Title: Mesh Networks
1Mesh Networks
2The Wireless Paradox Lots of Wires
- Expensive, difficult to install, and long
installation time, especially in outdoor
deployments
3Traditional vs Ad-hoc Network
Traditional
Mobile Ad-hoc
4WLAN vs Wireless Mesh
5Traditional vs Mesh Network
6Evolution 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
7What 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.
8Mesh 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
9Functional components of Mesh Networks
10Access 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.
11Network 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.
12Network Architecture of Wireless Mesh Network
13Network Architecture of Wireless Mesh Network
14Working of Mesh Networks
15Interconnectivity between Mesh and Other Networks
16Configuration 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.
17Mesh 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
18Suitability 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)
19Advantages of Mesh Networks
20Advantages 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.
21Why Wireless Mesh Network?
Reliable routing
22Mesh Hardware and Software Examples
Hardware
LinkSys WRT54G
Mesh node
4G Access cube
Mesh AP
Software
MeshLinux QuWin
Pebble Zebra/Quagga
OpenWRT
23Single, 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).
24Infrastructure/Backbone Wireless Mesh Network
25Hybrid Wireless Mesh Network
26Mesh 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
27Mesh 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
28Mesh 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.
29Applications of Mesh Networks
30Connected and Ad-hoc Mesh Network
31Security and Encryption in Mesh Networks
32Message Formats in Mesh Network
33State diagrams for message passing in Mesh Network
34Performance 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
35Issues 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)
36Privacy in Mesh Network
37DEPLOYMENT 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.
38Conclusion
- 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.
39Questions
- 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
40References
- 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
41References
- 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
42Any Queries?
43Thank You!!!