Résumé en anglais

We further study some known families of valid inequalities for the 2-edge-connected and 2-node-connected subgraph polytopes. For the 2-edge-connected case, we show that the odd wheel inequalities together with the obvious constraints give a complete description of the polytope for Halin graphs. For 2-node-connected subgraphs, we show that the inequalities above, plus the partition inequalities, describe the polytope for the same class of graphs.