An overview of Mesh Networking has been written by Tomas Krag and Sebastian B ettrich. They are wireless consultants working primarily on ways to promote the use of wireless technologies in developing countries.
Their current project, the Wireless Roadshow, deals with enabling local communities and non-profits in the developing world to plan, deploy, and maintain local, sustainable network infrastructure to enable voice and data communications, both locally and on the Internet.
They like mesh networking and list some of the reasons why:
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Price: Each mesh node runs both as a client and as a repeater potentially saving on the number of radios needed and thus the total budget.
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Ease and simplicity: If you have a box that is pre-installed with wireless mesh software and uses standard wireless protocols such as 802.11b/g, the setup is extremely simple. Since routes are configured dynamically, it is often enough to simply drop the box into the network, and attach antennas.
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Organization and business models: The decentralized nature of mesh networks lends itself well to a decentralized ownership model.
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Network robustness: Greater stability in the face of changing conditions or failure at single nodes.
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Power: Extremely low power requirements, meaning that they can be deployed as completely autonomous units with solar, wind, or hydro power.
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Integration: Mesh hardware is typically small, noiseless, and easily encapsulated in weatherproof boxes. This means it also integrates nicely outdoors as well as in human housing.
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Reality fit: Reality rarely comes as a star, ring, or a straight line. In difficult terrain — be that urban or remote — where not every user can see one or few central points, chances are she can see one or more neighboring users.
Roughly following TechTarget and Telecom Glossary 2K definitions, we define a mesh network as follows:
“A mesh network is a network that employs one of two connection arrangements, full mesh topology or partial mesh topology. In the full mesh topology, each node is connected directly to each of the others. In the partial mesh topology, nodes are connected to only some, not all, of the other nodes.”
It is beyond the scope of this article to give a comprehensive list of available protocols and systems, but the authors maintain a Wiki-page with a list of links and further reading on the subject.
In the following we will briefly introduce a couple of the most commonly seen protocols, standards, systems, and products in the world of wireless mesh.
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AODV is a routing protocol for ad-hoc networks designed with mobile wireless devices in mind. It is not subject to copyright protection and is in the public domain.
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Mobile Mesh protocol contains three separate protocols, each addressing a specific function:
- Link Discovery
- Routing
- Border Discovery
The Mobile Mesh software is covered by the GNU General Public License (Version 2).
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TBRPF, or Topology Broadcast based on Reverse-Path Forwarding, is a proactive, link-state routing protocol designed for mobile ad-hoc networks, which provides hop-by-hop routing along minimum hop paths to each destination. It seems it is patent-protected unless it becomes a IETF standard.
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OSPF is a link-state routing protocol. It is designed to be run internal to a single Autonomous System. Each OSPF router maintains an identical database describing the Autonomous System’s topology. From this database, a routing table is calculated by constructing a shortest-path tree.
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GNU Zebra is free software that manages TCP/IP-based routing protocols. It is released as part of the GNU Project, and is distributed under the GNU General Public License. It supports BGP-4 protocol as described in RFC1771 (A Border Gateway Protocol 4) as well as RIPv1, RIPv2, and OSPFv2.
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LocustWorld develops a free bootable CD solution based on the AODV protocol, and also develops and sells a complete ready-to-deploy MeshBox running its software, most (but not all) of which is available under the GPL. The MeshBox and mesh software have been used in a number of community networks in the UK.
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4g MeshCube. The German company 4G Mobile Systems has developed a tiny MeshCube running Debian Linux on a MIPS processor, using MITRE Mobile Mesh routing software. This is a ready-to-deploy gateway with both a wireless and a wired interface. With a power consumption of 4W (and potentially lower), it is ideal for deployment with an autonomous sustainable power source.
Mobile Mesh is a good starting point for mesh experiments since it can be run entirely in user space, and in our tests has worked for just about any Linux box we’ve tried it on. It also proved stable and performed OK as we dragged a mesh network out into the streets of Berlin at last autumn’s Freifunk Summer Convention — one laptop per street corner.
Qorvus’ embeds Linux Mesh software in a self-configuring and self-healing outdoor wireless networking and repeater topology
Boingo Wireless has signed a roaming agreement with mesh-enabled Verge Wireless, which operates Wi-Fi mesh networks in the Gulf South states. Verge uses mesh in its New Orleans Warehouse District network. “In addition to connectivity, we provide useful information to people at a convention or in a metropolitan area, and Wi-Fi mesh offers a means to achieve the broadest coverage cost-effectively,” said Carlo MacDonald, president of Verge Wireless.
Download a Mobile Mesh tarball from Mitre.org. Better yet, read the full article on O’Reilly first.
Sensors of the World, Unite! Smart dust will use “energy scavenging” from solar energy or vibrations and only need about 10 microwatts. The real challenge may be in pulling thousands of smart-dust motes - each with extremely constrained processing, memory and communications resources-into a distributed network that actually does something useful.
“There’s nothing new about mesh networking,” says Kristofer Pister of Smart Dust Inc; what’s “magical” is doing it with incredibly constrained-resource devices.”
How about dozens of WiFi birdhouses, meshed together, complete with little video cameras.
AA battery-powered motes are designed to report subtle changes in their immediate vicinity, bouncing the data mote-to-mote until it reaches a larger, solar-powered microserver erected on a taller pole (birdhouse) several hundred feet away. In turn, the microserver wirelessly streams the information to a more distant central processor (in this case, a PC in the reserve’s lodge), and then, via the Internet, to any interested researcher anywhere in the world.
At the moment, there are just a handful of motes in operation, at the James Reserve north of San Diego, but eventually, there will be 2,000 to 3,000 of them throughout the reserve feeding into 10 microservers. It is a field test of technology and technique run by UCLA’s Center for Embedded Network Sensing (CENS), a new research center launched with a 10-year, $40 million grant from the National Science Foundation.
“The idea is to create the means to study habitats and ecosystems in real time, down to the microlevel, without having to actually be there in the field,” say researchers. We get not just a lot more information, but we can get it down to the scale of individual plants and what animals are responding to.”
Intel Research Labs are involved in sensor networks, ubiquitous computing, environmental monitoring and PlanetLab.
