This document discusses wireless mesh networks (WMN) and compares various routing protocols for WMN. It covers the differences between mesh and ad-hoc networks, popular routing protocols like AODV, OSPF, HWMP, B.A.T.M.A.N, and factors to consider in WMN routing like load balancing, hop count, interference avoidance. Reactive protocols like AODV are on-demand while proactive protocols like OSPF maintain routing tables and update link states periodically. Mobile Mesh uses three separate protocols for different functions. HWMP is being developed for IEEE 802.16s WMN. Research is ongoing to find new metrics for protocols like OSPF in wireless

1. Scenario based analysis of WMN routing protocols Major Project ChiragHeda Abhishek Kona

2. Wireless Mesh Networks Cheap alternative to provide internet access in offices, public space Mesh Networking suite made available by default in One Laptop Per Child (OLPC) project Robust Networks Integration with existing networks

3. Difference between Mesh and Ad-hoc networks Ad-hoc networks A wireless ad hoc network is a decentralized wireless network. Each node is willing to forward data for other nodes, and so the determination of which nodes forward data is made dynamically based on the network connectivity Traffic flows between an arbitrary pair of nodes. Mesh networks Type of Ad-hoc network Traffic pattern to or from a gateway

4. Difference between Mesh and Ad-hoc networks Ad-hoc networks Ad hoc clients are generally user to user and not fixed to any kind of infrastructure. Mesh Networks Clients on mesh networks are dedicated to the role of routing by relying on an infrastructure of sorts

5. Difference between Mesh and Ad-hoc networks

6. Mesh Routing Protocols - Types Pro-active (table driven) Characterized by proactive checking of link state and updating of routing tables High complexity and CPU load. High performance-Low response time Eg – OSPF,OLSR,MMRP, HSLS Reactive (On-Demand) Passive reacting on detection problems (non-working routes) Less demanding on CPU. Less performing-Increased response time Eg - AODV

7. Factors to look for in WMN routing Route Load Balancing Average hop count of routes Lossy or lossless routes Avoidance of long hops Effect of interference (under study)

8. Popular WMN routing protocols AODV Mobile Mesh OSPF HWMP B.A.T.M.A.N Some effective protocols are proreitery Locust World 4G Mesh Cube Ad Hoc routing protocols extended to WMNs

9. Ad hoc On Demand Distance Vector (AODV) Developed for ad hoc networks On demand algorithm Deployed in OLPC router Reactive protocol DYMO (Dynamic On-demand MANET routing protocol) based on AODV is current research focus

10. Mobile Mesh 3 separate protocols for specific functions Link Discovery - Mobile Mesh Link Discovery Protocol (MMLDP) Routing – Mobile Mesh Routing Protocol Border Discovery – Mobile Mesh Border Dicovery protocol

11. Mobile Mesh MMRP Builds least cost path between source and destination Sends "Link State Packet" (LSP) contains information - unique router ids and costs Nodes can advertise routes, for routes having external broadband connection can advertise default routes Scalable, fish eye technique used to reduce flooding of network due to LSP Open source. Implementation available for Linux kernel

12. Open Shortest Path First (OSPF) Pro-active Metrics used to implement in WMNs ETX-Estimated Time Count metric Airtime as a metric Common implementation available, implementations with metrics not available Shortest path tree for each route is generated Sends Link State Advertisements (LSA) to all routers ETX uses no of packets lost on a route to compare routes Current research on finding new metrics for OSPF in WMNs

13. B.A.T.M.A.N(better approach to mobile ad-hoc networking) Inspired by OSLR protocol Each node perceives and maintains only the information about the best next hop towards all other nodes OGM (Originator Messages) are sent in network in selective flooding manner Global knowledge about local topology changes becomes unnecessary Deployed in many WMNs (MIT Roof Net project)

14. Hybrid Wireless Mesh Protocol (HWMP) Protocol of choice of IEEE 802.16s WMN Different channels established One single control channel established Under development, only propriety implementations available Requires 802.16s capable NICs Cross layer interaction in routing

15. References B.A.T.M.A.N http://www.openmesh.org/wiki/BATMANConcept A Secure Hybrid Wireless Mesh Protocol for 802.11s Mesh Network by Md. Shariful Islam Young Jig Yoon Md. Abdul HamidChoongSeon Hong Routing in Wireless Mesh Networks using OSPF based Airtime Metric by Chandan K Reddy, Tara P Choudhury Routing Packets into Wireless Mesh Networks by Rainer Baumann,Simon Heimlicher, Vincent Lenders, Martin May