OLSR Simulation and Implementation

Advanced Technology Centre © BAE SYSTEMS 2004. All rights reserved.

OLSR Simulation and Implementation

Christopher [email protected]


Overview

Requirements.

Design Decisions.

Software Organisation.

Compliance, Limitations and Extensions.

Simulation Example.

Ground Sensor Network Demonstration.

Additional Requirements.


OLSR Simulation and Implementation

Requirements

• A framework for a generic AHRP.

• An implementation of OLSR within this framework.

• To be usable to simulate AHRP, e.g. in OPNET.

• To be usable to implement AHRP in real time on e.g. Linux platform. (Laptop or PDA using IEEE 802.11b WLAN.)

• To include IPv4 and IPv6 options.

• To be able to interwork with other implementations of OLSR.

• To add some compliant proprietary extensions to OLSR.

• To allow extension to modified versions of OLSR.

• To support dynamic parameters.


Software Design Decisions

Code to be written in standard C++.

To use object oriented design.

OLSR code to be independent of OPNET and Linux.

OPNET and Linux specific “wrappers” for code.

Separate compilation for IPv4 and IPv6.

Various reporting features.


AHRP and OLSR Classes and Creation

Classes in black existClasses in red are hypothetical

Ahrp

packet_received()routing_failure()link_layer_notification()timeout()

Secure_Olsr

Aodv Olsr

packet_received()routing_failure()link_layer_notification()timeout()

«creation»

«registration» Ahrp_Factory 1

register_creation()create()

Wrapper

«creation»


AHRP and OLSR Class Usage

Routing_Table

add()replace()remove()

Linux_Routing_Table

add()replace()remove()

Packet_Handler

allocate()send()

Linux_Packet_Handler

allocate()send()

Ahrp

Olsr

1

1

Linux_Wrapper1

1

1

1

1 1111


OLSR Software (1)

Initial implementation of OLSRv5, then converted to OLSRv7, then finally to OLSRv11 (RFC 3626).

Some observations from use provided to OLSR authors.

Designed to be fully compliant with OLSR 3626, including

• Multiple interfaces.

• Host and network associations (including dynamic changes).

• Link layer notification and link quality.

• All parameters are configurable (including dynamically).

• IPv4 and IPv6 (separate compilation).


OLSR Software (2)

Current limitations

• Does not piggyback messages, but will process received piggybacked messages.

• No packet size control or message fragmentation, but will handle fragmented messages.

Extensions (all optional)

• Minimum message intervals.

• MPR Set reuse.

• Link layer notification details.

• Use HELLO messages to update Interface Association Set and MID messages to change Two Hop Neighbour Set.


OLSR Simulation Example

Minimum intervals as proportion of normal message interval(link layer notification, medium power, high mobility)

0%

20%

40%

60%

80%

100%

10 30 50 10 30 50

number of nodes number of nodes

pro

po

rtio

n o

f d

ata

re

ce

ive

d

0

10

20

30

40

50

me

an

ov

erh

ea

d (

kb

yte

/s)

zero (fully reactive) quarter interval half interval

zero (fully reactive) quarter interval half interval

Delivery performance Receive overhead per node


OLSR Implementation

Current wrapper is for Linux.

Demonstrated on small mobile networks of laptops and PDAs.

Particular current interest in sensor networks

• Initially stationary.

• Later to add mobile autonomous platform nodes.

Used in

• Operational trials of a BAE SYSTEMS First Generation Unattended Ground Sensor Network in both open terrain and urban environments.

• Collaborative B2NCW (Building Blocks for Network Centric Warfare) programme. (Also looking at reactive protocols.)


Ground sensor node(low power ARM based processor with WLAN,acoustic interface,geo-phone sensor and GPS)

Universal camera node

Demonstration network integrated with an in-service sounding ranging system

Tactical Networkaccess

Avionics GroupSensor SystemsDivision

First Generation UnattendedGround Sensor Network


Sensor Network Trial Results

Mean hop counts from S0

Sensor 1 (S1) 1.74Sensor 2 (S2) 1.07Sensor 3 (S3) 1.01Sensor 4 (S4) 2.75Controller 0 (C0) 1.01Gateway 1 (GW1) 1.54Monitor 1 (M1) 1.02

The non-integer values demonstrate OLSRnetwork reconfigurationduring demonstration

Example ofnetwork topology,as seen from S0 M1

S1

S0

C0S2

S3S4

GW1

0

0.2

0.4

0.6

0.8

1

1.2

00:00:00 01:12:00 02:24:00 03:36:00

Packet receptions at S0 during demonstration


Additional Requirements

The following have been identified as of interest in the development of ad hoc networks, and OLSR in particular

• Security.

• Low power operation (including power control).

• Covertness (possibly including reactive capability).

• Multicast.

• Addressing issues (including IPv6).

• External gateway issues (aggregation, dynamism).


Conclusions

Key points

• Generic ad hoc routing protocol framework.

• Flexible implementation of OLSR.

• Minimum interval extension for highly mobile network.

• Field trials of ad hoc sensor network.

• Additional requirements, especially security.


Contact and Acknowledgements

Christopher Dearlove BAE SYSTEMS Advanced Technology Centre Great Baddow, Chelmsford, Essex, CM2 8HN, UK. +44 1245 242194 [email protected]

The author gratefully acknowledges the support of his colleagues in BAE SYSTEMS plc, Ericsson Microwave Systems AB and Ericsson Telebit A/S, and the support from the UK, Swedish and Danish MoDs under the EUCLID/Eurofinder programme, Project RTP6.22 (B2NCW).

The First Generation Unattended Ground Sensor Network Concept Demonstration was undertaken on behalf of BAE SYSTEMS Avionics Group Sensor Systems Division.

OLSR Simulation and Implementation

Documents

Transcript of OLSR Simulation and Implementation