A switching module (100; 302, 304; 400; 602, 604, 606; 702, 704, 706, 708, 710; 802, 804, 806, 810, 812, 816) comprising: a first port group comprising at least one source port, wherein each source port in the first port group is configured for connecting with a data source, the switching module being characterized in that: each source port in the first port group is further configured for modifying a data frame transmitted by the connected data source by including in the data frame a unique port number, comprising a source chip ID and a source port number, assigned to the source port, and a virtual local network identifier, VLAN ID, specified by a central processing unit, and for routing the modified data frame to a destination port if a unique port number assigned to the destination port is associated with that VLAN ID in a routing table assigned to the source port; and wherein the switching module further comprises: a second port group comprising at least one port, wherein each port in the second port group is configured for connecting with a monitoring station, and receiving a data frame modified by at least one source port in the first port group; and a control unit (106; 306) for assigning a unique port number to each source port in the first port group and to each port in the second port group, and for assigning to each source port in the first port group a routing table including at least one source port number and at least one destination port number associated with the at least one source port number. a first port group comprising at least one source port, wherein each source port in the first port group is configured for connecting with a data source, the switching module being characterized in that: each source port in the first port group is further configured for modifying a data frame transmitted by the connected data source by including in the data frame a unique port number, comprising a source chip ID and a source port number, assigned to the source port, and a virtual local network identifier, VLAN ID, specified by a central processing unit, and for routing the modified data frame to a destination port if a unique port number assigned to the destination port is associated with that VLAN ID in a routing table assigned to the source port; and wherein the switching module further comprises: a second port group comprising at least one port, wherein each port in the second port group is configured for connecting with a monitoring station, and receiving a data frame modified by at least one source port in the first port group; and a control unit (106; 306) for assigning a unique port number to each source port in the first port group and to each port in the second port group, and for assigning to each source port in the first port group a routing table including at least one source port number and at least one destination port number associated with the at least one source port number. each source port in the first port group is further configured for modifying a data frame transmitted by the connected data source by including in the data frame a unique port number, comprising a source chip ID and a source port number, assigned to the source port, and a virtual local network identifier, VLAN ID, specified by a central processing unit, and for routing the modified data frame to a destination port if a unique port number assigned to the destination port is associated with that VLAN ID in a routing table assigned to the source port; and wherein the switching module further comprises: a second port group comprising at least one port, wherein each port in the second port group is configured for connecting with a monitoring station, and receiving a data frame modified by at least one source port in the first port group; and a control unit (106; 306) for assigning a unique port number to each source port in the first port group and to each port in the second port group, and for assigning to each source port in the first port group a routing table including at least one source port number and at least one destination port number associated with the at least one source port number. a second port group comprising at least one port, wherein each port in the second port group is configured for connecting with a monitoring station, and receiving a data frame modified by at least one source port in the first port group; and a control unit (106; 306) for assigning a unique port number to each source port in the first port group and to each port in the second port group, and for assigning to each source port in the first port group a routing table including at least one source port number and at least one destination port number associated with the at least one source port number.