um-olsr olsr routing protocol in ns2 郭祐暢 695430044
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UM-OLSROLSR routing protocol in NS2
郭祐暢695430044
Outline
Brief overview of OLSR MPR selection algorithm UM-OLSR install Example UM-OLSR code
Classification
Table drivenSource-Initiated
On demand
DSDV
CGSR
OLSR TBRPF
AODV DSR LMR
TORA
ABR
SSR
Ad Hoc RoutingProtocols
proactive reactive
Optimized Link State Routing Protocol
Proactive & Table-driven Link State Routing
Each node expands a spanning tree Each node can obtain the whole network topology
Utilizes a technique to reduce message flooding MultiPoint Relaying (MPR)
Optimized Link State Routing Protocol Each node periodically floods
status of its links Each node re-broadcasts link state
information received from its neighbors
Each node keeps track of link state information received from other nodes
Each node uses above information to determine next hope to each destination
24 retransmissions to diffuse a message up to 3 hops
Retransmission node
Optimized Link State Routing Protocol Only selected neighbors (MultiPoint
Relays, MPRs) retransmit messages
Select MPRs such that they cover all 2hop neighbors
2-hop neighbors taken from neighbors' HELLO messages
11 retransmission to diffuse a message up to 3 hops
Retransmission node - MPR
Optimized Link State Routing Protocol Three main modules
Neighbor/link sensing Provide topology information up to two hops MPR selector information notification
(“A select B as A’s MPR” in HELLO message to B) Optimized flooding/forwarding
MPR set to cover all the two hop neighbors MPR selector set: set of nodes that select me as one of their
MPR set OLSR-Messages from MPR selector set are to be forwarded
Link-State messaging and route calculation Topology table Route table
MPR selection Each node select a set of MPR Selectors Who can be a MPR Selectors of node N ?
one-hop neighbors of N MPR set of Node N (Rules)
Set of MPR’s is able to transmit to all two-hop neighbors Link between node and it’s MPR is bidirectional.
D
N
B
MX
Y
Z
A
Multipoint Relays (MPR) Every node keeps a table of routes to all known destinatio
n through its MPR nodes
Every node periodically broadcasts list of its MPR Selectors (instead of the whole list of neighbors).
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. Goal : Select in the 1-neighborhood of u (N1(u)) a set of nodes as
small as possible which covers the whole 2-neighborhood of u(N2(u)). Step 1: Select nodes of N1(u) which cover isolated points
of N2(u). Step 2: Select among the nodes of N1(u) not selected at the first step, the node which covers the highest
number of points of N2(u) and go on till every
points of N2(u) are covered.
MPR selection algorithm
First step: Select nodes in N1(u) which cover “isolated points” of N2(u).
u
MPR selection algorithm
Second step : Consider in N1(u) only points which are not already
selected at the first step NPR1(u) and points in N2(u) which are not covered by the NPR1(u) . While there exists points in N2(u) not covered by the selected MPR, select in N2(u), the node which covers the highest number of non-covered nodes in N2(u).
u
MPR selection algorithm
Final : MPRs
u
Installation Download UM-OLSR 0.8.8 from
http://masimum.dif.um.es/?Software:UM-OLSR
Ns2.27 、 2.28 、 2.29 / UM-OLSR 0.8.7 、 0.8.8
Copy um-olsr-0.8.8.tgz to ns-allinone-2.29/ns-2.29/
$ 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 -p1 < olsr/um-olsr_ns-2.29_v0.8.8.patch
$ ./configure
$ make
Example Download olsr_example.tcl from
http://masimum.dif.um.es/um-olsr/olsr_example.tcl
OLSR Hello message one hop for
Two hop topology information MPRs
Transmit two hop top topology information By MPRs TC message
Complete Topology Information Shortest Path Tree calculation (Dijkstra) Routing table build
TC message TC – Topology control message:
Sent periodically. Message might not be sent if there are no updates and sent earlier if there are updates
Contains: MPR Selector Table Sequence number
Each node maintains a Topology Table based on TC messages Routing Tables are calculated based on Topology tables
Topology Table
Destination address
Destination’s MPR
MPR Selector sequence number
Holding time
MPR Selector in the received TC message
Last-hop node to the destination.
Originator of TC message
TC message Upon receipt of TC message:
If there exist some entry to the same destination with higher Sequence Number, the TC message is ignored
If there exist some entry to the same destination with lower Sequence Number, the topology entry is removed and the new one is recorded
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 destinati
ons in the network Routing table is calculated from Topological Table, taking
the connected pairs Routing table:
Destination address Next Hop address Distance
Routing Table is recalculated after every change in neighborhood table or in topological table
UM-OLSR File List (Header) OLSR.h
header file for OLSR agent and related classes OLSR_pkt.h
contains all declarations of OLSR packets and messages OLSR_printer.h
includes all printing functions related to OLSR OLSR_repositories.h
defined all data structures needed by an OLSR node OLSR_rtable.h
header file for routing table's related stuff OLSR_state.h
declares and defines internal state of an OLSR node
UM-OLSR File List OLSR.cc
Implementation of OLSR agent and related classes OLSR_printer.cc
Printing functions used for debugging and tracing are implemented in this file
OLSR_rtable.cc Implementation of our routing table
OLSR_state.cc Implementation of all functions needed for manipulating the interna
l state of an OLSR node