Efficient spectrum allocation in a multi-node optical network

An optical communications network comprising:

• a plurality of optical data links comprising a plurality of data channels;
• one or more optical add-drop nodes communicatively coupled to the plurality of optical data links;
• and
• a system configured to:
• allocate the data channels into bins;
• in response to data channel requests, assign the bins to each of the data channel requests until one bin remains;
• and
• in response to data channel requests for resource sharing in the remaining bin received after one of the bins remains, allocate data channels in the remaining bin using reverse channel assignment wherein data channels for a first and second request are first allocated from opposite ends of the remaining bin regardless of a relative width between the first and second requests, before allocating remaining data channels in the remaining bin while maintaining guard bands between allocated data channels.

A method implemented on an optical communications network comprising a plurality of optical data links comprising a plurality of data channels and one or more switching nodes communicatively coupled to the plurality of optical data links, the method comprising:

• allocating the data channels into bins;
• in response to data channel requests, assigning the bins to each of the data channel requests until one bin remains;
• and
• in response to data channel requests for resource sharing in the remaining bin received after one of the bins remains, allocate data channels in the remaining bin using reverse channel assignment wherein data channels for a first and second request are first allocated from opposite ends of the remaining bin regardless of a relative width between the first and second requests, before allocating remaining data channels in the remaining bin while maintaining guard bands between allocated data channels.