Overview

Mesh networking is a way to route data, voice and instructions between nodes. It allows for continuous connections and reconfiguration around blocked paths by "hopping" from node to node until a connection can be established.

Mesh networks are self-healing: the network can still operate even when a node breaks down or a connection goes bad. As a result, a very reliable network is formed. Applicable to wireless networks, wired networks, and software interaction.

A mesh network is a networking technique which allows inexpensive peer network nodes to supply back haul services to other nodes in the same network.

Mesh networks differ from other wireless networks in that the component parts can all connect to each other.

Types of Mesh Networks / Compatibility Issues

There are many mesh networking protocols. Some are closed source commercial and proprietary, others are standards based and open source. For the SeattleWireless project, we are only interested in Open Source protocols.

OLSR

OLSR stands for Optimized Link State Routing and is one of the most widely used mesh routing protocols. There is an RFC for OLSR, but some non standard extensions (Hysterisis, ETX) have been added to the http://olsr.org implementation and have been proven to work rather well for CommunityWirelessNetworks. OLSR has been released under the GPL, runs on Windows, OSX, Linux and *BSD, and has been packaged for OpenWRT. Because OLSR is so widely available, it is currently the preferred mesh networking protocol in SeattleWireless.

Plugins

OLSR also has a plugin architecture which includes nameservice, route visualization, dynamic gateway announcement and http info.

HSLS

HSLS stands for Hazy Sighted Link State and is in active development by the CUWireless Community Wireless Network in Champaign-Urbana Illinois. It claims to be much more scalable than OLSR and AODV, but it is not as widely ported as OLSR. It runs on NetBSD and is offered under a BSD License.

MIT RoofNet/Meraki

MIT Roofnet has put together a 50-100 node testbed in Cambridge Mass, and created the Roofnet distribution. It uses SrcRR (DSR+ETX) for routing and is the only one radio solution that natively allows a node to be both ad-hoc link as well as access point. Other mesh protocols, theoretically, can provide this functionality depending on the capabilities of the wireless chipset in use. The latest MIT Roofnet and "Meraki Networks" solutions use the Atheros Chipsets with a stripped MadWifi driver.