VMAN
    In ExtremeXOS software,
        Virtual MANs are a bi-directional virtual data connection that creates a private path
        through the public network. One VMAN is completely isolated from other VMANs; the
        encapsulation allows the VMAN traffic to be switched over Layer 2 infrastructure. You
        implement VMAN using an additional 892.1Q tag and a configurable EtherType; this feature is
        also known as Q-in-Q switching.