Alcatel-Lucent 7950 SR User Configuration Manual page 87

Disabling TTL Propagation in an LSP Shortcut
This feature provides the option for disabling TTL propagation from a transit or a locally
generated IP packet header into the LSP label stack when an RSVP LSP is used as a shortcut for
BGP next-hop resolution, a static-route next-hop resolution, or for an IGP route resolution.
A transit packet is a packet received from an IP interface and forwarded over the LSP shortcut at
ingress LER.
A locally-generated IP packet is any control plane packet generated from the CPM and forwarded
over the LSP shortcut at ingress LER.
TTL handling can be configured for all RSVP LSP shortcuts originating on an ingress LER using
the following global commands:
config>router>mpls>[no] shortcut-transit-ttl-propagate
config>router>mpls>[no] shortcut-local-ttl-propagate
These commands apply to all RSVP LSPs which are used to resolve static routes, BGP routes, and
IGP routes.
When the no form of the above command is enabled for local packets, TTL propagation is
disabled on all locally generated IP packets, including ICMP Ping, trace route, and OAM packets
that are destined to a route that is resolved to the LSP shortcut. In this case, a TTL of 255 is
programmed onto the pushed label stack. This is referred to as pipe mode.
Similarly, when the no form is enabled for transit packets, TTL propagation is disabled on all IP
packets received on any IES interface and destined to a route that is resolved to the LSP shortcut.
In this case, a TTL of 255 is programmed onto the pushed label stack.
7950 SR OS MPLS Configuration Guide
MPLS and RSVP
Page 87