This specifies whether this static tunnel uses a fixed TTL value on the imposed MPLS label or inherits the TTL from the original IP/frame header being encapsulated. An admin sets this to fixed specifically to prevent traceroute or TTL-based diagnostics from revealing internal MPLS core hop counts to end customers, a common security/topology-hiding practice, while inherited TTL preserves normal traceroute behavior for internal troubleshooting. For example, a service provider tunnel set to fixed TTL policy would show a customer's traceroute jumping straight from the ingress PE to the egress PE with no visible core hops.