Phil Levis, Stanford Univ. JP. Vasseur, Cisco Systems David Culler, UC Berkeley

1. Overview of Existing Routing Protocols for Low Power and Lossy Networksdraft-levis-roll-overview-protocols-00 Phil Levis, Stanford Univ. JP. Vasseur, Cisco Systems David Culler, UC Berkeley IETF 70 ROLL WG Meeting

2. Goal (1) • Provide a discussion platform for building a rough consensus around the suitability, ill-suitability, and technical trade-offs in utilizing existing IETF protocols for Routing Over Low-power and Lossy networks.

3. In pictures Future Existing Protocols “roll proto” 3. Link State Protocols 3.1. OSPF 3.2. OLSR 3.3. TBRPF … … 4. Distance Vector protocols 4.1. RIP 4.2. DSDV 4.3. AODV 4.4. DYMO 4.5. DSR . . . . … Overview ID Common understanding of basis for analyzing alternatives and rough consensus on assessment

4. Goal (2) • Provide a discussion platform for building a rough consensus around the suitability, ill-suitability, and technical trade-offs in utilizing existing IETF protocols for Routing Over Low-power and Lossy networks. • Not to design a final protocol, but a baseline and framework for the process of defining one.

5. Crit 0 Crit 1 Crit 2 Crit 3 … 3. Link State 3.1. OSPF 3.2. OLSR 3.3. TBRPF … 4. Distance Vector 4.1. RIP 4.2. DSDV 4.3. AODV 4.4. DYMO 4.5. DSR … Outcome Rough Consensus on the Criteria Quantitative and qualitative Rough Consensus on the Analysis

6. Application Domain Requirements Simplifications The Technical Task … low rate … … scalability… Routing over Low-Power & Lossy Constraints Challenges Technological

7. Preliminary Analysis Use Ctrl Routing ovhd state 3. Link State 3.1. OSPF wired O(NNdc) O(Nd) 3.2. OLSR wireless O(NN) O(Nd) 3.3. TBRPF wireless O(NN) O(Ndd) … 4. Distance Vector 4.1. RIP wired O(ND) O(D) 4.2. DSDV wireless O(NCc) O(Cd) 4.3. AODV wireless O(ND) O(D) 4.4. DYMO wireless O(NCch) O(Ch+d) 4.5. DSR wireless O(NNdh) O(Dh) … • N – nodes • C – communicating nodes • P – pairs (active routes) • D – destinations • d – degree (denisty, nbrs) • c – link churn • h – hops (diameter, route length) … just to get discussion ROLLing

8. What’s different in ROLL?

9. Routing • … exchange of information to establish and maintain local tables such that each node can compute • next hop, IF := R(destination) • in a manner consistent with the underlying connectivity graph IF := R(d)

10. Wireless (nLP, nL) Routing • No a priori underlying connectivity graph • a link exists if it works when you try it • “self-organization”, discovery • Next hop is a neighbor node selection • nbr set may vary in time due environmental effects, movement, interference, obstacles, other communication, … • Topology is determined by physical placement • e.g, impact on d? …of d?

11. Parameters (first pass) • N (Nodes): # points of interest • d (degree): density of deployment / range • max degree may be huge • h (hops): physical extent / range • c (churn): environmental factors • C (Communicators): active portion • D (Destinations): concentration of flows

12. Constraints • Low Power • lifetime, physical size, rate of activity, cost, applicability, … all dictated by power consumption • Short range, high loss rate, small MTU, low rate links • Low (ave) data rates typical • Routing protocol rate must be << application rate • Routing protocol comm. costs matter • Discovery, maintenance, repair, … • Computed wrt deployment characteristics • N, d, h, c, C, D, …

13. Constraints • Low Power • Footprint • microcontrollers (outnumber microprocessors 25:1) typically have kilobytes of memory, not megabytes or gigabytes. • $s • ram $0.40/kb, 100x sram, 10,000x dram • Standby power (which dominates in low duty cycle) determined by leakage • MB ram => discarded in sleep, restored on wake • All routing state matters • route tables, neighbor tables, caches, DBs, buffers • N, d, h, c, C, D • Summarization, partial information, …

14. Challenges • Lossy • Low Transmit Power • Low SNR, short range [d?, h?] • Low sensitivity • Physical attenuation, occlusion, interference, motion • generally cannot move the node to make the network happy • Receiver diversity, in addition to temporal, frequency, spatial • loss is typical, not exceptional • often transient, not necc. excess data rate [c?] • typically, should not trigger costly repair • Loss  No Link • Reception  Link present • Multiple paths permit local rerouting • Scale is often very large

15. Rock and ROLL • Requires rigorous routing protocol design • Can’t just throw resources at it. • Can’t just throw bandwidth at it. • Must use prolonged observation, not instantaneous. • Faces same concerns as embedded applications • ROLL operates “between a rock and a hard spot”

16. Can we tackle such a hard problem? • Lots of existence proofs in the industry today • Application domains introduce important simplifications • The “not required” or “infrequent” is as important as the “is required” • Routing Requirement drafts are defining these • This draft represents them parametrically • Example • Vast majority of flows are in to and out of a single (or few) points [ D?, C?, P?] • Minority of mobile nodes within static extent • …

17. Start of a Process • Important to have a analysis template to gain consensus on the relevant parameters, the criteria and the analysis across protocols • Each entry in the table will have considerable supporting evidence • Goal is common understanding of facts, not “winning the match”. • There may be no “winner” but important lessons learned from each entrant. • No “sacred cows” assumed. • Expect an active, interactive exchange between Phili and Dublin