Emulatore di Protocolli di Routing per reti Ad-hoc Alessandra Giovanardi DI – Università di Ferrara Pattern Project Area 3: Problematiche di instradamento

Scenario Campus: student informations, group studies, game activities

Research activities Phase 1: Studies, theoretical and simulative (SAM), to investigate energy efficient routing protocols Phase 2: Emulation approach to investigate routing protocols for ad hoc networks and to give preliminary results on energy efficiency  interface with SAM

Test Environments Emulates any degree of "real-world badness" in a small, lab - environment network Involves hardware or firmware components of the systems Provides a means for simulations to interact with a live environment Emulation Simulation Cheap and quick to assemble, can do large-scale tests, tests are controlled and reproducible May only be possible very late in development cycle Live tests Can be very slow, its implementation may differ considerably from real one Can give a controlled, reproducible environment for running live code It is often difficult or too expensive to create a real test environment of any significant size Real environment tests also tend not to be reproducible

Emulator Structure Developed in the user space. Can check the performance of any kind of routing protocol, in a wireless environment. Created an interface to the SAM simulator, where many kinds of ad hoc routing protocols are implemented. Based on the libpcap library and on the use of RAW sockets. Integrated with a statistic module (performance indexes). Two logical modules: send packet generation and transmission analyzer packet dump and forwarding (router) Developed and tested on a cluster of Linux hosts with same filesystem Hosts connected by an Ethernet network, but the framework is general (IEEE )

Emulator Structure con’td

Network Organization N hosts identified by logical number n Packet generation can be activated in all hosts in the network or in a subset of them (Na < N) All N hosts have router functions Na ns nd N

Analyzer Module cont’d Packet dump Type 0x0020 ? no ns, nd, TTL, Timestamp and nlast-hop evaluation Channel test ok ? Packet drop  statistics no yes Packet forwarding ? no yes TTL=TTL-1 TTL=0 ? Error message + packet drop yes no Packet reaching final target  statistics Next hop evaluation (Routing block) + packet transmission  statistics

Send Module Selection of Na transmitting hosts Generation of the frame: -arrival time (Poisson distribution or deterministic) -destination nd (uniform distribution) -timestamp (collection of the generation time) -TTL -payload Evaluation of the next-hop (Routing block) Creation of the frame and insertion on the network (RAW sockets) Collection of statistics on packets effectively sent or dropped

Implementation problems Host synchronization (delivery time) Kernel and interface packet drop Transparent interface with SAM centralized structure (packet conversion, routing informations management, Temporization..)...

Synchronization To collect the delivery times, hosts must be synchronized NetworkTime Protocol (NTP) can gain in some cases an accuracy of 1ms, often it can cause a mismatch in the time synchronization up to 0.5s We decided to compute the delivery time at the host having generated the timestamp, i.e., at the source node ns Time accuracy growths with the number of nodes relaying the packet Time signalling packet (ns=0) nsnd

Statistics Each node can be involved in the collection of parameters needed to evaluate final performance Many output files are created, characterized by a prefix identifying the logical number n of the node Performance indexes: -average success probability Psucc (correctly delivered packet fraction) -delivery time Tacc (end-to-end time) -average number of hops in the path Hop -number of isolated nodes Output files collect information on: -packets sent or dropped at the source -packets sent or dropped at each relaying node -packets correctly received or not (channel errors) by the destination

Conclusions Proposal of a general emulation framework for routing protocols in wireless environment Work in progress: tests with a simple routing protocol (Dijkstra) without mobility Future works: -investigation and emulation of ad hoc network routing protocols (DSR,AODV) -attention to energy efficiency, network life time etc.