IEEE 802.11s
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IEEE 802.11s is a wireless local area network (WLAN) standard and an
IEEE 802.11 IEEE 802.11 is part of the IEEE 802 set of local area network (LAN) technical standards, and specifies the set of media access control (MAC) and physical layer (PHY) protocols for implementing wireless local area network (WLAN) computer commun ...
amendment for
mesh networking A mesh network is a local area network topology in which the infrastructure nodes (i.e. bridges, switches, and other infrastructure devices) connect directly, dynamically and non-hierarchically to as many other nodes as possible and cooperate wit ...
, defining how wireless devices can interconnect to create a
wireless LAN A wireless LAN (WLAN) is a wireless computer network A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking is a method by which homes, telecommunications networks and bus ...
mesh network, which may be used for relatively fixed (not mobile) topologies and
wireless ad hoc network A wireless ad hoc network (WANET) or mobile ad hoc network (MANET) is a decentralized type of wireless network. The network is ad hoc because it does not rely on a pre-existing infrastructure, such as routers in wired networks or access points ...
s. The IEEE 802.11s task group drew upon volunteers from university and industry to provide specifications and possible design solutions for wireless mesh networking. As a standard, the document was iterated and revised many times prior to finalization. 802.11 are a set of
IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operation ...
standards Standard may refer to: Symbols * Colours, standards and guidons, kinds of military signs * Standard (emblem), a type of a large symbol or emblem used for identification Norms, conventions or requirements * Standard (metrology), an object th ...
that govern wireless networking transmission protocols. They are commonly used today to provide wireless connectivity in the home, office and some commercial establishments. The IEEE 802.11s standard was issued in 2011 and was superseded in 2012 when it became part of the IEEE 802.11 standard that was issued in 2012.


Description

802.11s extends the IEEE 802.11 MAC standard by defining an architecture and protocol that supports both
broadcast Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum ( radio waves), in a one-to-many model. Broadcasting began ...
/
multicast In computer networking, multicast is group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast should not be confused with ...
and
unicast Unicast is data transmission from a single sender (red) to a single receiver (green). Other devices on the network (yellow) do not participate in the communication. In computer networking, unicast is a one-to-one transmission from one point in ...
delivery using "radio-aware metrics over self-configuring multi-hop topologies."


Closely related standards

802.11s inherently depends on one of
802.11a IEEE 802.11a-1999 or 802.11a was an amendment to the IEEE 802.11 wireless local network specifications that defined requirements for an orthogonal frequency-division multiplexing (OFDM) communication system. It was originally designed to support w ...
,
802.11b IEEE 802.11b-1999 or 802.11b is an amendment to the IEEE 802.11 wireless networking specification that extends throughput up to 11 Mbit/s using the same 2.4 GHz band. A related amendment was incorporated into the IEEE 802.11-2007 standard. ...
,
802.11g IEEE 802.11g-2003 or 802.11g is an amendment to the IEEE 802.11 specification that operates in the 2.4 GHz microwave band. The standard has extended throughput to up to 54 Mbit/s using the same 20 MHz bandwidth as 802.11b uses to achieve 11 Mbit/ ...
,
802.11n IEEE 802.11n-2009 or 802.11n is a wireless-networking standard that uses multiple antennas to increase data rates. The Wi-Fi Alliance has also retroactively labelled the technology for the standard as Wi-Fi 4. It standardized support for multiple ...
,
802.11ac IEEE 802.11ac-2013 or 802.11ac is a wireless networking standard in the IEEE 802.11 set of protocols (which is part of the Wi-Fi networking family), providing high-throughput wireless local area networks (WLANs) on the 5 GHz band. The stand ...
, or
802.11ax IEEE 802.11ax, officially marketed by the Wi-Fi Alliance as (2.4 GHz and 5 GHz) and (6 GHz), is an IEEE standard for wireless local-area networks (WLANs) and the successor of 802.11ac. It is also known as ''High Efficiency'' , fo ...
to carry the actual traffic. One or more
routing protocol A routing protocol specifies how routers communicate with each other to distribute information that enables them to select routes between nodes on a computer network. Routers perform the traffic directing functions on the Internet; data packets ...
s suitable to the actual network physical topology are required. 802.11s requires the
Hybrid Wireless Mesh Protocol The Hybrid Wireless Mesh Protocol (HWMP), part of IEEE 802.11s, is a basic routing protocol for a wireless mesh network. It is based on AODV (RFC 3561) and tree-based routing. It relies on a Peer Link Management protocol by which each Mesh Poi ...
, or HWMP to be supported as a default. However, other mesh, ad hoc (
Associativity-Based Routing #REDIRECT Associativity-based routing {{Rcatshell, {{R from move {{R from alternative capitalization ...
,
Zone Routing Protocol Zone Routing Protocol, or ZRP is a hybrid Wireless Networking routing protocol that uses both proactive and reactive routing protocols when sending information over the network. ZRP was designed to speed up delivery and reduce processing overhea ...
, and location based routing) or dynamically link-state routed (
OLSR The Optimized Link State Routing Protocol (OLSR) is an IP routing protocol optimized for mobile ad hoc networks, which can also be used on other wireless ad hoc networks. OLSR is a proactive link-state routing protocol, which uses ''hello'' an ...
,
B.A.T.M.A.N. The Better Approach to Mobile Ad-hoc Networking (B.A.T.M.A.N.) is a routing protocol for Multi-hop routing, multi-hop mobile ad hoc networks which is under development by the German "Freifunk" community and intended to replace the Optimized Link ...
,
OSPF Open Shortest Path First (OSPF) is a routing protocol for Internet Protocol (IP) networks. It uses a link state routing (LSR) algorithm and falls into the group of interior gateway protocols (IGPs), operating within a single autonomous sys ...
) may be supported or even static routing ( WDS). ''See the more detailed description below comparing these routing protocols.'' A mesh often consists of many small nodes. When mobile users or heavy loads are concerned, there will often be a handoff from one base station to another, and not only from 802.11 but from other (
GSM The Global System for Mobile Communications (GSM) is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation ( 2G) digital cellular networks used by mobile devices such as ...
,
Bluetooth Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limi ...
,
PCS A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or techn ...
and other cordless phone) networks. Accordingly,
IEEE 802.21 The IEEE 802.21 refers to Media Independent Handoff (MIH) and is an IEEE standard published in 2008. The standard supports algorithms enabling seamless handover between wired and wireless networks of the same type as well as handover between differe ...
, which specifies this handoff between nodes both obeying 802.11s and otherwise, may be required. This is especially likely if a longer-range lower-bandwidth service is deployed to minimize mesh dead zones, e.g. GSM routing based on
OpenBTS OpenBTS (Open Base Transceiver Station) is a software-based GSM access point, allowing standard GSM-compatible mobile phones to be used as SIP endpoints in Voice over IP (VoIP) networks. OpenBTS is open-source software developed and maintained by ...
. Mesh networking often involves network access by previously unknown parties, especially when a transient visitor population is being served. Thus the accompanying
IEEE 802.11u IEEE 802.11u-2011 is an amendment to the IEEE 802.11-2007 standard to add features that improve interworking with external networks. 802.11 is a family of IEEE technical standards for mobile communication devices such as laptop computers or multi-m ...
standard will be required by most mesh networks to authenticate these users without pre-registration or any prior offline communication. ''Pre-standard
captive portal A captive portal is a web page accessed with a web browser that is displayed to newly connected users of a Wi-Fi or wired network before they are granted broader access to network resources. Captive portals are commonly used to present a landing ...
approaches are also common. See the more detailed description below of mesh security.''


Timeline

802.11s started as a Study Group of IEEE 802.11 in September 2003. It became a Task Group in July 2004. A call for proposals was issued in May 2005, which resulted in the submission of 15 proposals submitted to a vote in July 2005. After a series of eliminations and mergers, the proposals dwindled to two (the "SEE-Mesh" and "Wi-Mesh" proposals), which became a joint proposal in January 2006. This merged proposal was accepted as draft D0.01 after a unanimous confirmation vote in March 2006. The draft evolved through informal comment resolution until it was submitted for a Letter Ballot in November 2006 as Draft D1.00. Draft D2.00 was submitted in March 2008 which failed with only 61% approval. A year was spent clarifying and pruning until Draft D3.00 was created which reached WG approval with 79% in March 2009. In June 2011 the fifth recirculation Sponsor Ballot, on TGs Draft 12.0, was closed. The Draft met with 97.2% approval rate. The 2012 release of the 802.11 specification (802.11-2012) directly incorporates Mesh Routing functionality.


802.11 mesh architecture

An 802.11s
wireless mesh network A wireless mesh network (WMN) is a communications network made up of radio nodes organized in a mesh topology. It can also be a form of wireless ad hoc network.Chai Keong Toh Ad Hoc Mobile Wireless Networks, Prentice Hall Publishers, 2002. A m ...
device is labelled as Mesh Station (mesh STA), or simply an ad hoc node. Mesh STAs form mesh links with one another, over which mesh paths can be established using an ad hoc mobile
routing Routing is the process of selecting a path for traffic in a network or between or across multiple networks. Broadly, routing is performed in many types of networks, including circuit-switched networks, such as the public switched telephone netw ...
protocol. A key aspect of this architecture is the presence of multi-hop wireless links and routing of packets through other nodes towards the destination node.


Routing protocols

''This should be expanded into a treatment of all the compatible routing protocols.'' 802.11s defines a default mandatory routing protocol (
Hybrid Wireless Mesh Protocol The Hybrid Wireless Mesh Protocol (HWMP), part of IEEE 802.11s, is a basic routing protocol for a wireless mesh network. It is based on AODV (RFC 3561) and tree-based routing. It relies on a Peer Link Management protocol by which each Mesh Poi ...
, or HWMP), yet allows vendors to operate using alternate routing protocols. HWMP is inspired by a combination of
AODV Ad hoc On-Demand Distance Vector (AODV) Routing is a routing protocol for mobile ad hoc networks (MANETs) and other wireless ad hoc networks. It was jointly developed in July 2003 in Nokia Research Center, University of California, Santa Barbara an ...
(RFC 3561), which uses on-demand ad hoc routing approach and tree-based routing. Examples of on-demand ad hoc routing are
Dynamic Source Routing Dynamic Source Routing (DSR) is a routing protocol for wireless mesh networks. It is similar to AODV in that it forms a route on-demand when a transmitting node requests one. However, it uses source routing instead of relying on the routing tab ...
and
Associativity-Based Routing #REDIRECT Associativity-based routing {{Rcatshell, {{R from move {{R from alternative capitalization ...
. AODV route discovery and localized route repair approaches are identical to Associativity-based Routing. Prior work has discussed and compared these various routing protocols in detail. Mesh STAs are individual devices using mesh services to communicate with other devices in the network. They can also collocate with 802.11 Access Points (APs) and provide access to the mesh network to 802.11 stations (STAs), which have broad market availability. Also, mesh STAs can collocate with an 802.11 portal that implements the role of a gateway and provides access to one or more non-802.11 networks. In both cases, 802.11s provides a proxy mechanism to provide addressing support for non-mesh 802 devices, allowing for end-points to be cognizant of external addresses. 802.11s also includes mechanisms to provide deterministic network access, a framework for
congestion control Network congestion in data networking and queueing theory is the reduced quality of service that occurs when a network node or link is carrying more data than it can handle. Typical effects include queueing delay, packet loss or the blocking of ...
and power save.


Mesh security

There are no defined roles in a mesh — no clients and servers, no initiators and responders. Security protocols used in a mesh must, therefore, be true peer-to-peer protocols where either side can initiate to the other or both sides can initiate simultaneously.


Peer authentication methods

Between peers, 802.11s defines the secure password-based authentication and key establishment protocol
Simultaneous Authentication of Equals In cryptography, Simultaneous Authentication of Equals (SAE) is a password-based authentication and password-authenticated key agreement method. Authentication SAE is a variant of the Dragonfly Key Exchange defined in , based on Diffie–Hellma ...
(SAE). SAE is based on
Diffie–Hellman key exchange Diffie–Hellman key exchangeSynonyms of Diffie–Hellman key exchange include: * Diffie–Hellman–Merkle key exchange * Diffie–Hellman key agreement * Diffie–Hellman key establishment * Diffie–Hellman key negotiation * Exponential key exc ...
using finite cyclic groups which can be a
primary cyclic group In mathematics, a primary cyclic group is a group that is both a cyclic group and a ''p''-primary group for some prime number ''p''. That is, it is a cyclic group of order ''p'', C, for some prime number ''p'', and natural number ''m''. Every f ...
or an
elliptic curve In mathematics, an elliptic curve is a smooth, projective, algebraic curve of genus one, on which there is a specified point . An elliptic curve is defined over a field and describes points in , the Cartesian product of with itself. If ...
. The problem with a Diffie–Hellman key exchange is that it does not have an authentication mechanism. So the resulting key is influenced by a
pre-shared key In cryptography, a pre-shared key (PSK) is a shared secret which was previously shared between the two parties using some secure channel before it needs to be used. Key To build a key from shared secret, the key derivation function is typically us ...
and the
MAC address A media access control address (MAC address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking techno ...
es of both peers to solve the authentication problem. When peers discover each other (and security is enabled) they take part in an SAE exchange. If SAE completes successfully, each peer knows the other party possesses the mesh password and, as a by-product of the SAE exchange, the two peers establish a cryptographically strong key. This key is used with the "Authenticated Mesh Peering Exchange" (AMPE) to establish a secure peering and derive a session key to protect mesh traffic, including routing traffic.


Implementations

The IEEE 802.11s amendment is supported by many products such as open80211s, OLPC. In open80211s smaller meshes of under 32 nodes are supported. Some of the projects were based on earlier (draft) versions. * A reference implementation of the 802.11s draft is available as part of the mac80211 layer in the
Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ope ...
, starting with version 2.6.26. The Linux community, with its many diverse distributions, provides a heterogenous testing ground for protocols like
Hybrid Wireless Mesh Protocol The Hybrid Wireless Mesh Protocol (HWMP), part of IEEE 802.11s, is a basic routing protocol for a wireless mesh network. It is based on AODV (RFC 3561) and tree-based routing. It relies on a Peer Link Management protocol by which each Mesh Poi ...
.
OpenWrt OpenWrt (from ''open wireless router'') is an open-source project for embedded operating systems based on Linux, primarily used on embedded devices to route network traffic. The main components are Linux, util-linux, musl, and BusyBox. All com ...
, a Linux distribution for routers, supports mesh networking. * In
FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...
, the 802.11s draft is supported starting with FreeBSD 8.0. * The Google Wifi router uses the 802.11s mesh networking protocol. * The MeshPoint.One router uses 802.11s mesh networking protocol.


See also

*
Wireless mesh network A wireless mesh network (WMN) is a communications network made up of radio nodes organized in a mesh topology. It can also be a form of wireless ad hoc network.Chai Keong Toh Ad Hoc Mobile Wireless Networks, Prentice Hall Publishers, 2002. A m ...
*
Wireless ad hoc network A wireless ad hoc network (WANET) or mobile ad hoc network (MANET) is a decentralized type of wireless network. The network is ad hoc because it does not rely on a pre-existing infrastructure, such as routers in wired networks or access points ...
s *
List of ad hoc routing protocols An ad hoc routing protocol is a convention, or standard, that controls how nodes decide which way to route packets between computing devices in a mobile ad hoc network. In ad hoc networks, nodes are not familiar with the topology of their network ...
*
Mobile ad hoc network A wireless ad hoc network (WANET) or mobile ad hoc network (MANET) is a decentralized type of wireless network. The network is ad hoc because it does not rely on a pre-existing infrastructure, such as routers in wired networks or access points ...


References


External links


Status of 802.11s

Open80211s.org

Wifi/Mesh - FreeBSD Wiki
{{DEFAULTSORT:Ieee 802.11s S