Paper Title (use style: paper title)
The second option is called medium aggregation where the aggregation only happens in a DTN group level and no aggregation or information hiding is conducted at the intermediate upstream DTN gateway(s). Thus the source knows all the DTN gateways ( L1, L2, N1, and M2) whose groups have members interested in the P2MP session. Thus all the bundles of the P2MP session are transmitted .