Mesh Networks

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Meshworks are networks of devices which connect to each other without prior infrastructure. They are also called viral communicators.


Definition

1.

"Mesh networks - are highly distributed networks which use special routing technology. In standard routing technology as used to send and receive information via the internet the 'routes' which data packets take are fixed. In mesh networks the software decides 'dynamically' or 'ad-hoc' which route data packets take. Sometimes 'mesh networking' and 'ad-hoc networking' are used as synonyms. In wireless and mobile networks mesh networking has the obvious advantage that the software adapts dynamically to changes in the structure or 'topology' of the network. There are a number of routing protocols which support mesh networking amongst which OLSR is one of the most advanced and most widely used ones."


2. PRIMAVERA DE FILIPPI:

"An ad hoc network infrastructure that can be set up by anyone, mesh networks wirelessly connect computers and devices directly to each other without passing through any central authority or centralized organization (like a phone company or an ISP). They can automatically reconfigure themselves according to the availability and proximity of bandwidth, storage, and so on; this is what makes them resistant to disaster and other interference. Dynamic connections between nodes enable packets to use multiple routes to travel through the network, which makes these networks more robust.

Compared to more centralized network architectures, the only way to shut down a mesh network is to shut down every single node in the network.

That’s the vital feature, and what makes it stronger in some ways than the regular internet." (http://www.wired.com/2014/01/its-time-to-take-mesh-networks-seriously-and-not-just-for-the-reasons-you-think/)

Description

From a summary in Technology Review:

"Meshies believe that mesh networks will overthrow traditional networking and communications and create entirely new kinds of distributed software. For the purposes of this column, mesh networks (sometimes called mobile ad hoc networks, or MANETs) are local-area networks whose nodes communicate directly with each other through wireless connections. It is the lack of a hub-and-spoke structure that distinguishes a mesh network. Meshes do not need designated routers: instead, nodes serve as routers for each other. Thus, data packets are forwarded from node to node in a process that network technologists term "hopping."

Before dismissing mesh networks as being of interest only to specialists, consider their advantages over existing hub-and-spoke networks. Mesh networks are self-healing: if any node fails, another will take its place. They are anonymous: nodes can come and go as they will. They are pervasive: a mobile node rarely encounters dead spots, because other nodes route around objects that hinder communication. Meshes are cheap, efficient, and simple. But they are still in development. The chief technical challenge for meshes is the inherent unreliability of wireless links. Because the unreliability compounds with each hop, the size of meshes is now limited. A related problem with hopping is that, for now, moving nodes seldom establish new connections "seamlessly": when a network's topology changes, some transmission paths can be temporarily disrupted. Therefore, voice and video sit unhappily on meshes. Meshes lack standards, too: low-bit-rate mesh networking has a standard called ZigBee that is supported by around 100 companies, including Motorola, Mitsubishi, Phillips, and Samsung, but high-bit-rate communications have no such standard (although the 802.11 committee of the Institute of Electrical and Electronics Engineers hopes to create one by next May).

What does all this mean? A few, early applications of mesh networks are already emerging. Meshes will allow municipalities to create cheap or free urban Wi-Fi networks (we will be writing about Philadelphia's effort in our November issue). Meshes have obvious advantages for military and security personnel who want networks that are unbreakable and "horizontal" (see "Instant Networks," June 2005). Environmental scientists like meshes because they can provide continuous data from large geographical areas over many years (see "Casting the Wireless Sensor Net," July/August 2003). But the most important application of meshes will be in what technologists once called "pervasive computing": embedding sensors and processors in things like clothes, electronics, and buildings and connecting them into smart networks.

But I believe that the most intriguing aspect of mesh networks is their cybernetic qualities. That is, mesh networks are adaptive systems that resemble biological systems (we recently wrote about MIT mathematics professor Norbert Wiener, the founder of cybernetics: see "Cybernought," June 2005). Many meshies like to say that they draw their inspiration from the behavior of swarming bees or ants." (http://www.technologyreview.com/articles/05/09/issue/editor.asp?trk=nl)


Advantages

Privacy

Primavera de Filippi:

"For these concerned about the erosion of online privacy and anonymity, mesh networking represents a way to preserve the confidentiality of online communications. Given the lack of a central regulating authority, it’s extremely difficult for anyone to assess the real identity of users connected to these networks. And because mesh networks are generally invisible to the internet, the only way to monitor mesh traffic is to be locally and directly connected to them." (http://www.wired.com/2014/01/its-time-to-take-mesh-networks-seriously-and-not-just-for-the-reasons-you-think/)


Community Governance

Primavera de Filippi:

"Yet beyond the benefits of costs and elasticity, little attention has been given to the real power of mesh networking: the social impact it could have on the way communities form and operate.

What’s really revolutionary about mesh networking isn’t the novel use of technology. It’s the fact that it provides a means for people to self-organize into communities and share resources amongst themselves: Mesh networks are operated by the community, for the community. Especially because the internet has become essential to our everyday life.


Instead of relying on the network infrastructure provided by third party ISPs, mesh networks rely on the infrastructure provided by a network of peers that self-organize according to a bottom-up system of governance. Such infrastructure is not owned by any single entity. To the extent that everyone contributes with their own resources to the general operation of the network, it is the community as a whole that effectively controls the infrastructure of communication. And given that the network does not require any centralized authority to operate, there is no longer any unilateral dependency between users and their ISPs.

Mesh networking therefore provides an alternative perspective to traditional governance models based on top-down regulation and centralized control.

Indeed, with mesh networking, people are building a community-grown network infrastructure: a distributed mesh of local but interconnected networks, operated by a variety of grassroots communities. Their goal is to provide a more resilient system of communication while also promoting a more democratic access to the internet." (http://www.wired.com/2014/01/its-time-to-take-mesh-networks-seriously-and-not-just-for-the-reasons-you-think/)


Status

May 2009:

"Mesh networking as a broad-based approach to networking is growing. A mesh network with 240 nodes covers Vienna. Similar projects are underway in Barcelona, Athens, the Czech Republic and, before long, in two areas of Boston not far from the cafe we’re sitting in. But the most dramatic examples are the battlefields of Iraq and Afghanistan.

“Today in Iraq and Afghanistan, soldiers and tanks and airplanes are running around using mesh networks,” said Chase. “It works, it’s secure, it’s robust. If a node or device disappears, the network just reroutes the data.” (http://www.wired.com/autopia/2009/05/the-grid-our-cars-and-the-internet-one-idea-to-link-them-all/)

Applicatons

Mesh Networks or Ad Hoc Networks for the telecom sector, as described in The Economist:

"The mesh-networking approach, which is being pursued by several firms, does this in a particularly clever way. First, the neighbourhood is “seeded" by the installation of a “neighbourhood access point" (NAP)—a radio base-station connected to the Internet via a high-speed connection. Homes and offices within range of this NAP install antennas of their own, enabling them to access the Internet at high speed.Then comes the clever part. Each of those homes and offices can also act as a relay for other homes and offices beyond the range of the original NAP. As the mesh grows, each node communicates only with its neighbours, which pass Internet traffic back and forth from the NAP. It is thus possible to cover a large area quickly and cheaply." (http://www.economist.com/printedition/displayStory.cfm?Story_ID=1176136


Examples

  1. Freifunk, Germany

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


Discussion

Why Open Mesh Networks are beneficial

1) Mark Cooper:

"The technologies at the heart of the digital revolution are also at the heart of the deployment of open wireless networks in the spectrum commons. The potential spectrum carrying capacity has been the direct beneficiary of the convergence of progress in digital technology and the institutional development of networks. When users add radios that help by cooperating in receiving and forwarding signals, i.e. act as repeaters, carrying capacity of the network increases. Smart nodes get their expanding brainpower from decentralized computational capacity to communicate seam-lessly, utilizing embedded coordination protocols.

Smart technologies in mesh networks cooperating to deliver messages also show the beginning of anti-rivalry characteristics. The ability of each node to receive and transmit messages, even when they are neither the origin nor the destination, expands the capacity of the network. This intelligence is the key to mesh networks’ immense capacity.

The Spectrum Commons in which these networks exist exhibits the characteristic of inclusiveness, since the more nodes on the net-work, the greater the value to users. The denser the nodes in the commons, the greater is the commons’ communications capacity. The combination of digital technology and network organization has turned the old logic on its head; adding users on a mesh network improves performance. Mesh Networks allow devices to share their resources dynamically, allowing more communications to take place with less power.

However, even with new technology, there is still the challenge of how to ensure cooperation among users. Since cooperation is the key to the capacity gain, if users chose not to cooperate, the mesh network will not work. Therefore, more devices are transitioning to “embed coordination” to ensure cooperation. For example, radios become smart by embedding intelligence – algorithms – that take on the functions necessary to transmit a signal after listening to the spectrum and finding available frequencies to use and determining the power necessary." (http://cyberlaw.stanford.edu/system/files/From+Wifi+to+Wikis+and+Open+Source.pdf)


2. Why the interest in mesh?

"There are four major benefits:

-- Range extension is one of the primary arguments for mesh networks. In situations where wired access-point connectivity is too expensive to implement or impractical due to environmental conditions, the ability to deploy a node that can receive and forward traffic can make wireless mesh the only solution. Because wired infrastructure is not required, mesh can be set up faster, cheaper and with less expertise.

-- Mesh nodes can be deployed anywhere there is power, with the resulting network architecture providing better coverage. Nodes can be put in with no regard to the wired backbone. The only limitation is power and radio propagation. Due to the properties of radio-frequency propagation, higher capacity is an added benefit. The closer the radio links between nodes, the higher the modulation rate. The higher the modulation rate, the higher the effective network throughput. Without mesh this can only be achieved with expensive and complicated antenna technology. In the mesh network, any standard off-the-shelf client is able to achieve the highest possible throughput.

-- A wireless mesh inherently is more resilient and fault tolerant than a centralized infrastructure network. Provided there are a sufficient number of nodes, the network is able to sustain temporary congestion, individual node failure and localized interference. The built-in ability to find neighbor nodes, set up connections, find optimal traffic paths -- all these standard features make the products based on 802.11s mesh less failure-prone.

-- Mesh devices can be set up to create a high-bandwidth network among themselves without the need for a central access point. This ability for peer-to-peer connectivity opens a host of new applications in the enterprise and home markets." (http://www.misweb.com/magarticle.asp?doc_id=26454&rgid=5&listed_months=0)

Meshworks are different from P2P Networks

As far as I understand the distinction, P2P works on the existing infrastructure, which may or not be P2P itself, while meshworks create a new infrastructure which is much more thoroughly distributed.

From a discussion of a Technology Review article at http://www.technologyreview.com/Infotech/18284/page1/

"In a P2P network, the physical infrastructure still looks like a tree, but the bandwidth is more efficiently employed because underutilized branches can become content distributors as well as receivers. A P2P network does not increase the total bandwidth available, it just uses the bandwidth better.

In a mesh network, users form new infrastructure by connecting directly (and often through multiple alternate pathes), and the network no longer looks like a tree. A mesh network increases the system's total bandwidth.

Both P2P and mesh networks benefit from "network effects" (i.e., the more users, the better the network), and they are complementary approaches. However, mesh networks have a number of benefits that P2P networks do not, including increasing the resiliency of the network and reducing the control that any ISP can exert over the content distributed on the network and the cost of connection."


Meshworks are different from Ad Hoc Networks

The French article below stresses that meshworks indicate that nodes are connected, usually with their neighbours, while ad hoc means that any node can connect with another temporarily.

Citation:

"On notera qu’une confusion fréquente consiste à assimiler les réseaux “Mesh” et les réseaux “ad hoc”, et les deux avec Wi-Fi. Le concept de réseau “ad hoc” correspond au fait que chaque élément rejoint le réseau de façon immédiate, au besoin (en général, l’élément est identifié par son adresse réseau, reconnue spontanément). Mesh, comme nous l’avons dit, implique simplement que les éléments du réseau sont connectés les uns aux autres et plus exactement, en pratique, à leurs plus proches voisins. Il s’agit d’un type de réseau, pour les infrastructures, équivalent aux réseaux “peer to peer” utilisés au niveau applicatif (pour comparer les différentes topologies réseau existantes : http://en.wikipedia.org/wiki/Network_topology. “Mesh” et “ad hoc” sont donc bien deux notions distinctes." (http://www.internetactu.net/?p=4790)


Mesh Networks are better than Ad Hoc networks and 802.11n

Gurevich:

"The main limitation with the pre-standard mesh implementations is the lack of product interoperability. But if the customer has a standard 802.11 access network, some mesh vendor's products will interoperate with the legacy access points transparently. This is particularly useful in the enterprise and consumer entertainment applications, where mesh offers much promise.

The current crop of 802.11 products work well for traditional applications that focus on Internet-centered activities such as e-mail, Web surfing, downloads, some video streaming and IP telephony. Even multimedia applications are adequately supported with more advanced 802.11n devices.

As wireless networking moves into more heavy-use environments where the amounts of data increase, even 802.11n capability may not be enough. When high-definition multimedia needs to be moved between local devices for rendering, the current wireless hub-and-spoke model will experience limitations.

Wireless meshes offer the solution to this problem. Wireless devices are able to communicate directly without going through a central point (the access point). With mesh topology, traffic can flow via the most optimal path. The Internet access device, which is commonly collocated with the access point, need not become the bottleneck. These networks can even be created without the need for an access point at all, where information will be kept local between the peer devices.

Wireless mesh, as a replacement for the dysfunctional ad hoc mode (one of two ways to currently approach mesh today, the other being wireless distribution system), also will enable personal area networking. Devices such as smartphones can easily mesh with personal media players and video cameras without an dedicated intermediate device such as an access point. If infrastructure is available, these meshed devices will be able to use it to access Internet-based resources as well. This will create opportunities for new types of devices and services.

In industrial environments there has long been a need for wireless mesh solutions. Wireless in general is ideally suited for applications that require easy, inexpensive deployment, resilient and manageable operation, extended range and more uniform coverage. Wireless mesh networks that use off-the-shelf hardware that is on the standards track is ideally suited. The use cases include telematics, sensors, surveillance and security, process controls and robotics.

The ability for meshed devices to offload high-capacity data streams from the access point and distribute the data directly between nodes, and the network infrastructure benefits of mesh topology, signal that the time is right for strong, marketable solutions based on 802.11s. The combination of market needs, emerging trends and the demands for interoperability will finally make meshing a common feature of wireless networks after years of being "right around the corner." (http://www.misweb.com/magarticle.asp?doc_id=26454&rgid=5&listed_months=0)

Hardware and Software Choices

Via [1]:


Possible Hardware Choices


  • Linksys WRT54GL
         o cca $50
         o 802.11b/g
         o no USB
         o removable antenna 
   
  • Linksys WRT54GS
         o $50
         o no USB
         o Flash: 8 MB
         o more powerful than WRT54GL because contains Speedbooster 
   
  • Linksys WRTSL54GS
         o cca $50
         o Flash: 8 MB
         o hard to find
         o similar to WRT54G, but with USB
         o non-removable antenna 
   
  • ASUS WL-520gU
         o cca $45
         o Flash: 4MB
         o 802.11b/g
         o with USB 
   
  • Ubiquiti Nanostation
         o cca $50
         o 802.11b/g
         o supports passive Power Over Ethernet 
   
  • D-link DIR-300


  • Asus Wl5006


Mesh Node Software

  • Open WRT or DD-WRT, Linux distributions for embedded systems
  • 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


More Information

  1. See the Wikipedia article, at http://en.wikipedia.org/wiki/Mesh_networks
  2. A DIY guide to building your own Freifunk-based mesh network
  3. A technically flavored layman's guide to mesh networking
  4. A general overview of wireless networks and a specific high-level overview of mesh networks