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Mesh Network Design and Implementation using off-the-shelf Wireless Routers and Linux

SBRC 2005 RNP Annual Workshop Brazil. Mesh Network Design and Implementation using off-the-shelf Wireless Routers and Linux. Nikolaos Tsarmpopoulos Department of Computer and Communications Engineering, University of Thessaly, Greece. Dedicated to Dr. Ketsiri Kueseng

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Mesh Network Design and Implementation using off-the-shelf Wireless Routers and Linux

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  1. SBRC 2005RNP Annual WorkshopBrazil Mesh Network Design and Implementation using off-the-shelf Wireless Routers and Linux Nikolaos Tsarmpopoulos Department of Computer and Communications Engineering, University of Thessaly, Greece

  2. Dedicated to Dr. Ketsiri Kueseng Lecturer in Materials Science Walailak University, Thailand Missing since 26th December 2004 RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  3. About the research group • University of Thessaly: • Department of Computer and Communications Engineering http://inf.uth.gr/ • Distributed Computing and Software Engineering Group • Topics of Research: • Pervasive computing • Mobile computing • Distributed systems • Peer-to-Peer systems • People involved in “VMesh” project: • Dr. Nikolaos Tsarmpopoulos • Mr. Ioannis Kalavros • Dr. Spyros Lalis RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  4. Purposes of VMesh Project • Design a wireless mesh network architecture supporting all types of IP-enabled devices. • Design and implement a wireless router for building city-wide mesh networks. • Reuse low-cost, off-the-shelf wireless routers for the purpose of building mesh networks. • Build a testbed network. RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  5. Testbed Networks • Can be used for the purposes of: • Experimentation on new protocols and technologies. • Evaluation in real world environments. • Research and Development (R&D). • Education (hands-on experience). • Building communities. • Supporting emergency services: • police, fire brigade, ambulance, rescue workers RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  6. “VMesh” Project Plan • Evaluate the social and economic factors in building community networks. • Evaluate the technological factors in building wireless testbed networks. • Develop the required technology. • Deploy a prototype testbed (proof of concept). • Let the users deploy the network in large scale. • Exploit the potential of the testbed. • Identify key areas for future research. RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  7. Challenges • Cost • Hardware • Software • Deployment • Maintenance • Programmable/expandable platform • Open Source • Standards-based • Configuration • Ease of configuration • License • Radio Spectrum • Access to tall buildings • Social factors (!!!) • Deployment • Ease of deployment • Required expertise RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  8. Challenges • Cost Proposed Solutions • Hardware  Off-the-shelf / Embedded • Software  GPL-licensed • Deployment  By end users • Maintenance  By end users • Programmable/expandable platform • Open Source  Linux • Standards-based  IEEE 802.11b/g • Configuration • Ease of configuration  Statically assigned • License • Radio Spectrum  ISM Band (2.4GHz) • Access to tall buildings  By end users • Social factors (!!!)  By end users (!!!) • Deployment • Ease of deployment  Use of Omni antennas • Required expertise  None! RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  9. Design Requirements • Automatically adapt to changes in topology. • Provide the means for seamless connectivity of user terminals (without requiring additional software). • Support multiple Internet gateways. • Support authenticated, secure access to selected services. • Support Wi-Fi compliant products. RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  10. Design Decisions • Use Optimized Link State Routing (OLSR). • Use of Proxy ARP function between the user terminal and the router. • Use semi-automated IP address assignment. • Combine wireless routers with access points for supporting typical Wi-Fi devices (PDAs, laptops). • Use VPN technology for controlled access to selected network resources and services. RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  11. 1. OLSR • Characteristics: • Table driven (easy to implement and port). • Proactive (no initial delays for route calculation). • Scalable: Suited for large and dense networks with low-mobility rate. • shelf-healing (routes are periodically and dynamically recomputed). RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  12. 2. Proxy ARP Functionality: • The router responds to all ARP requests submitted by the user terminal (on the Ethernet interface) with its own MAC Address. • The data packets transmitted by the user terminal have the correct destination IP address (layer 3), and the MAC address of the router (layer 2). • The router forwards the data packets on behalf of the user terminal. User Terminal Router MANET Who has <IP address> ? <My MAC> has <IP Address>. ARP resolution for next-hop router Send data packet to <IP address> Send data packet to <IP address> RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  13. 3. IP Address Assignment • Every wireless MANET node is: • Statically assigned a unique IP address on the Wireless Interface (MANET) • On our network: 10.151.0.0/16 • Statically assigned a unique IP subnet for non-OLSR user terminals, connected to its LAN segment. • The 1st usable address of the subnet is assigned to the router LAN interface. The remaining are assigned to user terminals using DHCP. • One our network (e.g.): 10.152.0.0/27 RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  14. ROUTER IP SETTINGS WLAN InterfaceIP Address: 10.151.0.6Subnet Mask: 255.255.0.0 LAN InterfaceIP Address: 10.152.0.161DHCP From: 10.152.0.162DHCP To: 10.152.0.190Subnet Mask: 255.255.255.224 WAN InterfaceIP Address: DHCP assignedSubnet Mask: DHCP assignedDefault Gateway: DHCP assigned 10.151.0.5 10.151.0.4 10.151.0.6 10.151.0.2 10.151.0.3 Each node is assigned an IP address on the subnet of the Ad Hoc network.On our network: 10.151.0.0/16 R R R R R Router IP Configuration Example RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  15. MANET Router Access Point Mobile users (non-OLSR) R R R R 4. Ad Hoc + Infrastructure • Routers form a mesh network using OLSR protocol. • Wi-Fi Access Points let mobile users access a non-OLSR segment (subnet) of the network attached to the Ethernet interface of the router. RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  16. MANET VPN Server Protected network Router Access Point Mobile users (non-OLSR) R R R R 5. VPN technology • Point-to-Point Tunnelling Protocol provides user authentication encryption functions. RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  17. Wi-Fi compliant hotspot 3 2 1 OLSR-capable mobile terminals Wireless LAN MANET Home / Office LAN R R R R R R R R R Wireless Connection (Infrastructure mode) Ethernet Connection Wireless Connection (Ad Hoc mode) Ad Hoc Router Usage Scenarios 1. MANET – LAN connectivity, 2. MANET – Wi-Fi connectivity, 3. Mobility (OLSR) RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  18. Wireless Node Basic Requirements • 802.11b/g standards based • Network interfaces: • Wireless network interface (802.11b/g) • For connecting to the MANET (backbone network) • Ethernet network interface (LAN) • For connecting personal computers and wireless access points • Ethernet network interface (Ethernet) • Internet broadband connection • Linux-based firmware RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  19. ((( ))) 802.11g Radio OLSRIP Forwarding DHCP ServerProxy ARPIP Forwarding Switched Ports (LAN) DHCP ClientIP Forwarding Wi-FiAccess Point WAN Port (public Internet) Optional external connection Optional external connection Wireless Router Architecture RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  20. IP Configuration made easy (part1) • We need to configure 3 interfaces: • Wireless interface (mesh network) • LAN interface (Ethernet) • WAN interface (connection to Internet) • 2 step process: • Each node is statically assigned a unique identifier NodeID (integer value starting from zero). • Each node derives all IP configuration settings from its identifier. RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  21. IP configuration made easy (part2) • Wireless interface: • echo "10.151."$(((1+$1)/256))"."$(((1+$1)%256)) • Netmask: 255.255.0.0 • $1 contains the node identifier (NodeID) • LAN interface: • Every LAN segment on a VMesh wireless router is assigned an IP subnet of 32 addresses. • LAN interface IP Address: echo "10."$((152+($1/2048)))".“ $(((($1*32)%65536)/256))"."$((($1*32)%256+1)) • Netmask: 255.255.255.224 RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  22. IP configuration made easy (part3) • DHCP Server on LAN interface • “DHCP From” Address: echo "10."$((152+($1/2048)))"."$(((($1*32)%65536)/256))"."$((($1*32)%256+2)) • “DHCP To” Address: echo "10."$((152+($1/2048)))"."$(((($1*32)%65536)/256))"."$((($1*32)%256+30)) Netmask: 255.255.255.224 • WAN interface: • DHCP assigned IP settings RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  23. Enabling Technologies • Wireless Router Application Platform (PC Engines WRAP®) • Low-cost 802.11g Broadcom wireless router platform (Linksys® WRT54G/GS®) • OpenWRT Linux(http://www.openwrt.org) • A. Tønnesen’s OLSR implementation (http://www.olsr.org) RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  24. WRAP® Platform (PC Engines GmbH) • National Semiconductors Geode SC1100 (233 MHz) • 64MBytes RAM • 1 Ethernet interface (100Mbps) • 1-2 Wireless interfaces (miniPCI Cards) • 1 RS232 interface (we can use it for sensors) • Slot for removable CompactFlash (IDE Drive) • Thermal Zone detector • Watchdog timer • Power over Ethernet (802.3af) • Low Power Consumption (10 Watt) RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  25. Linksys® Hardware • WRT54G (version 2.0): • Broadcom MIPS BCM4702KPB, 125MHz, 4MB Flash, 16MB RAM, 5 port 10/100 Ethernet switch, 802.11g Broadcom wireless chipset. • WRT54GS (version 1.0): • Broadcom MIPS BCM4712KPB, 200Mhz, 8MB Flash, 32MB RAM, 5 port 10/100 Ethernet switch, 802.11g Broadcom wireless chipset. • New hardware versions have become available and require updated firmware (drivers for ethernet chipset) RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  26. OpenWRT-based firmware • We expanded OpenWRT to support: • OLSR implementation (by A. Tønnesen, Th. Lopatic) • Auto-configuration scripts for: • Network interfaces, DHCP, OLSR, IP Forwarding, Proxy ARP • Scripts for collecting performance measurements • Scripts for posting measurements via HTTP to an SQL database • User-accessible troubleshooting web Interface for: • Displaying other 802.11 Wireless Networks • Displaying 1-hop neighbour nodes • Displaying LAN, WLAN, WAN ports configuration settings RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  27. Deployment WRAP Linux router in a water-proof case (dual WLAN) Linksys WRT54GS OpenWRT router board Roof-top installation of Linksys router with 15dBi omni directional antenna RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  28. Routing Table RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  29. Troubleshooting Web Interface RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  30. Experiences • Router is easily configured in a timely manner • Firmware installation + configuration: 5 minutes • Node deployment is relatively easy • Cabling, packaging, mounting: 2 hours • Network stability: • Links between nodes with distance up to 300m are stable. • Stability is improved as new nodes are added in between other nodes. • Other factors: antenna, line-of-sight, interference, weather, environment. • High-gain antennas used: 8dBi (up to 300m) • Bandwidth: • Transfer rates up to 800Kbytes/second (DC++ file transfers during network idle times) • TCP Performance: • TCP exhibits poor performance over multi-hop connections if one or more links are unstable. This behaviour affects the performance of VPN connections. RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  31. Firmware Upgrades • There are two methods for upgrading firmware: • Partial updates • Are performed by replacing existing files with newer ones. • Tools: BASH (for shell scripts), scp (Secure FTP), wget (HTTP), ssh (Secure Shell) • Advantage: Can be performed remotely, over an Ethernet (LAN) or wireless connection. • Firmware replacement • Disadvantage: It currently requires physical access to the device (access to the hardware reset button). • In newer versions of the firmware, this should be fixed, allowing remote firmware replacement. RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  32. Contributions and Achievements • Contributions: • A complete network architecture for wireless network testbeds • Implementations for two different hardware platforms • Technical Achievements: • Compiled firmware for easily configurable, easily deployable, off-the-shelf wireless routers • Combined various different network technologies to achieve seamless interoperability with mobile user terminals RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  33. Research Topics (1/2) • Fast, Efficient Mobility in MANETs • Non-OLSR aware, Wi-Fi mobile devices may roam between Access Points attached to different wireless routers. • Workaround: The client refreshes his IP settings (using DHCP client) • Secure, Efficient Network Management in Ad Hoc Networks • Automated firmware upgrades on the routers • Updating router settings RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  34. Research Topics (2/2) • Dynamic IP configuration for: • Ad Hoc nodes • Improve TCP performance • Investigate alternative protocols to TCP, for use over the wireless network • Design and implement on the routers a “proxy” service. • Virtual Networks • Use a MANET to build the infrastructure for supporting multiple virtual wireless networks (managed/controlled independently by ISPs) • Wi-Fi compliant Access Mechanisms on Wireless Routers. Eliminate the need for additional hardware (Access Points). • Perimeter-based AAA • Secure mesh network backbone RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly

  35. Thank you Project’s Web Site:http://vmesh.inf.uth.gr/

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