In an MPLS network, uniform mode is the default. Uniform mode makes all the nodes that a label-switched path (LSP) traverses visible to nodes outside the LSP tunnel. In contrast, pipe mode acts like a circuit and must be enabled. In pipe mode, when MPLS packets traverse the network, only the LSP ingress and egress points are visible to nodes that are outside the LSP tunnel. To configure pipe mode, include the no-propagate-ttl statement at the [edit protocols mpls] hierarchy level on each router that is in the path of the LSP. The global no-propagate-ttl statement disables time-to-live (TTL) propagation at the router level and affects all RSVP-signaled or LDP-signaled LSPs. Only the global configuration of TTL propagation is supported.
