he label values to use on the links that the LSP traverses. Sometimes the network administrator may have additional information about the routing of data traffic as it emerges from the far end of the LSP. For example, he or she may know that only voice telephony traffic will be injected into this LSP, and that upon exit from the LSP, all of this traffic should be routed via a telephony gateway with a well-known address. In such cases, it makes sense to avoid the data packet examination and rout- ing calculation that the egress LSP would otherwise have to perform by sig- naling the well-known gateway address along the LSP. The mechanism to achieve this is called egress label control. The admin- istrator adds additional label objects to the explicit route after the last-hop object. The encoded labels do not have to conform to any standard MPLS label format, but can be anything that makes sense to the egress LSR. When the egress LSR receives the LSP setup message, it notices the addi- tional label objects at the end of the explicit route and interprets them in whatever way it finds useful. 8.3 Out-of-Band Signaling The nongeneralized MPLS signaling protocols presume that the data traf- fic in an LSP will follow the same path as the signaling messages. In opti- cal networks, however, the bandwidth granularity of channels in optical links is high, and it would be wasteful to use an entire bandwidth slice (time slot or wavelength) as a signaling channel. Therefore, there are strong reasons for the signaling to follow an out-of-band path instead of via a con- trol channel that is physically distinct from the data channel. It also sim- plifies the technology that an optical switch needs to implement in its data plane, if the data plane does not need to understand the protocols upon which signaling messages are based. Some solutions use a low-bandwidth link (such as Ethernet) running in parallel to the data channel. Alternatively, it may be that the need to provi- sion a dedicated signaling channel can be avoided by routi