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 SBRC 2005 RNP Annual Workshop Brazil

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

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

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

RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly “VMesh” Project Plan 1.Evaluate the social and economic factors in building community networks. 2.Evaluate the technological factors in building wireless testbed networks. 3.Develop the required technology. 4.Deploy a prototype testbed (proof of concept). 5.Let the users deploy the network in large scale. 6.Exploit the potential of the testbed. 7.Identify key areas for future research.

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

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

RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly 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 Design Decisions 1.Use Optimized Link State Routing (OLSR). 2.Use of Proxy ARP function between the user terminal and the router. 3.Use semi-automated IP address assignment. 4.Combine wireless routers with access points for supporting typical Wi-Fi devices (PDAs, laptops). 5.Use VPN technology for controlled access to selected network resources and services.

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

RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly 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 ? has. Send data packet to ARP resolution for next-hop router

RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly 3. IP Address Assignment Every wireless MANET node is: Statically assigned a unique IP address on the Wireless Interface (MANET) Statically assigned a unique IP address on the Wireless Interface (MANET) On our network: /16 Statically assigned a unique IP subnet for non-OLSR user terminals, connected to its LAN segment. Statically assigned a unique IP subnet for non-OLSR user terminals, connected to its LAN segment. The 1 st 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.): /27

RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly Router IP Configuration Example ROUTER IP SETTINGS WLAN Interface IP Address: Subnet Mask: LAN Interface IP Address: DHCP From: DHCP To: Subnet Mask: WAN Interface IP Address: DHCP assigned Subnet Mask: DHCP assigned Default Gateway:DHCP assigned Each node is assigned an IP address on the subnet of the Ad Hoc network. On our network: /16

RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly 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. MANET Router Access Point Mobile users (non-OLSR)

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

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

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

RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly Wireless Router Architecture g Radio OLSR IP Forwarding DHCP Server Proxy ARP IP Forwarding Switched Ports (LAN) DHCP Client IP Forwarding WAN Port (public Internet) )))((( Wi-Fi Access Point Optional external connection

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

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

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

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

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

RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly Linksys ® Hardware WRT54G (version 2.0): Broadcom MIPS BCM4702KPB, 125MHz, 4MB Flash, 16MB RAM, 5 port 10/100 Ethernet switch, g Broadcom wireless chipset. Broadcom MIPS BCM4702KPB, 125MHz, 4MB Flash, 16MB RAM, 5 port 10/100 Ethernet switch, g Broadcom wireless chipset. WRT54GS (version 1.0): Broadcom MIPS BCM4712KPB, 200Mhz, 8MB Flash, 32MB RAM, 5 port 10/100 Ethernet switch, g Broadcom wireless chipset. Broadcom MIPS BCM4712KPB, 200Mhz, 8MB Flash, 32MB RAM, 5 port 10/100 Ethernet switch, g 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 OpenWRT-based firmware We expanded OpenWRT to support: OLSR implementation (by A. Tønnesen, Th. Lopatic) OLSR implementation (by A. Tønnesen, Th. Lopatic) Auto-configuration scripts for: Auto-configuration scripts for: Network interfaces, DHCP, OLSR, IP Forwarding, Proxy ARP Scripts for collecting performance measurements Scripts for collecting performance measurements Scripts for posting measurements via HTTP to an SQL database Scripts for posting measurements via HTTP to an SQL database User-accessible troubleshooting web Interface for: User-accessible troubleshooting web Interface for: Displaying other Wireless Networks Displaying 1-hop neighbour nodes Displaying LAN, WLAN, WAN ports configuration settings

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

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

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

RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly Experiences Router is easily configured in a timely manner Firmware installation + configuration: 5 minutes Firmware installation + configuration: 5 minutes Node deployment is relatively easy Cabling, packaging, mounting: 2 hours Cabling, packaging, mounting: 2 hours Network stability: Links between nodes with distance up to 300m are stable. Links between nodes with distance up to 300m are stable. Stability is improved as new nodes are added in between other nodes. Stability is improved as new nodes are added in between other nodes. Other factors: antenna, line-of-sight, interference, weather, environment. Other factors: antenna, line-of-sight, interference, weather, environment. High-gain antennas used: 8dBi (up to 300m) High-gain antennas used: 8dBi (up to 300m)Bandwidth: Transfer rates up to 800Kbytes/second (DC++ file transfers during network idle times) 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. 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 Firmware Upgrades There are two methods for upgrading firmware: Partial updates 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 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 Contributions and Achievements Contributions: A complete network architecture for wireless network testbeds A complete network architecture for wireless network testbeds Implementations for two different hardware platforms Implementations for two different hardware platforms Technical Achievements: Compiled firmware for easily configurable, easily deployable, off-the-shelf wireless routers 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 Combined various different network technologies to achieve seamless interoperability with mobile user terminals

RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly 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. 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) Workaround: The client refreshes his IP settings (using DHCP client) Secure, Efficient Network Management in Ad Hoc Networks Automated firmware upgrades on the routers Automated firmware upgrades on the routers Updating router settings Updating router settings

RNP Workshop, 2005, Brazil Nikolaos Tsarmpopoulos, University of Thessaly Research Topics (2/2) Dynamic IP configuration for: Ad Hoc nodes Ad Hoc nodes Improve TCP performance Investigate alternative protocols to TCP, for use over the wireless network Investigate alternative protocols to TCP, for use over the wireless network Design and implement on the routers a “proxy” service. 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) 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). Wi-Fi compliant Access Mechanisms on Wireless Routers. Eliminate the need for additional hardware (Access Points). Perimeter-based AAA Perimeter-based AAA Secure mesh network backbone Secure mesh network backbone

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