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Routing across wired and wireless mesh networks

8 th International Wireless Communications and Mobile Computing Conference Limassol (Cyprus), August 27-31, 2012. Routing across wired and wireless mesh networks Experimental compound internetworking with OSPF. Juan Antonio Cordero Matthias Philipp Emmanuel Baccelli

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Routing across wired and wireless mesh networks

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  1. 8th International Wireless Communications and Mobile Computing Conference Limassol (Cyprus), August 27-31, 2012 Routing across wired and wireless mesh networks Experimental compound internetworking with OSPF Juan Antonio Cordero Matthias Philipp Emmanuel Baccelli INRIA Saclay – Île-de-France (France)

  2. Agenda • Motivation: compound internetworks in the Internet core • Introduction to OSPF • Our contribution: objectives and experiments • The testbed • Data plane results • Control plane results

  3. Rest of the Internet ‘Compound’ internetworks in the Internet • Set of interconnected wireless and wired networks in a single domain Autonomous System

  4. Rest of the Internet ‘Compound’ internetworks in the Internet • Set of interconnected wireless and wired networks in a single domain Compound Autonomous System

  5. OSPF basic operation • What is OSPF ? • “Open Shortest Path First” • Link-state routing protocol • Main Interior Gateway Protocol (IGP) used in Internet routing • How does it work ? • Packet types Neighbor sensing : Hellos Topology flooding : LS-Updates , LS-Acks Database sychronization : LS-Reqs , DB Description • Interface types (Supported networks) Point-to-point Broadcast MANET-like

  6. Contribution : Objectives and Experiments Extension of OSPF for operation in compound internetworks • Experimental evaluation in a compound internetworking testbed (layer 3 perspective) • Confirm/dismiss underlying assumptions on previous research • On the data plane : UDP flows and pings • On the control plane : OSPF control traffic structure

  7. Testbed description • Wired/wireless static internetwork, 6 computers • MAC layer : 802.3 Ethernet (wired) 802.11b WLAN (wireless) • Routing : OSPF for IPv6 point-to-point interface (wired) MPR-OSPF MANET interface (wireless) 3 with wired interfaces (DECchip 21140) 3 with wireless interfaces (Broadcom BCM4306 WLAN) 2 with wired and wless interfaces (hybrids)

  8. Logical topologies : three scenarios Scenario II Scenario III Scenario I Study of control traffic eth0 S eth1 eth0 S eth1 eth0 S eth1 eth0 eth0 eth0 eth0 eth0 eth0 h1 h2 h1 h2 h1 h2 wlan0 wlan0 wlan0 wlan0 wlan0 wlan0 wlan0 wlan0 wlan0 wlan0 wlan0 w3 w2 w1 w2 w1 w2 w3 w3 wlan0 wlan0 1 wired hop + 1 wireless hop 1 + 2 1 + 3 Data flow (UDP/ICMP)

  9. Physical topology w3 h1 S h2 w2 w1 w3 10 m PC with wired ifs. PC with (only) wless ifs. Computers’ position at the Computer Science Lab of École Polytechnique (LIX, France)

  10. Data plane results UDP data flows ICMP requests (pings) Packet Delivery Ratio (/1) Round Trip Time (msec) m ~ -15% • Quality of communication degrades (almost) linearly as packets traverse more wireless hops

  11. Control plane results : wireless/wired comparison hybrid1:eth1 hybrid1:wlan0 • Periodic pattern in both cases • Different role of flooding in wireless and wired components

  12. Control plane results : OSPF control traffic in wireless • Synchronization traffic is present during the whole lifetime of a wireless (static) link wless3:wlan0

  13. To conclude • Routing with OSPF in compound (wired/wireless) internetworks • OSPF optimization for wireless mesh operation • Link-state synchronization traffic to be minimized • Flooding bursts to be avoided • General observations • Number of wireless links in ‘compound’ routes should be minimized • ‘Optimal’ compound routes are not necessarily those with less hops • Metrics for wireless networks • Integrated shortest-path routing for compound internetworks

  14. Questions ? E-mail : j.a.cordero@gmail.com

  15. Backup slides

  16. Rest of the Internet Compound Autonomous Systems Compound Autonomous System

  17. Testbed configuration details CBR UDP traffic Sender bit rate: 100 pkt/sec Packet payload: 1024 B CBR real effective traffic rate ~ 300 kbps Flow duration: 5 min/flow 60 iterations/value ICMP traffic 84 iterations/value OSPF parameters(common for wired/wireless interfaces, for fairness) HelloInterval: 2 sec DeadInterval: 10 sec RxmtInterval: 5 sec AckInterval: 2 sec MinLSInterval: 5 sec MinLSArrival: 1 sec LSRefreshInterval: 60 secOther parameters IEEE 802.11b: 11 Mbps (nominal data rate), no RTS/CTS, ARQ IP MTU: 1500 B

  18. Physical topology : routes for data flows w3 h1 S h2 w2 w1 w3 10 m 2 hops = 1 + 1 3 h. = 1 + 2 4 h. = 1 + 3 PC with wired ifs. PC with (only) wless ifs.

  19. Link-state routing Link-State Advertisements (LSAs) Link-state Database (LSDB) Shortest Path Tree (SPT) Routing Table ( next-hop ) ( Dijkstra )

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