Method of setting up a connection in at least one optical WDM transmission system

A method of setting up a connection in at least one optical WDM transmission system with a plurality of switchable optical network nodes, at least one of the plurality of switchable optical network nodes having a wavelength converter, wherein for setting up a connection from a first optical network node over at least one connection path section to an Nth optical network node, the method comprises the steps of:

• forming a first connection vector for identifying WDM transmission channels available on a following connection path section;
• transmitting the first connection vector over the at least one optical WDM transmission system;
• forming a further connection vector, in the at least one optical network node having a wavelength converter, for identifying the available WDM transmission channels on the following connection path section;
• and
• transmitting the further connection vector over the at least one optical WDM transmission system.