In L4-based systems it is quite common to have multiple applications trying to use the same resource in parallel. One might for instance imagine a setup where multiple L4Linux servers run and try to use the computer's physical network interface. In such cases, the physical resource needs to be multiplexed (or virtualized in new-age termini).
ORe (short for Oshkosh Resurrection) is a best-effort ethernet multiplexer for L4. It provides an abstract send/receive interface for network packets and makes sure that every client gets only those packets it wants to receive. This is achieved by assigning each client a virtual MAC address and filtering packets accordingly.
Using ORe in your application
ORe and L4Linux
There is an ORe stub driver for L4Linux.