A method by a network node for enabling a first unit to connect or to be connected ad-hoc to a second unit in a system comprising remote radio units and main units, wherein the first unit is a remote radio unit and the second unit is a main unit, or the first unit is a main unit and the second unit is a remote radio unit, which network node is coupled to an optical network; the method comprising: - receiving a connection request from the first unit over the optical network; - establishing a control-plane connection, to the first unit, for control data, wherein the network node comprises at least one virtual master entity and at least one virtual slave entity enabling the establishing of the control-plane connection, wherein said control-plane connection is a Common Public Radio Interface, CPRI, connection, such that the step of establishing a control-plane connection comprises establishing a CPRI connection between said at least one virtual master entity transparently emulating a CPRI master and said first unit acting as a CPRI slave when said first unit is a remote radio unit and establishing a CPRI connection between said at least one virtual slave entity transparently emulating a CPRI slave and said first unit acting as a CPRI master when said first unit is a main unit; - storing control data regarding the first unit, which control data is retrieved from the first unit over the established control-plane connection; - disconnecting the established control-plane connection for control data; and - establishing a data-plane ad-hoc connection between the first unit and the second unit for transferring user data over a determined physical path through the optical network, which determined path is based on the stored control data regarding the first unit and on stored control data regarding the second unit, and wherein the establishing of the data-plane connection is performed after disconnection of the established control-plane connection, wherein said data-plane connection is a CPRI connection and the user data is In-phase Quadrature data. - receiving a connection request from the first unit over the optical network; - establishing a control-plane connection, to the first unit, for control data, wherein the network node comprises at least one virtual master entity and at least one virtual slave entity enabling the establishing of the control-plane connection, wherein said control-plane connection is a Common Public Radio Interface, CPRI, connection, such that the step of establishing a control-plane connection comprises establishing a CPRI connection between said at least one virtual master entity transparently emulating a CPRI master and said first unit acting as a CPRI slave when said first unit is a remote radio unit and establishing a CPRI connection between said at least one virtual slave entity transparently emulating a CPRI slave and said first unit acting as a CPRI master when said first unit is a main unit; - storing control data regarding the first unit, which control data is retrieved from the first unit over the established control-plane connection; - disconnecting the established control-plane connection for control data; and - establishing a data-plane ad-hoc connection between the first unit and the second unit for transferring user data over a determined physical path through the optical network, which determined path is based on the stored control data regarding the first unit and on stored control data regarding the second unit, and wherein the establishing of the data-plane connection is performed after disconnection of the established control-plane connection, wherein said data-plane connection is a CPRI connection and the user data is In-phase Quadrature data.