eneralized to be anything that is sufficient to identify a traffic flow. For example, in an optical fiber whose bandwidth is divided into wavelengths, the whole of one wave- length could be allocated to a requested flow-the LSRs at either end of the fiber simply have to agree on which frequency to use. Unlike nongeneralized labels, the data inside the requested flow does not need to be marked with a label value; instead, the label value is implicit in the fact that the data is being transported within the agreed frequency band. On the other hand, some representation of the label value is needed in the signaling protocol SO that control messages between the LSRs can agree on the value to use. GMPLS extends the representation of a label from a single 32-bit num- ber to an arbitrary-length byte array and introduces the Generalized Label object (in RSVP) and Generalized Label Type, Length, and Value (TLV) (in CR-LDP) to carry both the label and related information. The following sub- sections describe how the switching quantities used in optical networks are represented as GMPLS labels. Whole Fiber Labels A link between LSRs may consist of a bundle of optical fibers. LSRs may choose to allocate a whole fiber to a data flow SO GMPLS in Optical Networks they need to agree on which fiber (within the bundle) to use. In this case, the label value is the number of the selected fiber within the bundle. The interpretation of the fiber/port numbers is a local matter for the LSRs on the link. If the two LSRs use different numbering schemes, Link Manage- ment Protocol (LMP)³ provides a mechanism for LSRs to exchange and cor- relate numbering information-see Section 8.6. Wavelength Labels Where the bandwidth of an optical fiber is subdi- vided by wavelength division multiplexing (WDM), an optical LSR may choose to allocate a single wavelength-or lambda-to a requested data flow. In this case, the label value is the wavelength of the selected lambda. Waveband Labels If consecutive wavelengths are grouped together into a waveband, 