Network Localized Mobility Management using DHCP

Network Localized Mobility Management using DHCP

[email protected]

NETLMM Problem Space

global mobility(out-of-scope)

Global Internet

NETLMMDomain A

NETLMMDomain A

NETLMMDomain B

MobileNodes

localizedmobility

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 AnchorPoint(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

MN1AR1AR1tunnel

MN1on-link

AR2

Route/Tunnel Configuration After MN moves to AR2

MN1

AR1

MN1AR2AR2tunnel

MN1on-linkAR2

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

[email protected]

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

NormalRS/RA/DHCP

Message

src=LL/Unspecdst=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

MR1MLA(MR1)MLA(MR1)tunnel

MG1

MR1defaultMLA(MG1)MLA(MG1)tunnel

MG2

Route/Tunnel Configuration after MR1 moves within MANET


MG1


MG2

Route/Tunnel Configuration after move to MG2 in same MANET


MG1


MG2

Route/Tunnel Configuration after move to MG3 in new MANET

MG1

MG2



MG3

MG2, MG3 connectedto 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)

Network Localized Mobility Management using DHCP

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