Team hipercom

Overall Objectives
Scientific Foundations
Application Domains
New Results
Contracts and Grants with Industry

Section: New Results

Integration wireless and backbone

Participants : Cédric Adjih, Emmanuel Baccelli, Thomas Clausen, Philippe Jacquet, Saoucène Mahfoudh, Pascale Minet, Paul Mühlethaler, Georges Rodolakis, Yasser Toor.

Executive summary

We have the following vision: in the future mobile internet and static internet will have their core deeply intricated. This means that mobile ad hoc networks will be attached to the core network, form extension and even be part of it. For example in disaster area, a wireless network could replace the destroyed infrastructure and help to the emergency operations.

With this perspective items such as Autoconfiguration, Security are of crucial importance. However there is a potential conflict between a large population of fixed nodes based on ancient protocol and a smaller but more dynamic population based on new protocols. In the integration both population must cooperate in an hybrid protocol.

The difficulty is to build protocols that are as dynamic and efficient as MANET protocols but can support the legacy of the old and heavy internet protocols. The challenge is nevertheless achievable, because the dynamic part of the network needs less frequent updates from the fixed part of the network. Moreover the natural abondance of resource in the fixed part of the network allows it to support the more frequent updates from the mobile part.

OLSR has been found to be the natural best candidate for this challenge since it gathers dynamic and optimization with internet legacy.

Scientific achievements

Optimized Database exchange and check

The problem of unreliable broadcast and less frequent update is that a missing routing information information can lead to lasting problems (loops, disconnections). We have specified an integrity check of distributed databases. We have replaced the heavy check done in wired world that exchanges database headers line by line by a collective check based on signature broadcast and exchange. That way the routing database are synchronized more quickly and discrepant part identified with a logarithmic cost instead of a cost linear to the database size.


The INRIA proposal is based on OLSR, in particular the optimization feature called MultiPoint Relay. The overhead reduction is similarly based on flooding reduction, and topology reduction. In particular OSPF-MPR supports optimized routing based on general additive metrics as in OSPF and adapt its topology reduction to those metrics. Compared to OLSR, OSPF-MPR has a feature called adjacency reduction inherited from OSPF, using broadcasted acknowledgement that enhances routing database synchronization. This feature is also optimized with MPR.


The MANET extension protocols being largely experimental, we have developped a software that enable a gateway between OSPF and OLSR and allows the convergence of both protocols on existing software. This software has been implemented on the MANET/OLSR demonstrator of CELAR (MoD).


We received support from MoD for this activity.


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