Optimized Link State Routing (OLSR)

This model implements the base specification of the Optimized Link State Routing (OLSR) protocol, which is a dynamic mobile ad hoc unicast routing protocol. It has been developed at the University of Murcia (Spain) by Francisco J. Ros for NS-2, and was ported to NS-3 by Gustavo Carneiro at INESC Porto (Portugal).

The implementation is based on OLSR Version 1 (RFC 3626) and it is not compliant with OLSR Version 2 (RFC 7181) or any of the Version 2 extensions.

Model Description

The source code for the OLSR model lives in the directory src/olsr. As stated before, the model is based on RFC 3626. Moreover, many design choices are based on the previous ns2 model.

Scope and Limitations

The model is for IPv4 only.

• Mostly compliant with OLSR as documented in RFC 3626,
• The use of multiple interfaces was not supported by the NS-2 version, but is supported in NS-3;
• OLSR does not respond to the routing event notifications corresponding to dynamic interface up and down (ns3::RoutingProtocol::NotifyInterfaceUp and ns3::RoutingProtocol::NotifyInterfaceDown) or address insertion/removal ns3::RoutingProtocol::NotifyAddAddress and ns3::RoutingProtocol::NotifyRemoveAddress).
• Unlike the NS-2 version, does not yet support MAC layer feedback as described in RFC 3626;

Host Network Association (HNA) is supported in this implementation of OLSR. Refer to examples/olsr-hna.cc to see how the API is used.

References

[rfc3626]

RFC 3626 Optimized Link State Routing

[rfc7181]

RFC 7181 The Optimized Link State Routing Protocol Version 2

Usage

The usage pattern is the one of all the Internet routing protocols. Since OLSR is not installed by default in the Internet stack, it is necessary to set it in the Internet Stack helper by using InternetStackHelper::SetRoutingHelper

Examples

The examples are in the src/olsr/examples/ directory. However, many other examples esists in the general examples directory, e.g., examples/routing/manet-routing-compare.cc.

For specific examples of the HNA feature, see the examples in src/olsr/examples/.

Helpers

A helper class for OLSR has been written. After an IPv4 topology has been created and unique IP addresses assigned to each node, the simulation script writer can call one of three overloaded functions with different scope to enable OLSR: ns3::OlsrHelper::Install (NodeContainer container); ns3::OlsrHelper::Install (Ptr<Node> node); or ns3::OlsrHelper::InstallAll (void)

Attributes

In addition, the behavior of OLSR can be modified by changing certain attributes. The method ns3::OlsrHelper::Set () can be used to set OLSR attributes. These include HelloInterval, TcInterval, MidInterval, Willingness. Other parameters are defined as macros in olsr-routing-protocol.cc.

The list of configurabel attributes is:

• HelloInterval (time, default 2s), HELLO messages emission interval.
• TcInterval (time, default 5s), TC messages emission interval.
• MidInterval (time, default 5s), MID messages emission interval.
• HnaInterval (time, default 5s), HNA messages emission interval.
• Willingness (enum, default OLSR_WILL_DEFAULT), Willingness of a node to carry and forward traffic for other nodes.

Tracing

The available traces are:

• Rx: Receive OLSR packet.
• Tx: Send OLSR packet.
• RoutingTableChanged: The OLSR routing table has changed.

Caveats

The code does not present any known issue.

Validation

The code validationhas been done through Wireshark message compliance and unit testings.