  Since recent RHIC data and the development of new theories for small x
physics, a new interest appeared for forward physics. At LHC, a correct
description of multiple parton interactions will be crucial to understand all
the results. On the other hand, forward particle production and multiple
interactions are the key points of air shower development. That's why air
shower measurements done by precise experiments like KASCADE can help to
understand high energy interactions, using hadronic models which are able to
reproduce both accelerator and air shower data. In the framework of the EPOS
model, we will show what constraints can be fixed by air shower experiment on
particle production from SPS to LHC energies.
