UMOLSR routing protocol in NS 2 695430044 Outline

UM-OLSR routing protocol in NS 2 郭祐暢 695430044

Outline n n n Brief overview of OLSR MPR selection algorithm UM-OLSR install Example UM-OLSR code

Classification proactive Ad Hoc Routing Protocols reactive Source-Initiated On demand Table driven DSDV OLSR TBRPF CGSR AODV DSR LMR TORA ABR SSR

Optimized Link State Routing Protocol Proactive & Table-driven n Link State Routing n v Each node expands a spanning tree v Each node can obtain the whole network topology n Utilizes a technique to reduce message flooding v Multi. Point Relaying (MPR)

Optimized Link State Routing Protocol Each node periodically floods status of its links n Each node re-broadcasts link state information received from its neighbors n Each node keeps track of link state information received from other nodes n Each node uses above information to determine next hope to each destination n 24 retransmissions to diffuse a message up to 3 hops Retransmission node

Optimized Link State Routing Protocol Only selected neighbors (Multi. Point Relays, MPRs) retransmit messages n Select MPRs such that they cover all 2 hop neighbors n 2 -hop neighbors taken from neighbors' HELLO messages n 11 retransmission to diffuse a message up to 3 hops Retransmission node - MPR

Optimized Link State Routing Protocol n Three main modules v Neighbor/link sensing Ø Provide topology information up to two hops Ø MPR selector information notification (“A select B as A’s MPR” in HELLO message to B) v Optimized flooding/forwarding Ø MPR set to cover all the two hop neighbors Ø MPR selector set: set of nodes that select me as one of their MPR set Ø OLSR-Messages from MPR selector set are to be forwarded v Link-State messaging and route calculation Ø Topology table Ø Route table

MPR selection Each node select a set of MPR Selectors n Who can be a MPR Selectors of node N ? n Y N v one-hop neighbors of N n MPR set of Node N (Rules) X v Set of MPR’s is able to transmit to all two-hop neighbors v Link between node and it’s MPR is bidirectional. M D Z A B

Multipoint Relays (MPR) n Every node keeps a table of routes to all known destination through its MPR nodes n Every node periodically broadcasts list of its MPR Selectors (instead of the whole list of neighbors). n Upon receipt of MPR information each node recalculates and updates routes to each known destination

MPR selection algorithm Each point u has to select its set of MPR. n Goal : n Select in the 1 -neighborhood of u (N 1(u)) a set of nodes as small as possible which covers the whole 2 -neighborhood of u(N 2(u)). v Step 1: Select nodes of N 1(u) which cover isolated points of N 2(u). v Step 2: Select among the nodes of N 1(u) not selected at the first step, the node which covers the highest number of points of N 2(u) and go on till every points of N 2(u) are covered.

MPR selection algorithm u n First step: Select nodes in N 1(u) which cover “isolated points” of N 2(u).

MPR selection algorithm u n Second step : Consider in N 1(u) only points which are not already selected at the first step NPR 1(u) and points in N 2(u) which are not covered by the NPR 1(u). While there exists points in N 2(u) not covered by the selected MPR, select in N 2(u), the node which covers the highest number of non-covered nodes in N 2(u).

MPR selection algorithm u n Final：MPRs

Installation n Download UM-OLSR 0. 8. 8 from http: //masimum. dif. um. es/? Software: UM-OLSR n Ns 2. 27、2. 28、2. 29 / UM-OLSR 0. 8. 7、0. 8. 8 n Copy um-olsr-0. 8. 8. tgz to ns-allinone-2. 29/ns-2. 29/ n $ cd ns-allinone-2. 29/ns-2. 29/ $ tar zxvf um-olsr-0. 8. 8. tgz $ ln -s. /um-olsr-0. 8. 8. /olsr $ patch -p 1 < olsr/um-olsr_ns-2. 29_v 0. 8. 8. patch $. /configure $ make

Example n Download olsr_example. tcl from http: //masimum. dif. um. es/um-olsr/olsr_example. tcl

OLSR n Hello message one hop for v Two hop topology information v MPRs n Transmit two hop topology information v By MPRs v TC message n Complete Topology Information v Shortest Path Tree calculation (Dijkstra) v Routing table build

TC message n TC – Topology control message: v Sent periodically. Message might not be sent if there are no updates and sent earlier if there are updates v Contains: Ø MPR Selector Table Ø Sequence number n Each node maintains a Topology Table based on TC messages v Routing Tables are calculated based on Topology tables

Topology Table Destination address MPR Selector in the received TC message Destination’s MPR Selector sequence number Last-hop node to the destination. Originator of TC message Holding time

TC message n Upon receipt of TC message: v If there exist some entry to the same destination with higher Sequence Number, the TC message is ignored v If there exist some entry to the same destination with lower Sequence Number, the topology entry is removed and the new one is recorded v If the entry is the same as in TC message, the holding time of this entry is refreshed

Routing Table Each node maintains a routing table to all known destinations in the network n Routing table is calculated from Topological Table, taking the connected pairs n Routing table: n v Destination address v Next Hop address v Distance n Routing Table is recalculated after every change in neighborhood table or in topological table

UM-OLSR File List (Header) n OLSR. h l header file for OLSR agent and related classes n OLSR_pkt. h l contains all declarations of OLSR packets and messages n OLSR_printer. h l includes all printing functions related to OLSR n OLSR_repositories. h l defined all data structures needed by an OLSR node n OLSR_rtable. h l header file for routing table's related stuff n OLSR_state. h l declares and defines internal state of an OLSR node

UM-OLSR File List n OLSR. cc l Implementation of OLSR agent and related classes n OLSR_printer. cc l Printing functions used for debugging and tracing are implemented in this file n OLSR_rtable. cc l Implementation of our routing table n OLSR_state. cc l Implementation of all functions needed for manipulating the internal state of an OLSR node