP client Let each AR be a DHCP Relay Let each MAP be associated with a DHCP server (no need for them to be co-located)

Model of Operation MN discovers ARs via RFC2461 Router Advertisements (RAs) If RAs contain prefix options, MN can configure addresses using RFC2462, then “register” them with the network by sending DHCP Solicit/Request with IP address options If RAs contain no prefix options, or if prefix delegation is desired, MN requests prefixes by sending DHCP Solicit/Request per RFC3633 AR relays DHCP Solicit/Request to a DHCP server associated with a MAP

Model of Operation (cont’d) DHCP server registers addresses/prefixes, then issues “create tunnel”; “route add” to update MAP IP forwarding table(s) DHCP server sends reply to MN which is intercepted by AR; AR performs a local “route add” Now, traffic from the Internet destined to MN flows through the MAP(s) and is directed to the correct AR If MN moves to a new AR, MN issues a DHCP Confirm which causes the MAPs and ARs to update their IP forwarding tables

Route/Tunnel Configuration after MN config’s address/prefix via AR1 MN1 AR1 MN1  AR1 AR1  tunnel MN1  on-link AR2

Route/Tunnel Configuration After MN moves to AR2 MN1 AR1 MN1  AR2 AR2  tunnel MN1  on-link AR2

Additional Considerations Works with IPv4 as well as IPv6 (IPv6 has some advantages) Supports DHCPv6 prefix delegation (delegated prefixes move along with the MN) tunnels from MAPs to ARs can be unidirectional Explicit messaging between MAPs and ARs might be better than implicit route add/delete based on DHCP messages – being worked in IETF NETLMM wg

Additional Considerations (cont’d) With multiple ARs on the link, ambiguous as to which AR is selected in MAP forwarding tables – MN can assert AR selection by sending L3 multicast DHCP Solicit/Request to unicast L2 address of a specific AR global addressing goes through MAPs, but efficient local communications can be supported using IPv6 ULAs (could result in dropped calls) Since MNs can move freely between access networks, Redirects could cause dropped calls. ARs on NETLMM links should therefore not send redirects.

Issues can DHCP Confirm be used to test whether a delegated prefix is appropriate for the new link. If not, why not? with all global addresses/prefixes delegated by DHCP server, no need for DAD on NETLMM links? link-local addresses can also be registered with DHCP server. Again, no need for DAD?

MANET Autoconfiguration using DHCP

MANET Autoconf Problem Space Provide Network(s) MANETs MANET Gateways (MGs) MANET Routers

MANET Routing Alternatives MANET routing as a L2 mechanism w/no L2 multicast flooding – MANET looks like an NBMA link that connects routers/gateways (no gateway discovery; not considered further) MANET routing as a L2 mechanism w/L2 multicast flooding - MANET looks like a bridged campus LAN (no special MANET Autoconf extensions needed) MANET routing as a L3 mechanism w/no L3 multicast flooding – MANET looks like multiple links w/no multicast (no gateway discovery; not considered further) MANET routing as a L3 mechanism w/L3 multicast flooding – MANET looks like multiple links w/MANET- wide (site-scoped) multicast (subject of this proposal)

MANET Autoconf Goals MANET Routers (MRs) must be able to discover MANET Gateways (MGs) even if they are multiple L3 hops away MRs must be able to obtain global IP address/prefix delegations support for multiple MGs support for intra- and inter-MANET mobility for MRs Support for both IPv6 and IPv4

MANET Autoconf Using DHCP Let each MR and MG configure a MANET Local Address (MLA) for routing protocol operation; local communications (for IPv6, likely to be RFC4193 ULAs) Let each MR be a DHCP client Let each MG be a DHCP Relay/Server Let there be a means for MRs and MGs to send “Extended” RS, RA and DHCP messages

Extended RS, RA and DHCP Msgs normal RS/RA/DHCP message configured per RFC2461, RFC3315, RFC3633 message encapsulated in outer IP header with: –src = MLA of sender –dst = Site-scoped multicast, or MLA of target –Hop Limit = small integer value (e.g., 2, 5, 10) message “tunneled” to one or more recipients

Extended RS, RA and DHCP Msgs Normal RS/RA/DHCP Message src=LL/Unspec dst=All_*_Multicast Hop Limit = 255 src=MLA(sender) dst=Site-scope Multicast or MLA(target) Hop Limit = 2,5,10,etc Message Inner IP header Outer IP header

Model of Operation MR discovers MGs via Extended RAs (ERAs) (MR sends ERSs if necessary) If ERAs contain prefix options, MR can configure addresses using RFC2462, then “register” them with the network by sending Extended DHCP Solicit/Request with IP address options If ERAs contain no prefix options, or if prefix delegation is desired, MR requests prefixes by sending Extended DHCP Solicit/Request per RFC3633 MG decapsulates the Extended DHCP Solicit/Request and relays it to a local DHCP server or a server in the provider network

Model of Operation (cont’d) DHCP server sends reply to MR which is intercepted by MG; MG performs a “route add” and “create tunnel” for MR MR receives the DHCP reply and performs a “route add” and “create tunnel” for MG Now, packets from the Internet destined to MR are directed to MG which tunnels them to MR, and packets from MR destined to the Internet are tunneled to MG If MR moves to new MG, it sends an Extended DHCP Confirm which causes MGs to update their IP forwarding tables

Route/Tunnel Configuration after MR1 conf’s address/prefix via MG1 MR1  MLA(MR1) MLA(MR1)  tunnel MG1 MR1 default  MLA(MG1) MLA(MG1)  tunnel MG2

Route/Tunnel Configuration after MR1 moves within MANET MR1  MLA(MR1) MLA(MR1)  tunnel MG1 MR1 default  MLA(MG1) MLA(MG1)  tunnel MG2

Route/Tunnel Configuration after move to MG2 in same MANET MR1  MLA(MR1) MLA(MR1)  tunnel MG1 MR1 default  MLA(MG2) MLA(MG2)  tunnel MG2

Route/Tunnel Configuration after move to MG3 in new MANET MG1 MG2 MR1  MLA(MR1) MLA(MR1)  tunnel MR1 default  MLA(MG3) MLA(MG3)  tunnel MG3 MG2, MG3 connected to same provider

Additional Considerations Compatible with “NETLMM using DHCP” Works with IPv4 as well as IPv6 (IPv6 has some advantages) For IPv4, need a new option (“MLA Option”) to inform relay of MR’s MLA for last-hop forwarding purposes Supports DHCPv6 prefix delegation (delegated prefixes move along with the MN) tunnels from MGs to MRs are bi-directional (but, tunneling from MR to MG can be omitted if “default” is propagated through MANET)