The Internet uses hierarchical networking, for scalability and manageability reasons. However the main ad hoc routing solutions (OLSR, AODV, DSR, TBRPF) only provide flat networking, and generally suffer important scalability issues. This paper therefore introduces a simple mechanism providing dynamic clustering with OLSR, one of the MANET routing solutions, chosen for its easy integration in the Internet infrastructure. The paper then describes how this dynamic clustering can be used to provide MANET hierarchical networking with OLSR.