is increases the flexibility of how the network resources can be used. For fiber- and wavelength-based labels, nothing more is needed. When requesting SONET and SDH labels, it may be necessary to request that the total bandwidth for the LSP be split across multiple time slots. Therefore, when the LSP encoding type is SONET or SDH, the Generalized Label Request carries additional fields that specify how many time slots should be combined to meet the request (the Requested Number of Compo- nents [RNC] field) and how those time slots should be concatenated, includ- ing whether they are required to be contiguous (the Requested Grouping Type [RGT] field). 8.2 Constraining Label Choice As described in the previous section, the choice of label for each link is nor- mally dictated by the downstream node on that link. In nongeneralized MPLS, where labels are simply arbitrary numbers (such as ATM VPI/VCIs), this is fine. In GMPLS, where labels are directly related to net- work resources, this can lead to conflicts during LSP setup. For example, an optical switch based on micromirrors may be able to switch a received wavelength from an incoming port to an outgoing port, but may not be able to modify the wavelength. Figure 8-1 shows two LSPs in an optical network where the switches (OXCs) are incapable of wavelength conversion. The solid line LSP runs from optical switch A through B, D, and E to F. The dashed line LSP runs from C through D and E to G. The different line types also represent differ- ent wavelengths in use for the LSPs, where the solid line represents the blue wavelength and the dashed line represents the red wavelength. There Chapter 8 Figure 8-1 Conflict of labels at optical switches. Note: Solid line = blue wavelength Dashed line = red wavelength is no conflict on the link between D and E because the two LSPs use differ- ent wavelengths. However, when LSR C needs to set up a new LSP through D and E to G, it must pick a new wavelength. If the choice is left to LSR G (which would be the normal way of processi