Scalable add/drop colorless, directionless, and contentionless optical architectures

A method comprising steps of:

• when a plurality of channels at a Reconfigurable Optical-Add Drop Multiplexer (ROADM) node in an optical network will ingress and egress from a degree in the optical network, such that the plurality of channels are able to share a same physical routing in the optical network because the plurality of channels are each traffic flows that originate and terminate at the ROADM node and a second ROADM node thereby providing a large traffic flow therebetween, connecting the plurality of channels at the degree in the ROADM node, such that the plurality of channels are connected to the second ROADM node in the optical network;
• and
• pre-combining the plurality of channels onto a common port between the degree and the corresponding modems prior to being routed through the optical network, such that the plurality of channels connect to the degree together in a single connection that is co-routed to the second ROADM node, and wherein the plurality of channels are at arbitrary spectral locations, channel bandwidth, modulation formats, or baud rates, relative to one another.