Mesh Networks

Basic Definition and Benefits

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Mesh networks are networks that are, in a sense, "meshed" together. In a typical network, many nodes are connected to one gateway, typically a router, that connects those nodes to the Internet. These nodes are usually not connected to each other in any real way. To contrast, a mesh network maintains connections between all the nodes in said network. Because many networking implementations make extensive use of graph theory, it is prudent to sometimes inject graph theoretical terminology to describe certain network topologies. A mesh network is a connected graph, whereas the aforementioned "typical" network is more likely a star graph (bipartite).

The benefit of this node connectedness is that if one connection fails between nodes, those nodes can still connect by taking another route (there are cycles in the graph). This allows for high network dependency. This also dovetails into another important positive aspect of mesh networks: they are decentralized. If one node in the mesh fails, the network stays intact.

Other benefits include ease of and relatively low cost of implementation, particularly suiting this networking strategy to rural areas that are deemed too risky/expensive for ISPs to provide network infrastructure for.

Existing Mesh Projects

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SMesh, an experimental Mesh Network developed at Johns Hopkins University

Freifunk, German for "free radio"

Resources for constructing Mesh Networks

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SMesh's accepted publication on their implementation

A DIY guide to building your own Freifunk-based mesh network

Recommended Reading

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A technically flavored layman's guide to mesh networking

Resources

• Freifunk

• CUWin

• wire.less.dk

• Maraka institute

• Shuttleworth foundation

• openWRT

• EWRT

• DD-WRT

• Afrimesh

Questions

• How do radios work?

• What is our frequency?

802.11 b/g => 2.4 GHz

• Is there frequency pollution?

• How much ground per node?

• Thick or thin?

• What Software will we use?

see below

• What hardware will we use?

see below

• How many?

2 + 2

• Where will we put them?

on roofs of buildings- Noyce, German House etc.

• Can we use antennae/dishes/amplifiers?

yes- see Freifunk articles about antennae

Features

• Range (Tx/Rx)

• Frequency

• Data Throughput

• interface

• power consumption

• weatherization

• USB port

Possible Hardware Choices

• Linksys WRT54GL
  • cca $50
  • 802.11b/g
  • no USB
  • removable antenna
• Linksys WRT54GS
  • $50
  • no USB
  • more powerful than WRT54GL because contains Speedbooster
• Linksys WRTSL54GS
  • cca $50
  • hard to find
  • similar to WRT54G, but with USB
  • non-removable antenna
• ASUS WL-520gU
  • cca $45
  • 802.11b/g
  • with USB
• Ubiquiti Nanostation
  • cca $50
  • 802.11b/g
  • supports passive Power Over Ethernet
• D-link DIR-300
• Asus Wl5006

Mesh Node Software

• OpenWRT or DD-WRT, Linux distributions for embedded systems
• B.A.T.M.A.N. or OLSR, routing protocols
• Firmware Plugins (i.e. Apple Bonjour)
• Freimap, a visualization and analysis environment for community mesh networks
• horst tool, a scanning and analysis tool for 802.11 wireless networks