Why do we need a routing solution for Low Power And Lossy Networks (L2Ns)

Is it too early or already too late ?

Routing Area Meeting - IETF-69 JP Vasseur/David Culler

“What are L2Ns ?”

• L2Ns: Networks comprising a large number of highly constrained devices interconnected by wireless links of unpredictable quality

Why are L2Ns so important … “This is Obvious” (Ross)

Enable New Knowledge

Improve Productivity

Healthcare

Improve Food & H20

Energy Saving (I2E)

Preventing Failures

Enhance Safety & Security

High-Confidence Transport

Health Smart Home

Is there a problem here ?

• So what?– New class of applications– New tier of devices– Networks move the bits

• Can we just consider L2Ns as “regular” IP networks and use existing protocols ?

What make L2Ns so special ?

Current Internet• An IGP has typically few

hundreds of nodes,• Links and nodes are stable,• Nodes constraints or link

bandwidth are typically non issues.

L2Ns• An order of magnitude larger

in term of number of nodes,• Links are highly unstable and

Nodes die much more often,• Unique requirements (see next

slides)

Unique Routing Requirements L2Ns

• Highly constrained devices• Harsh & dynamic environments: (variable link

qualities, link/nodes fail at a rate significantly higher than within the Internet)

• Small MTU (high error rate, limited buffer/bw)• Constraint routing is a MUST: take into account link

*and* nodes properties and constraints (also unusual)

Routing in L2Ns is a MUST for energy saving (short distances => less energy to transmit) *and* to route around obstacles (including poor quality links),

• Deep power management: WSN in sleep mode most of the time

• Highly heterogeneous capabilities

• Structured traffic patterns: P2MP, MP2P but also more and more P2P

Unique Routing Requirements L2Ns (Cont)

• Multi-path and asymmetrical load balancing

• Data aware routing: data aggregation along a dynamically computed path to a sink.

• Self-Managed !!

Unique Routing Requirements L2Ns (Cont)

Why can’t we use an existing routing protocol ?

• Many IP routing protocols have been designed: RIP, OSPF, AODV, OLSR, DYMO, TBRPF

But … • As pointed out Routing requirements for L2Ns are

unique,• None of them satisfy the minimum set of

requirements,• Some of them could be adapted/twisted/… but that

means major protocol rework.

What about MANEMO ?

• Problem: Mobile Ad-Hoc NEMO, enable a L3 mesh of NEMO mobile routers that optimizes local and global reachability.

• Quite different problem spaces. There are commonalities but also lots of differences (level of constraints, P2P, …),

• May lead to common routing protocol solutions,• RSN could be fed by MANEMO requirements and

see whether the protocol designed for L2Ns could be accommodated (WITHOUT losing the focus).

Suggested approach: do not design solutions for all L2Ns

• Research has focused on near-optimal solutions to the specific problems

• IP is maximizing interoperability, not aiming at finding a local optimum ;-)

Standardization statusNew applications pretty much every day … but …

• The number of proprietary solutions literally explodes: Zigbee, Z-Wave, Xmesh, SmartMesh/TSMP, SP100, …) at many layers (physical, MAC, L3) and most chip vendor claim to be compatible with their own standard

• Various protocol (L1/L2) to be reused such as 802.11, 802.15.4, WiMax, …

So what are the options ?

Internet

L2N

L2N

TrueMesh

Wireless HART

ISA SP100.11a

Xmesh

Znet

MintRoute

MultiHop LQI

CENS Route

Smartmesh

TinyAODV

Honeywell

What the Internet will soon look like

Do Nothing …

Issues ?

Internet

We know all of this from the 80’ and 90’

* Management complexity

* Lack of end to end consistency in term of routing, QoS, management, security, …

* Remember SNA, IPX, Vines, … or IP over ATM/FR, … ?

Multi-protocol Gateway (IP-proxy, protocol translations)L2NL2N

L2N

L2N

L2NL2N

L2N

L2N

Or … IP end to end

Internet

IP router !L2NL2N

L2N

L2N

L2N

L2N

L2N

L2N

IETF: Standardization status• 6LoWPAN (to be re-chartered soon to extend the

scope and work on discovery, management, security, …)

• 6LoWPAN WG consensus (today): L2/L3 agnostic requirements to be worked within 6lowpan and potentially given to RL2N.

• RL2N (Routing for Low Power and Lossy Networks): new mailing list where the routing issues are discussed. Several large players have joined the initiative: https://www1.ietf.org/mailman/listinfo/rsn

IETF: Standardization status

In the works:

• Routing Requirements for L2Ns: draft-culler-rl2n-routing-reqs-01

• Routing Requirement ID for Connected Home: draft-brandt-rl2n-home routing-reqs

• Routing Requirements ID for Industrial applications: in the works

• Survey on existing routing protocol applicability: draft-levis-rl2n-overview-protocols

• Routing metrics for RL2N: in the works

Key take-away …

• Stating Facts:– L2Ns are being deployed using proprietary protocols:

the need is there.– L2Ns routing requirements are unique.

So …

• Does the IETF community agree that we should be having a WG focusing on routing issues for L2Ns ?

Thanks.