e is received. Optical switches may be relatively slow to program. Although the time to select and adjust the switching components may be quite fast, the time taken for the components to settle down after programming can be much larger-measured in milliseconds. For example, a micromirror can be pro- grammed quickly, but the mirror may take tens of milliseconds to stabilize and stop vibrating after it has been adjusted. It is not safe for an LSR to send a signaling response to its upstream neighbor while the mirror is still vibrating, as the ingress could then send data prematurely and the data would be lost or incorrectly switched. Therefore, the time taken to establish an LSP that traverses n optical LSRs is 2X (end-to-end signaling time) +nX (switch programming and set- tling time). The combination of optical switches and conventional MPLS causes con- siderable latency in LSP setup. Suggested Label To reduce the latency of LSP setup, GMPLS introduces the Suggested Label concept. Each LSR selects a label that it believes will be suitable for use on the link between itself and its downstream partner. It signals this label on the forward signaling path and immediately starts to program its own switch on the assumption that this label is the one that will be agreed on. When the signaling response arrives back at the LSR, the message car- ries a label. If this label confirms the choice suggested on the request, noth- ing further needs to be done because the switch is already programmed. As long as the switch programming has settled down, the signaling response can be forwarded upstream immediately. If the label is different from the one suggested on the signaling request, the switch must be reprogrammed, but nothing is lost compared with the base case where no label was sug- gested. In Figure 8-2, a signaling request is received at an LSR. For the sake of the example, the signaling protocol is RSVP-TE so the message is a Path. The Path message carries a Suggested Label that indicates the label (1a) that the upstream