L3 in vehicular environments 2010.02.24 JinHyeock Choi Samsung AIT

Contents •

Vehicular communication overview –

•

L3 for vehicular communication –

•

Usages, entities, network topology

WAVE, CALM, C2C-CC

IPv6 over VANET (C2C NET) –

Technical issues & resolutions

Vehicle communication

ITS overview

GPS

WiMAX

802.11p

The generic Comm Architecture is CALMCALM-based

CVIS presentation

Main entities

CVIS presentation

Main entities • On-board-Unit (OBU)/ MR – Ingress & egress interfaces – Wireless in egress interface – Mobile router role • Host in egress and Router in ingress interface

Internet

RSU

• Road-side-Unit (RSU)/ AR – Upward and downward interfaces – Wireless in downward interface – Provides Internet connection – Access router role

• Application unit (AU)/ MNN

OBU

– Ordinary IPv6 nodes – Mobile network node (MNN) AU

Network Topology CN

Internet

Access Router 1

Access Router 2

MR 4 MR 3

MR 1

MNN

MNN MNN MR 2 MNN

Communication scenarios V2I CN

Internet

Access Router 1

Access Router 2

MR 4 MR 3

MR 1

MNN

MNN MNN

V2I2V MR 2 MNN

V2V

Factors affecting L3 •

Main usages – Safety  strict QoS & non-IP network protocol – Infortainment  Internet connection

•

802.11p – A 802.11 modification for vehicular environments – de-facto standard for ITS

•

Multiple communication scenarios – V2V, V2I, I2V, V2I2V – Geo-addressing & geo-routing •

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Position based routing

Several standards – Wireless Access in Vehicular Environments (WAVE) – Communications Architecture for Land Mobile environment (CALM) – Car-to-Car Communication Consortium (C2C-CC)

Current Standards

Dr. Hans-Joachim Fischer

Current L3 for vehicles CALM User Services / Applications

Combined CALM host and router

CALM FAST

Non-CALMaware

CALM IP-based

CALM service layer

CME

T-SAP

T-SAP

CALM networking layer Local port transport protocol NME

Internet ...

CALM FAST

Geo-routing

IPv6

C-SAP

C-SAP

Physical / Data Link Layer

IME

CI

CI

CI

CI

CI

CALM CIC-wl1

CALM CIC-wl2

CALM CIC-wl..

CALM CIC-wl5

CALM CIC-wr..

CALM Communications Kernel

WAVE with • Wave Short Message Protocol (WSMP) • IPv6

CALM with

C2C-CC with

• • •

•

CALM FAST Geo-routing (C2C-CC?) IPv6

•

C2C NET, a separate network protocol IPv6

Current L3 for vehicles GeoNet Approach Upper layer

IPv6

WSMP

CALM Fast

C2C NET

Lower layer

GeoNet •

Geo-addressing and geo-routing for vehicular communications (GeoNet) – – –

EU FP7 project Integrating IPv6 with Geonetworking Mainly working on IPv6 operation over C2C-CC

Primary Geonet Work Area

Design Goals • • • • • • • • •

IPv6 support Geographic data transmission Backward compatibility Security Privacy Local and global mobility Internet connectivity Migration Transparency and Seamless Mobility Separability

Main tasks • Geographic data transmission – IPv6 geonetworking shall transmit data from a vehicle to • 1) another vehicle in a certain geographic position, • 2) a set of vehicles in a certain geographic zone or • 3) any vehicle in a certain geographic zone.

– Forwarding based on geographic location • pass a packet to a neighbor nearer to the destination

• IPv6 support & Internet connectivity – Geonetworking and IPv6 are combined in such a way to realize efficient IPv6 communication. – Running IPv6 protocol (Neighbor Discovery, Address autoconfiguration) over non-ethernet link.

IPv6 configuration • Access Router 1

Internet

Router Discovery – To find a suitable access router. – To receive a Router Advertisement (RA) message with necessary information. – Periodic RA or RS/RA exchange

•

Prefix Discovery – To acquire a suitable prefix for a globally valid IPv6 address. – Prefix Information Option in RA

• Node 1

Address configuration – To configure a valid IPv6 address. – Stateless Address autoconfiguraion, DHCP, Manual.

• Node 2

DAD – To ensure the uniqueness of the configured address. – Multicast NS/ NA

IP packet delivery • CN

Involving entities – Source, Next hop, Destination – Packet is sent from source, next hop, then destination.

Internet Access Router

Node 1

•

•

IP viewpoint. – A destination can be a next hop if only it belongs to the same link. Otherwise, a default router is the next hop. – Next hop is designated with its linklayer address in MAC frame.

Node 2

Link – a communication facility or medium over which nodes can communicate at the link layer, i.e., the layer immediately below IP.

Next hop – Next hop is a node to forward packet in

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(IP) Neighbor – The nodes belong to the same link. – Next hop should be sender’s (IP) neighbors.

GeoNet network topology CN

Internet

Access Router 1

Access Router 2

MR 4 MR 3

MR 1

MNN

MNN MNN MR 2 MNN

Complications • Link – a communication facility or medium over which nodes can communicate at the link layer, i.e., the layer immediately below IP. • L2 link vs L3 link

– Link becomes fuzzy in Ad-Hoc network • No inherent link in Ad-Hoc

– No link-scope multicast. – Arbitrary link definition may cause inefficiencies or breakdown • When you change a link, you should change an IP address too. • Flooding ND messages into Ad-hoc network, wasting resources. • Inefficient data routing

Complications

Access Router 1

Access Router 2

Node 3

Node 1

Node 4

Node 2

•

Link defined as a geographic area

•

Off-link communication. – How to send a packet to a off-link destination? – If a destination if off-link, packet should go through access routers, even when the destination is directly reachable with wireless connection.

Complications • Address – For Geo-routing, geographic position should be embedded in a header, maybe directly on an address. – For vehicle, location is ever changing.

• L2/ L3 interaction – Convergence layer for 802.16 WiMAX – Address resolution et cetra

Basic assumptions • C2C NET layer – C2C-CC defines a separate network protocol with i) separate identifier, C2C NET ID and ii) separate C2C NET header with geographic information. – C2C NET layer uses position based routing and performs beaconing and location service to maintains the information about communication peers.

Upper Layer

IPv6 (NEMO)

C2C NET

• IPv6 over C2C NET layer – C2C NET layer plays the role of a lower layer of IPv6 – Inside C2C NET boundary, a packet is delivered via position based routing with C2C NET header (not depending on IPv6 header).

802.11p

C2C Packet Delivery Upper Layer

IPv6 (NEMO)

Upper Layer

Upper Layer C2C N/W

IPv6 (NEMO)

802.11p

C2C N/W

Upper Layer IPv6 (NEMO) IPv6 (NEMO) 802.11p

C2C N/W C2C N/W 802.11p 802.11p

Source

L2 neighbor

(IP) Next hop

Destination

Involving entities Destination

CN

Internet

MR 3

MR 1

MR 4

MR 2

MNN Originato r

Access Router

Involving entities • Destination

CN

Internet

Access Router IP next hop

MR 3

MR 1

MR 4 C2C NET Neighbor

MR 2

MNN Originato r

C2C NET source

•

Involving entities – Originator – C2C NET Source – C2C NET neighbor – IP Next hop – Destination Packet is – Generated at originator – Enters C2C NET VANET in C2C NET source, – Delivered to C2C NET neighbor, IP Next hop, then Destination

Involving entities • Originator – Generates IPv6 packet

• C2C NET Source – IPv6 packet enters C2C NET VANET at C2C NET source

• C2C NET Neighbor – can communicate directly each other over wireless connection. – different from (IP) neighbor in IP link.

• IP Next-hop – – – –

next node to forward packet in IP viewpoint (either a destination or AR). Destination in C2C NET viewpoint. Before IP next hop, intermediary nodes only consult C2C NET header. Only at the IP next hop, the packet’s IP header is checked to make a forwarding decision.

• Destination

Packet Encapsulation • 802.11p header: designate a C2C NET neighbor – Contains a C2C NET neighbor’s MAC address & Decapsulated at the neighbor

• C2C header: designate a IP Next hop. – Contains an IP Next hop’s C2C NET ID (with geographic location information) & decapsulated at the IP next hop.

• IPv6 header: Designate a destination – Contains a destination’s IP address & decapsulated at the destination

802.11 p header

C2C NET header

IP header

C2C NET neighbor’s MAC address

IP Next hop’s C2C NET ID

Destination’s IPv6 address

Data

Tasks • IP Next hop determination – To find an IP next hop’s IPv6 address from a destination IPv6 address.

• IP Next hop address resolution – To find a C2C NET ID of IP next hop from its IPv6 address.

• Geographic location resolution (location service) – To find a geographic location of IP next hop from its C2C NET ID.

• C2C NET neighbor determination – To find a C2C NET neighbor’s C2C NET ID (to which a packet is to be sent) from the IP next hop’s C2C NET ID & geographic location.

• C2C NET address resolution – To find a neighbor’s 802.11p MAC address from its C2C NET ID

Issues & (partial) Resolutions • IP Next hop determination – On-link determination • From the destination IPv6 address, IPv6 layer determines whether the destination is on-link or not, • i.e. the destination is directly reachable through C2C NET layer or not.

– Difficult for VANET with Geo-routing

• IP Next hop address resolution – Currently relies on ARP with link-scope multicast – No default mechanism on a link without multicast support – Binding L2 & L3 address? • MAC derived IPv6 address

– Some lower layer may be able to perform this better by itself.

Issues & (partial) Resolutions • Geographic location resolution (location service) – Resolved with existing Geo-routing mechanisms (Beaconing & flooding)

• C2C NET neighbor determination – Resolved with existing Geo-routing mechanisms (Greedy routing)

• C2C NET address resolution – Resolved with existing Geo-routing mechanisms (Beaconing)

Issues & (partial) Resolutions • Link definition – Router discovery • Broadcast area for router advertisement

– Link-scope multicast. • Shall we support link-scope multicast?

– Geographically defined area – Don’t have to define

• Address configuration & DAD – How can we configure globally valid (i.e. topologically correct) IP address on a moving car – How to ensure the uniqueness of an IP address?

Further work • Network for vehicle communication – Network protocol capable of safety application – Harmonization of diverse protocols

• IPv6 over any link – More suitable link concept • No multicast support

– L2 & L3 interworking • Address resolution or DAD

– IPv6 over 4G or IPv6 over VANET

•

IPv6 & Geo-routing integration – Embedding geographic information in IPv6 header – Position based routing algorithm

Thanks & Questions?