Flexi-grid networks overcomes the fixed grid channel of Wavelength
Switched Optical Network(WSON) by flexible spectrum to allow non-
uniform and dynamic allocation of spectrum based on the demand of the
incoming services' LSP. Flexi-grid networks is an effective solution
to solve the problem of efficient spectrum utilization.
Because the client LSP needs to be assigned contiguous spectrum in
flexi-grid networks, there will be two problems that would affect
spectrum utilization, i.e. RSA and fragmentation. We introduce two
kinds of methods which can improve the spectrum utilization further,
and some related PCEP extensions are defined in this document.