Tracert cannot be carried out on mpls-enabled network; only single destination hop is viewed.
Using MPLS on a device, we cannot reach a loopback0 IP adrress.
Tracert in MPLS domain is different from IP domain. The Loopback ip can not be tracert in MPLS domain. It can use the interface ip to tracert to replace in MPLS domain.
When Mpls was disabled on the device, the loopback was successfully traced.
draft-ietf-mpls-icmp defines the functions and properties to be supported by MPLS enabled devices.