Packet-based optical communications networks

In a WDM network, a plurality of the channels are grouped together to form a packet. The format of one of the channels within the packet includes a packet header for providing routing or forwarding information for data on all of the channels of the group. The packet is routed or forwarded by a single port of a switching device in the nodes. This reduces usage of the ports of the switching device, and the invention enables an increase in the data transfer rate without altering the line equipment, as the individual channels still carry data at the same rate.