A system comprising: a plurality of disaggregated network elements (102, 104) coupled by a network and not coupled to one another by a common backplane of a chassis; and a controller coupled to the plurality of disaggregated network elements; wherein the plurality of disaggregated network elements include line units defining front panel ports and spine units, the line units all being coupled to the spine units by the network; wherein the plurality of disaggregated network elements are programmed to autonomously: perform discovery of one another over the network; and configure overlay tunnels to and from all ports of the plurality of disaggregated network elements; wherein the controller is programmed to configure each line unit such that: a packet is received on an ingress port of the front panel ports of the each line unit; the each line unit determines an egress port of the front panel ports of a second line unit according to the packet; the each line unit labels the packet with the egress port to obtain a labelled packet; and the each line unit transmits the labelled packet over the network through an overlay tunnel of the overlay tunnels between the ingress port and the egress port. a plurality of disaggregated network elements (102, 104) coupled by a network and not coupled to one another by a common backplane of a chassis; and a controller coupled to the plurality of disaggregated network elements; wherein the plurality of disaggregated network elements include line units defining front panel ports and spine units, the line units all being coupled to the spine units by the network; wherein the plurality of disaggregated network elements are programmed to autonomously: perform discovery of one another over the network; and configure overlay tunnels to and from all ports of the plurality of disaggregated network elements; wherein the controller is programmed to configure each line unit such that: a packet is received on an ingress port of the front panel ports of the each line unit; the each line unit determines an egress port of the front panel ports of a second line unit according to the packet; the each line unit labels the packet with the egress port to obtain a labelled packet; and the each line unit transmits the labelled packet over the network through an overlay tunnel of the overlay tunnels between the ingress port and the egress port. perform discovery of one another over the network; and configure overlay tunnels to and from all ports of the plurality of disaggregated network elements; wherein the controller is programmed to configure each line unit such that: a packet is received on an ingress port of the front panel ports of the each line unit; the each line unit determines an egress port of the front panel ports of a second line unit according to the packet; the each line unit labels the packet with the egress port to obtain a labelled packet; and the each line unit transmits the labelled packet over the network through an overlay tunnel of the overlay tunnels between the ingress port and the egress port. a packet is received on an ingress port of the front panel ports of the each line unit; the each line unit determines an egress port of the front panel ports of a second line unit according to the packet; the each line unit labels the packet with the egress port to obtain a labelled packet; and the each line unit transmits the labelled packet over the network through an overlay tunnel of the overlay tunnels between the ingress port and the egress port.