An entry in this table represents detour LSP or bypass tunnel setup constraints for a tunnel instance to be protected by detour LSPs or a bypass tunnel. Agents must only allow entries in this table to be created for tunnel instances that require fast-reroute as indicated by the presense of the FAST_REROUTE Object in the signaling for the LSP in question, as speciifed in section 4.1 of RFC4090. Entries indexed with fsMplsFrrConstIfIndex set to 0 apply to all interfaces on this device for which the FRR feature can operate. Note that as per [RFC3812] the mplsTunnelInstance object set to a value of 0 indicates that the mplsTunnelEntry contains at a tunnel ingress. This is typically how configuration of this feature is performed on devices where the actual protection LSP used is left up to the protecting tunnel. However, in cases where static configuration is possible, any valid tunnel instance is possible; however, in these cases, it is STRONGLY RECOMMENDED that the instance index SHOULD use the following convention to identify backup LSPs: - lower 16 bits : protected tunnel instance - higher 16 bits: must be all zeros