An atmTrail represents an I.326 VC Trail or VP Trail. An atmTrail is always bidirectional. An instance is terminated by an atmNetworkTTP. An instance of this object is created by the managed system or by an action on the vcLayerNetworkDomain or vpLayerNetworkDomain object. The atmTrail object provides connectivity across a specific vcLayerNetworkDomain or vpLayerNetworkDomain. The administrativeState is used for administratively locking and unlocking the atmTrail. When unlocked, the atmTrail functions normally. When in the locked state, the atmTrail is prohibited from the transport of characteristic information. For point to point Subnetwork Connections the a-TPInstance and a single entry in the z- TPList are used to indicate the endpoints. Multiple entries in the z-TPList and the a- TPInstance are used to represent the end points of broadcast (point-to-multipoint), merge (multipoint-to-point), and composite connections. The a-TPInstance identifies the primary endpoint. Only the z-TPList is used identify all end points in a multipoint-to-multipoint connection (there is no primary end point). In this case the a-TPInstance shall be NULL.
Sources for this description
ATM Forum M4 official network view CMIP specifications