A method of allocating system bandwidth comprising a pre-defined number of physical channels in a wavelength division multiplexed, WDM, optical system including a plurality of terminals (T1, T2, B1, B2, B3, B4, B5, B6) comprising first and second trunk terminals (T1, T2), and a plurality of branch terminals (B1, B2, B3, B4, B5, B6), said method comprising: identifying a connectivity pattern for said system comprising a number of logical terminal-to-terminal connections for said plurality of terminals that is greater than the pre-defined number of physical channels; allocating a first portion of the pre-defined number of physical channels as dedicated channels, each of said dedicated channels for providing dedicated ones of said logical terminal-to-terminal connections only between an associated two of said plurality of terminals; the method further characterized by the steps of: allocating a second portion of the pre-defined number of physical channels as re-used channels by providing said re-used channels in a plurality of separate re-used channel bands, each of said re-used channel bands comprising only associated ones of said re-used channels, and each of said separate re-used channel bands being allocated for providing ones of said logical terminal-to-terminal connections between associated first and second ones of said plurality of branch terminals and for being re-used for providing ones of said logical terminal-to-terminal connections between associated third and fourth ones of said plurality of branch terminals, said associated third and fourth ones of said plurality of branch terminals being different terminals than said associated first and second ones of said plurality of branch terminals; and allocating a third portion of the pre-defined number of physical channels in separate guard bands, each of said guard bands separating associated ones of said re-used channel bands. identifying a connectivity pattern for said system comprising a number of logical terminal-to-terminal connections for said plurality of terminals that is greater than the pre-defined number of physical channels; allocating a first portion of the pre-defined number of physical channels as dedicated channels, each of said dedicated channels for providing dedicated ones of said logical terminal-to-terminal connections only between an associated two of said plurality of terminals; the method further characterized by the steps of: allocating a second portion of the pre-defined number of physical channels as re-used channels by providing said re-used channels in a plurality of separate re-used channel bands, each of said re-used channel bands comprising only associated ones of said re-used channels, and each of said separate re-used channel bands being allocated for providing ones of said logical terminal-to-terminal connections between associated first and second ones of said plurality of branch terminals and for being re-used for providing ones of said logical terminal-to-terminal connections between associated third and fourth ones of said plurality of branch terminals, said associated third and fourth ones of said plurality of branch terminals being different terminals than said associated first and second ones of said plurality of branch terminals; and allocating a third portion of the pre-defined number of physical channels in separate guard bands, each of said guard bands separating associated ones of said re-used channel bands.