Switching (MPLS). With FRR, data traffic over a failing MPLS-link is swiftly rerouted through
a pre-provisioned restoration tunnel. The FRR solution works well so long as the restoration
tunnel is not adversely affected by other concurrent failures. Additional protection against
this drawback is offered by the lower (optical) layer, which provides restoration lightpaths to
replace the failing MPLS-link (s). The optical layer can also provide a second remedy, which …