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Wireless Solutions in Developing Countries Lessons learned in Latvia and around the World Guntis Barzdins ([email protected]) Taide Network and University of Latvia (Latnet) John Tully ([email protected]) MikroTikls SIA and Latnet Arnis Riekstins ([email protected]) MikroTikls SIA and Polymer Mechanics Institute Agenda Latnet and MikroTikls - who are we? Wireless Internet in Latvia and elsewhere Elements of wireless Internet access Wireless Components Software Issues to Consider: Traditional and New solutions Short history of Wireless Internet in Latvia 1993: first 915MHz WaveLan link in Riga 1994-1996: Latnet wireless network extended 1996: paper “Wireless Internet Access in Latvia” published on the Internet 1996: MikroTikls company founded 1996: By contract with Taide Satellite, MikroTikls installs first 2.4GHz wireless network in Moldova 1996-present: queries from around the World Current Activities Buildings connected to the Internet by 2.4GHz wireless links in Riga : 1997 - More than 100 1998 - More than 200 1999 (May) - More than 300 Also 15 regional cities in Latvia have wireless Internet access Wireless installations & consulting worldwide Development of new wireless solutions Latnet and MikroTikls assisted Wireless installations since 1993 S.KOREA GHANA PERU On-site installation by our staff Equipment supplied or Installation consulted Actual reason for Wireless Wireless Internet is cheaper than Leased line Internet access Other reasons leased lines not available low quality dial-up lines national telecom monopoly quick installation better throughput (up to 11Mb/s) Example from Latvia Wireless is Half-duplex & Multi-point 11Mbps Wireless Internet access Installation 128Kbps Leased line Internet access Installation PC router $450 Wireless card $800 Antenna&cable $250 Leased line installation $900 Cisco router $1400 but 100x faster Monthly fee wireless link $0 Internet $300 Monthly fee leased line $250 Internet $300 What is a Wireless Internet access? Equipment: regular 2.4GHz License-fee wireless LAN Central site omni-directional antenna wireless bridge or access point increased performance increased reliability User site high-gain directional antenna PC router with wireless card router separates user LAN(firewall) back-up routing through dial-up cheaper than WirelessBridge + Cisco router How to make Wireless link cheap but reliable? Components are cheap, integrated solutions are expensive and inflexible. Do it yourself: Which wireless LAN vendor and product to choose? Which parameters matter? What antennas and cables will work the best? Which PC routing software to use? What are known problems with each of them? What communication distances are realistic and what influences that? Will power amplifier extend the range? Wireless LAN Card Vendors our preference Vendor Product Positive Negative Aironet PC4800 up to200mW output ($800) power, hardware error correction Higher price Lucent ISA Technologies Turbo ($500) BreezCom Low cost BreezeL Eexternal unit with two ink antenna connectors. ($1000) Telephone line support Only 20mW output power, short range Degraded performance in “noisy” city environment due to FH radio All listed devices support up to 11 Mbps, operate in 2.4GHz licensefree ISM band, and use Spread Spectrum technology IEEE 802.11 compliance is optional - in “long range” applications top performance can be achieved only with same vendor equipment Antennas & Cables & Connectors Antennas User site:24dBi directional grid antenna Central site:5.58dBi or more Omni-directional antenna Lightning protection! Snow cover in arctic regions Cables L-loss cable designed for 2.4GHz (1dB loss per 1 meter is a ‘good value’) Use short cable! (30m max) Connectors Because of FCC regulations, cards have custom connectors - hard to get, expensive Water in connector is the most frequent problem. Apply HERMETIC our isolation to suggestion connectors ALWAYS! Environmental Aspects Direct line of sight required Rain and snow has no influence on the link Distances: Distance calculator: 12km radius around the Access Point for • cable length point-to-multipoint connections (4km with • antenna gain • speed ETSI compliant antennas) • power 40km between two nodes with directional http://www.ltn.lv/ antennas for point-to-point links (10km with ~guntis/smarp/ ETSI compliant antennas) our suggestion Amplifiers amplify also noise - avoid them! PC routing software DOS and Windows Windows NT (too bulky) Windows 95/98 cannot route! DOS based IP routers (up to 2Mbps only!) PCroute our preference has no remote, VLSM (free) IProute by Dave Mischler (license $50) KA9Q, JNOS, TNOS,... (free, but slow and unreliable) PC Routing Software - UNIX Linux Router Project good, but few wireless cards have working Linux drivers our preference FreeBSD based router - same problem MicroTik wireless router software(Linux based) supports most Wireless and ordinary NICs remote management via telnet and http wireless network diagnostics & testing options commercial version $300 New! Use Aironet Bridge as a Router Price: PC+WirelessCard=WirelessBridge Bridge works at -20C: can be mounted at antenna outdoors (increased range) Bridge acts as a repeater: micro-cells Bridge can be configured to: Forward all unicast frames Discard all multicast/broadcast frames Filter frames on additional header fields Server-based ARP needed: SmartARP New! SmartARP configuration Free SmartARP for Win95 and LINUX at: http://www.ltn.lv/~guntis/smarp/ Configuration file of SmartARP server A: 10.1.1.0 10.1.2.0 10.1.3.0 10.1.4.0 255.255.255.0 255.255.255.0 255.255.255.0 255.255.255.0 Ranges of IP addresses assigned client networks local forward 00:01:3a:4c:12 forward 00:73:18:a5:62 forward 00:0c:63:52:7a What to do with ARP requests MAC address of smartARP server B MAC address of smartARP server C MAC address of smartARP server D Future Routing and VLANs complex to manage with 100s of permanently connected customers (with backup links) Max auto-configuration is needed: Bridging with IP prefix filter vs. Routing Substitute for inefficient Spanning Tree Protocol (STP) used by Bridges Traditional IP router IP range Next Hop IP 192.12.76.0/24 194.42.32./28 198.4.15.0/24 199.1.2.13 193.5.77.1 199.1.2.13 Routing table Bridge with IP filter, no STP IP addr 199.1.2.13 193.5.77.1 MAC addr 00:14:0c:76:82 00:0c:21:44:15 ARP table IP range 192.12.76.0/24 194.42.32./28 198.4.15.0/24 Next Hop MAC 00:14:0c:76:82 00:0c:21:44:15 00:14:0c:76:82 IP forwarding table Conclusion: Preferred Solution Aironet 11Mbps Turbo DS Bridge BR500-E or AP4800 (central site) PCrouter with ISA or PCI4800 (client) TREND: Use wires and same software to share Internet connection with neighbors Routing software IPRoute ($50) MikroTik router software ($300) SmartARP software (free) Quality Cables, Antennas, Connectors Up to 20 clients per cell of 7-12km radius (in city environment use 1-2km micro-cells + microwave or fiber backbone) References Slides available at: http://www.ltn.lv/~guntis/smarp/ Latnet (operates wireless network in Latvia) http://www.latnet.lv MikroTikls (wireless hardware & software) http://www.mt.lv Taide Network (satellite communications) http://www.taide.net
