CS-435 spring semester Network Technology & Programming Laboratory. Stefanos Papadakis & Manolis Spanakis

Transcription

1 CS-435 spring semester 2014 Network Technology & Programming Laboratory University of Crete Computer Science Department Stefanos Papadakis & Manolis Spanakis

2 CS-435 Lecture preview Ad-Hoc Networks Mesh Networking

3 The Simpson's Ad-Hoc? vs. Mesh? I can hear u, Lisa.

4 Mobile Ad Hoc Networks May need to traverse multiple links to reach a destination

5 Mobile Ad Hoc Networks (MANET) Mobility causes route changes

6 Why Ad Hoc Networks? Ease and Speed in deployment Decreased dependence on infrastructure Only possible solution to interconnect a group of nodes Many Commercial Products available today

7 Introduction In the past the Ad hoc Networking paradigm absorbed a lot of research effort. Most of the work is focused on isolated military or specialized civilian application multi-hop ad hoc networks. Turning ad-hoc networks into a commodity takes a few changes Make multi-hop flexible low cost last mile-extensions of wired infrastructure: Turn them into MESH NETWORKS!

8 MANET Applications Body Area Networking body sensors network, Personal area Networking cell phone, laptop, ear phone, wrist watch Emergency operations search-and-rescue (earthquakes, boats, airplanes ) policing and fire fighting Military environments soldiers, tanks, planes, battlefield Civilian environments taxi cab network meeting rooms sports stadiums boats, small aircraft

9 Variations Traffic characteristics may differ in different ad hoc networks bit rate, reliability requirements, unicast, multicast, host-based addressing, content-based addressing, capability-based addressing Adhoc networks may co-exist and co-operate with infrastructure-based networks Mobility characteristics may be different speed, direction of movement, pattern of movement Symmetric vs. Asymmetric nodes capabilities and responsibilities

10 Issues in Mobile Ad-hoc Networks Limited wireless transmission range Broadcast nature of the wireless medium Hidden terminal problem Packet losses due to transmission errors Mobility-induced route changes Mobility-induced packet losses Battery constraints Potentially frequent network partitions Ease of snooping on wireless transmissions (security hazard)

11 What s unique about a Moving nodes MANET? ever changing topology Wireless links various and volatile link quality Pervasive (cheap) devices Security Power constraints Confidentiality, other attacks

12 Ad-hoc & p2p a Comparison P2P is based on an IP network Ad-hoc is based on a mobile radio network Mobile Ad-hoc and Peer-to-Peer Networks hold many similarities concerning their routing algorithms and network management principles Both have to provide networking functionalities in a completely unmanaged and decentralized environment ie. To determine how queries (packets) are guided through the network

13 Ad-hoc & p2p a Comparison

14 Ad-hoc & p2p - Differences

15 Ad-hoc & p2p - Similarities

16 Is the ad-hoc paradigm failed? An ad-hoc network is a collection of mobile nodes that connect over the wireless medium without the need of any pre-deployed infrastructure. Nodes in a MANET can dynamically self-organize into temporary and arbitrary and network topologies No pre-existing infrastructure required: Many supporting application scenarios: Disaster Recovery Areas Battlefields

17 Is the ad-hoc paradigm failed? Key Research drivers Bluetooth and WiFi mass market deployment ZigBee IETF MANET WG standardizations Main problem: Users want: affordable devices Internet access Is high quality connectivity during mobility such an important issue?

18 Making ad-hoc networks a commodity Pass down research from the MANET field to a more marketviable networking paradigm. Relax the main constraint of MANETS: Accept the existence of wired infrastructure Wireless Mesh Networks (WMNs) are build by interconnecting internet egress points with end-user devices can act as terminals and as routers. Community Networks being the earliest form of Meshes, relaxed a second MANET feature: Mesh nodes are practically stationary

19 Wireless Mesh Networks Wireless Mesh Networks (WMN) are the networks in which each node can communicate directly with one or more peer nodes. Different from traditional wireless networks (e.g WLANs) requiring centralized access points to mediate the wireless connection. Each node operates not only as a host but also as a router, forwarding packets on behalf of other nodes that may not be within direct wireless transmission range of their destinations. It is dynamically self-organized and self-configured, nodes can automatically establishing and maintaining mesh connectivity among nodes

20 Network Architecture WMNs consist of two types of nodes: Mesh Routers and Mesh Clients Mesh router Additional routing functions to support mesh networking. Multiple wireless interfaces with same or different wireless access technologies. The gateway/bridge functionalities enable the integration of WMNs with existing wireless networks(cellular, sensornet, Wi-Fi, WiMAX). Mesh Clients Conventional nodes (e.g., desktops, laptops, PDAs, PocketPCs, phones, etc.) equipped with wireless network interface cards (NICs), and can connect directly to wireless mesh routers. Customers without wireless NICs can access WMNs by connecting to wireless mesh routers through, e.g., Ethernet

21 WMN Architecture Classifications Infrastructure Meshing Mesh routers form an mesh infrastructure among themselves. Provides backbone for clients and enables integration of WMNs with existing wireless networks and Internet through gateway/bridge functionalities. Clients connect to mesh router with wireless link or Ethernet Client Mesh Networking Client nodes constitute peer-to-peer network, and perform routing and configuration functionalities as well as provide end-user applications to customers, mesh routers are not required. Multi-hop routing. Client nodes have to perform additional functions such as routing and self-configuration. Hybrid Mesh Networking A combination of infrastructure and client meshing. Infrastructure provides connectivity to other networks such as the Internet, Wi-Fi, WiMAX, cellular, and sensor networks; Mesh clients can access the network through mesh routers as well as directly meshing with other mesh clients. The routing capabilities of clients provide better connectivity and coverage

22 WMNs Characteristics Multi-hop wireless networks Support for Ad Hoc networking, and capability of selfforming, self-healing, and self-organization Mobility dependence on the type of mesh nodes Multiple types of network access Dependence of power-consumption constraints on the type of mesh nodes Compatibility and interoperability with existing wireless networks

23 Protocol Design Physical Layer Mac Layer Network Layer Transport Layer Application Layer Network Management Security

24 A Wireless Mobile Ad hoc Network A 10-node MANET at time t0

25 A Wireless Mobile Ad hoc Network A 10-node MANET at time t1

26 How does this change look like? A wireless mesh network of 3 tiers

27 Ad-hoc WMN, what is different? The WMN concept is similar to ad-hoc networks concept but has four important differences: 1. (practically) fixed nodes => Topology changes are infrequent Addition of nodes Node failure or maintenance 2. Traffic distribution is skewed (to/from the wired network) 3. Traffic characteristics aggregated from large numbers of flows => network optimization based on profiling 4. Reactive discovery of multi-hop paths is not efficient for an effective backbone and not fit under (1).

28 Mesh Networking - Overview Node Types Wireless routers Gateways Link Types Intra-mesh wireless links Stationary client access Printers, servers Mobile client access Mobile clients Stationary clients Internet access links

29 How it Works User-Internet Data Flows In most applications the main data flows User-User Data Flows In most applications a small percentage of data flows

30 Taxonomy (example) Wireless Networking Single Hop Multi-hop Infrastructure-based (hub&spoke) Infrastructure-less (ad-hoc) Infrastructure-based (Hybrid) Infrastructure-less (MANET) Bluetooth Cellular Networks Wireless Sensor Networks Wireless Mesh Networks Car-to-car Networks (VANETs)

31 Mesh vs. Ad-Hoc Networks Ad-Hoc Networks Multi-hop Nodes are wireless, possibly mobile Do not rely on infrastructure Most traffic is user-touser Wireless Mesh Networks Multi-hop Nodes are wireless, some mobile, some fixed It relies on infrastructure Most traffic is user-togateway

32 Mesh vs. Sensor Networks Wireless Sensor Networks Bandwidth is limited (tens of kbps) In most applications, fixed nodes Energy efficiency is an issue Resource constrained Most traffic is user-togateway Wireless Mesh Networks Bandwidth is generous (>1Mbps) Some nodes mobile, some fixed Normally not energy limited Resources are not an issue Most traffic is user-togateway

33 Application domain Broadband Internet Access Extend WLAN Coverage Mobile Internet Access Direct competition with cellular systems Emergency Response Layer 2 Connectivity entire wireless mesh cloud becomes one (giant) Ethernet switch Military Communications Community Networks Other: Remote monitoring and control Public transportation Internet access Multimedia home networking Internet

34 Research Topics Physical Layer Smart Antennas Transmission Power Control MAC Layer Multiple Channels Network Layer Routing Fairness and QoS Transport Layer Provisioning Security Network Management Geo-location

35 QoS requirements Physical Layer Robust modulation Link adaptation MAC Layer Offer priorities Offer guarantees (bandwidth, delay) Network Layer Select good routes Offer priorities Reserve resources (for guarantees) Transport Attempt end-to-end recovery when possible Application Negotiate end-to-end and with lower layers Adapt to changes in QoS

36 A key research decision that made a big difference Test-beds were used in WMN research from the start. MIT Roofnet ( Proof of existence of good enough solution for civilian applications has stimulated the users interest to adopt this technology. Two main solutions classes: 1. off-the-shelf => community networks Roofnet AWMN FORTH BAWUG Seattle Wireless 2. proprietary => MeshNetworks, Tropos Networks, Radiant

37 Companies State of the art Aerial Broadband BelAir Networks Firetide Intel Kiyon LamTech (ex. Radiant) Locust World Mesh Dynamics Microsoft Motorola (ex. Mesh Networks) Nokia Rooftop Nortel Networks Packet Hop Ricochet Networks SkyPilot Networks Strix Systems Telabria Tropos Networks

38 University Testbeds Georgia Tech - BWN-Mesh MIT - Roofnet Rutgers WinLab Orbit SUNY Stonybrook Hyacinth University of Utah Emulab FORTH (eu - MESH)

39 Georgia Institute of Technology 15 IEEE b/g nodes Flexible configuration and topology Can evaluate routing and transport protocols for WMNs. Integrated with the existing wireless sensor network testbed BWN-Mesh Source:

40 MIT Roofnet Experimental testbed More than 40 nodes at the present Real users (volunteers) Focus on link layer measurements and routing protocols Open source software runs on Intersil Prism 2.5 or Atheros AR521X based hardware Source:

41 Rutgers Winlab ORBIT Collaborative NSF project (Rutgers, Columbia, Princeton, Lucent Bell Labs, Thomson and IBM Research) Start date: September 2003 Emulator/field trial wireless system 400 nodes radio grid supporting x Software downloaded for MAC, routing, etc. Outdoor field trial Source:

42 SUNY Stonybrook Hyacinth Multichannel test-bed based on stock PCs with two a NICs. Research focus on: interface channel assignment routing protocol Source:

43 University of Utah Emulab Three experimental environments Simulated and Emulated hundreds of PCs (168 PCs in racks) Several with wireless NICs ( a/b/g) wide-area network nodes geographically distributed across approximately 30 sites Smaller brothers at U. of Kentucky Georgia Tech Source:

44 metropolitan mesh FORTH s metropolitan mesh network testbed network testbed 14 nodes: 6 multi-radio / PC-based independent management network km links 60sq.km. coverage

45 Extended testing capabilities cross layer data acquisition parallel processing remote management remote & local storage high computing power 4+1 wireless interfaces per node UPS & remote power management Linux operating system

46 Features - Advantages - Flexibility - Adaptability real life environment city wide deployment high density population coverage over 9 years of experience off-the-self hardware highly customizable & expandable multiple Internet gateways service-driven network virtualization mobile social networking location based services emergency services rapid deployment scenarios ubiquitous wireless access future technologies proof

47 Standards & Committees IEEE standards groups actively working to define specifications for wireless mesh networking techniques Special groups established to define the requirements for mesh networking in WPANs, WLANs, and WMANs. The following standards amendments are considering WMNs: (bluetooth - WPAN) s (wi-fi - WLAN) a (wi-max - WMAN) Also (wireless mobile broadband access -WMBA) is to support the Mesh Networking paradigm from the first spec. On 12 June 2008, the IEEE approved the new standard

48 The s ideas The group had set up the TG s to discuss proposals for a specs amendment in the 2nd quarter of 05 and reach a final document no sooner than And still is at the drafting stage Scope of the Project: An IEEE Extended Service Set (ESS) Mesh is a collection of APs interconnected with wireless links that enable automatic topology learning and dynamic path configuration. The proposed amendment shall be an extension to the IEEE MAC. The amendment will define an architecture and protocol for providing an IEEE ESS Mesh using the IEEE MAC to create an IEEE Wireless Distribution System that supports both broadcast/multicast and unicast delivery at the MAC layer using radio-aware metrics over selfconfiguring multi-hop topologies. An ESS Mesh is functionally equivalent to a wired ESS, with respect to the STAs relationship with the BSS and ESS.

49 The s ideas The amendment shall: Enable interoperable formation and operation of an ESS Mesh extensible to allow for alternative path selection metrics and/or protocols based on application requirements. target configuration of up to 32 devices participating as AP forwarders in the ESS Mesh. Larger configurations may also be contemplated by the standard. The architecture defined by the amendment shall allow an ESS Mesh to interface with higher layers and to connect with other networks using higher layer protocols. Utilize IEEE i security mechanisms, or an extension thereof, for the purpose of securing an ESS Mesh in which all of the APs are controlled by a single logical administrative entity for security. Allow the use of one or more IEEE radios on each AP in the ESS Mesh.

50 802.11s timeline s started as a Study Group of IEEE in September Became a Task Group in July A call for proposals was issued in May 2005, which resulted in the submission of 15 proposals submitted to a vote in July 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 This merged proposal was accepted as draft D0.01 after a unanimous confirmation vote in March 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 The Task Groups stated goal for the May meeting is to start resolving comments from its new Letter Ballot

51 IEEE Bluetooth Low data rate (1Mbps bitrate) BAN/PAN technology Targets wire replacement Has provisions for multi-hop scatter-nets Not a popular wireless mesh network platform due to: the low bandwidth and limited hardware support for scatter-nets.

52 IEEE Zigbee Lower data rate BAN/PAN (250,40,20kbps) Multi-months years lifetime on small batteries Supports mesh topology one coordinator is responsible for setting up the network Characteristics suitable for wireless sensor networks rather than wireless mesh networks

53 IEEE Mesh Topology Capability in (WPANs). Standard applicable to all other WPANs Mesh networks have the capability to provide: Extension of network coverage without increasing transmit power or receive sensitivity Enhanced reliability via route redundancy Easier network configuration Better device battery life due to fewer retransmissions

54 The a is a point to multipoint first-mile/last-mile WMAN connection standard data rate up to 30miles great for gateway to internet links A base station serves a number of subscriber stations BS uses a broadcast channel to transmit to all SSs approved in 2001 (10-66GHz operation TDMA, TDD&FDD) a approved in Jan (2-11 GHz operation added -ODFM) The extensions specifies user-user links using: either centralized schedules, or distributed schedules. Already obsolete and part of the doc Stations may have direct links to each other - control can be distributed. WiMax forum formed later in 2003 (just like the Wi-Fi forum) to promote IEEE standards for interoperability) Certifications began as late as 2006

55 More references. Roofnet Seattle Wireless Locust World Kingsbride Link Mesh Networks Inc FireTide Inc. Strix Networks Inc Telabria Inc Tropos Inc Cowave Inc