The entity hierarchy of the LAPB module is:

    Node___LAPB____Link
                 |
                 |_Port

    The LAPB entity is the top-level entity in the LAPB module
    hierarchy of entities. The LAPB module implements the LAPB
    link-level protocol which is a variation of the HDLC link-level
    protocol.

    A LAPB LINK entity is associated with a port of the supporting
    Physical layer, and contains attributes that describe local LAPB
    operation. The simple-name refers to the link managed by this
    command.

    A LAPB PORT entity represents an access point for LAPB module
    clients to Data Link layer services. The port-name refers to the
    port managed by this command.