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Mesh Networks

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Title: Mesh Network Author: Sri Edupuganti Keywords: Mesh Wireless Network Last modified by: Sri Created Date: 4/16/2005 3:50:09 PM Document presentation format – PowerPoint PPT presentation

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Title: Mesh Networks


1
Mesh Networks
  • Sri Edupuganti

2
The Wireless Paradox Lots of Wires
  • Expensive, difficult to install, and long
    installation time, especially in outdoor
    deployments

3
Traditional vs Ad-hoc Network
Traditional
Mobile Ad-hoc
4
WLAN vs Wireless Mesh
5
Traditional vs Mesh Network
6
Evolution of Mesh
  • It takes a lot of wires to build a wireless
    network
  • If all you have is a hammer every problem looks
    like a nail
  • i.e. APs alone are not the answer
  • The original embodiment of mesh as a wireless
    peer to peer version of the Internet is
    incomplete We moved the mesh one node in.
  • i.e. clients are not part of the mesh
  • Wireless backhaul Mesh is not the same as WiFi
  • Mesh can be the glue to join separate networks
    together

7
What is Wireless Mesh Network?
  • A wireless mesh network is a mesh network created
    through the connection of wireless access points
    installed at each network user's locale.
  • Each network user is also a provider, forwarding
    data to the next node.
  • The networking infrastructure is decentralized
    and simplified because each node need only
    transmit as far as the next node.
  • Wireless mesh networking could allow people
    living in remote areas and small businesses
    operating in rural neighborhoods to connect their
    networks together for affordable Internet
    connections.

8
Mesh topology definition
  • 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."

Full and Partial Mesh Network
9
Functional components of Mesh Networks
10
Access Point and Backhaul Routerof Mesh Network
Like any Wi-Fi access point, the access point in
the mesh router serves the mobile users in the
area. The backhaul side of the device
wirelessly relays the traffic from router to
router until it reaches a gateway that connects
to the Internet or other private network via a
wired or other wireless connection.
11
Network Architecture of Wireless Mesh Network
  • In the wireless mesh network, a node can send and
    receive messages, and it also functions as a
    router and can relay messages for its neighbors.
    Multiple nodes cooperate to relay a message to
    its destination.
  • Through the relaying process, a packet of
    wireless data will find its way to its
    destination, passing through intermediate nodes
    with reliable communication links
  • The mesh topology enhances the overall
    reliability of the network, which is particularly
    important when operating in harsh industrial
    environments.

12
Network Architecture of Wireless Mesh Network
13
Network Architecture of Wireless Mesh Network
14
Working of Mesh Networks
15
Interconnectivity between Mesh and Other Networks
16
Configuration of Mesh Network
  • Networks can be configured in one of several ways
    such as
  • (1) All the BSs, and only the BSs, are
    gateways to the wireless network,
  • (2) none of the BSs are gateways
  • (3) the BSs are gateways (possibly with a
    limited capacity)
  • along with other specific gateways,
  • (4) Every BSs and the MUs it serves are an
    IP-subnet and all these subnets form a single
    IP-network.

17
Mesh networks motivations expectations
  • Until now, mesh networks have most often proposed
    for urban scenarios and municipality networks
  • But there is big potential for rural and remote
    connectivity scenarios

18
Suitability of Mesh Networks in Industrial
Applications

Topology Reliability Adaptability Scalability
Point-to-Point High Low None (2 end points)
Point-to-Multipoint Low Low Moderate (7-30 end points)
Mesh Networks High High Yes (1000s of end points)
19
Advantages of Mesh Networks
20
Advantages of Mesh Networks
  • Decreased need for Internet gateways
  • Collaborative redundant backup technology, which
    insures data security in the event of disk
    failure
  • The ability to configure routes dynamically
  • Lower power requirements, which could potentially
    be met by low-cost or renewable energy sources
  • Increased reliability Each node is connected to
    several other nodes and if one drops out of the
    network, its neighbors simply find another route.
  • Since mesh or multi-hop networks use low power
    transmissions to reach only the nearby nodes
    there is less interference with radio signals
    from other nodes.

21
Why Wireless Mesh Network?
  • Flexible coverage

Reliable routing
22
Mesh Hardware and Software Examples
Hardware
LinkSys WRT54G
Mesh node
4G Access cube
Mesh AP
Software
MeshLinux QuWin
Pebble Zebra/Quagga
OpenWRT
23
Single, Dual, Triple Radio Mesh Routers
  • Mesh routers can employ one, two or three
    radios.
  • A single-radio router shares bandwidth between
    users and the backhaul.
  • If two radios are used, one is dedicated to the
    frontside clients and the other to the backhaul.
  • In three-radio routers, two radios are used for
    the backhaul and can transmit and receive
  • simultaneously over different Wi-Fi channels ,
    such as the systems from BelAir Networks
  • (www.belairnetworks.com) and MeshDynamics
    (www.meshdynamics.com).

24
Infrastructure/Backbone Wireless Mesh Network
25
Hybrid Wireless Mesh Network
26
Mesh routing protocolsElements of mesh routing
A major benefit of wireless mesh networks is
path diversity, which provides many routes to the
central network in case one of the routers fails
or its transmission path is temporarily
blocked. The choice in routing algorithm is
critical, and numerous mesh algorithms have been
used over the years.
  • Node discovery Border discovery
    Link metrics Route calculation IP address
    management Uplink/backhaul management

27
Mesh routing protocols Types
Proactive(Tabledriven) OLSR (Optimized Link
State Routing protocol)OLSREXT,QOLSR TBRPF
(Topology Broadcast based on ReversePath
Forwarding routing protocol) HSLS (Hazy Sighted
Link State routing protocol) MMRP (Mobile Mesh
Routing Protocol), short MobileMesh OSPF (Open
Shortest Path First)
  • Proactive (Tabledriven)
  • Proactive checking of Link state and
    updating of routing tables high complexity and
    CPU load, high performance
  • Reactive (Ondemand)
  • Reacting on detection problems (nonworking
    routes) less demanding on CPU
  • Lines between types are not strict
  • More and mixed types exist

Reactive (Ondemand) AODV
28
Mesh routing protocols
OLSR OLSR is a routing protocol for mobile
ad-hoc networks. The protocol is proactive, table
driven and utilizes a technique called multipoint
relaying (MPR) for message flooding. OLSRD is
meant to be a well structured and well coded
implementation that should be easy to maintain,
expand and port to other platforms. One of the
most promising and stable protocols
  • MMRP(MobileMesh)
  • Mobile Mesh contains 3 separate protocols,
    each addressing a specific function
  • Link Discovery a Simple Hello Protocol
  • Routing Link - State Packet Protocol
  • Border Discovery Enables external tunnels
  • Developed by Mitre (with military
    interest involved)

OSPF Calls for the sending of linkstate
advertisements (LSAs) to all other routers within
the same hierarchical area. Information on
attached interfaces, metrics used, and other
variables included in LSAs. OSPF routers
accumulate linkstate information, use the SPF
algorithm to calculate shortest paths
AODV The Ad hoc On Demand Distance Vector
(AODV) protocol is a routing protocol designed
for mobile ad hoc networks. ...enables dynamic,
self starting, multihop routing between computers.
29
Applications of Mesh Networks
30
Connected and Ad-hoc Mesh Network
31
Security and Encryption in Mesh Networks
32
Message Formats in Mesh Network
33
State diagrams for message passing in Mesh Network
34
Performance Issues in Mesh Network
Throughput Latency Scalability Security
IP distribution
  • Latency obviously has to grow with number of
    hops
  • Effects of latency dependent on application
  • Example VoIP latency can be felt from 170ms
    on, but sometimes walkie talkie with 5 s delay is
    better than nothing

IP distribution in mesh networks is far from
trivial DHCP in private IP ranges is
unproblematic, but what happens when a mesh meets
a neighbour mesh? Ipv6 might solve many issues,
but is not implemented widely yet
  • Ad hoc networks per definition need to talk to
    clients before they know them this imposes an
    inherent security challenge!
  • Vulnerability to Denial of Service attacks

Mesh has not been tested in real life with more
than a few dozen nodes Commercial
implementations (200 nodes? 10,000 nodes?) often
do not share (true) experience and are
therefore hard to evaluate
35
Issues in Mesh Networks
  • Multihop performance degradation
  • Exponential decay, linear decay, or k-asymptotic?
  • Multiple Radios and preventing dynamic frequency
    oscillations in a self aware network
  • Scalability and bridging
  • Most meshes are really small, and joined together
  • IEEE 802 TGs is specifying 32 node maximums!
  • How to manage disjoint but cooperating meshes
  • Multiple loop-free Mesh portals (partially
    solved, but not widely adopted)
  • Mesh Security (solved)
  • Compatibility (intra-mesh, and inter-mesh)

36
Privacy in Mesh Network
37
DEPLOYMENT ISSUES
  • Practical deployment experience shows that simple
    models, while useful, are largely wrong.
  • Metrics for routing need to take into
    consideration expected throughput based on
    network measurement.
  • Self organization is critical, but currently
    lacking.

38
Conclusion
  • Mesh networks can handle many to many
    connections and are capable of dynamically
    updating and optimizing these connections
  • WMNs are a promising technology for next
    generation wireless networking.
  • Many application scenarios are stimulating its
    rapid development.
  • However, to strengthen the market penetration
    and secure the success of WMNs, more research is
    needed.

39
Questions
  • What are functional components of Mesh Network?
  • Ans Routing Functionality(L2 or L3), Access
    point,
  • Gateway Mesh point, Mesh Portal, Base
    station and
  • Mobile station.
  • What are advantages of using Mesh Network?
  • Ans Self forming, Self healing, Self balancing,
    Increased
  • Performance and coverage, Lower
    Infrastructure and Operational
  • costs, and Increased Reliability.
  • What are the issues in Wireless Mesh Networks?
  • Ans Throughput, Latency, Scalability, Security
    and IP distribution

40
References
  • Kevin DeMartino, An Architecture for a Seamless
    Mesh Network, IEEE Communications Magazine
  • http//www.itrainonline.org/itrainonline/mmtk/wire
    less_en/17_Mesh_Networking/17_en_mmtk_wireless_mes
    h-networking_slides.pdf
  • http//www.oreillynet.com/pub/a/wireless/2004/01/2
    2/wirelessmesh.html
  • http//en.wikipedia.org/wiki/Wireless_mesh_network
  • http//en.wikipedia.org/wiki/Mesh_network
  • http//en.wikipedia.org/wiki/Ad_hoc_routing_protoc
    ol_list
  • http//wifinetnews.com/archives/003972.html
  • http//www.sensorsmag.com/articles/0203/38/main.sh
    tml

41
References
  • IAN F. AKYILDIZ, GEORGIA INSTITUTE OF
    TECHNOLOGY,A survey on wireless mesh network
  • Kamlesh Rath, Lalit Kotecha, Howard Persh, Deb
    Ranjan Das, Dat Ton, Scalable Connection
    Oriented Mesh Proposal
  • STEFANO M. FACCIN, MESH WLAN NETWORKSCONCEPT AND
    SYSTEM DESIGN
  • Rainer Baumann, Olga Bondareva, A Macro Mobility
    and Multihoming Notification Protocol for
    Wireless Mesh Networks implementing Mobile IP and
    SHIM6
  • http//www.intel.com/technology/comms/cn02032.htm
  • ieeexplore.ieee.org/iel5/35/32334/01509968.pdf
  • ieeexplore.ieee.org/iel5/2188/19625/00909581.pdf?a
    rnumber909581
  • www.answers.com/topic/wireless-mesh-network
  • www.eng.ucy.ac.cy/toumpis/courses/ECE453/papers/me
    sh2.pdf
  • www.apricot.net/.../120-20Danny20Ng/Apricot202
    00420Wireless20Mesh.pdf
  • Many IEEE papers on Mesh and Wireless Mesh
    Networks.
  • Many documents and links related to Mesh networks
    and Wireless Mesh Networks in google.com and
    ask.com

42
Any Queries?
43
Thank You!!!
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