Alcatel-Lucent 7450 Manual page 134

RSVP-TE LSP Shortcut for IGP Resolution
3. LFA NH is not computed for the IP primary next-hop of a prefix passed to multicast RTM
4. Multicast RTM is a copy of the unicast RTM and is thus populated with mix of IP and
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.
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even if the same IP primary next-hop ends up being installed in the unicast RTM. The LFA
next-hop will, however, be computed and installed in the unicast RTM for a primary IP
next-hop of a prefix.
tunnel LFA NHs. RPF will succeed for a prefix resolved to a primary or LFA IP NH but
will fail for a prefix resolved to a primary or LFA tunnel NH.
7450 ESS MPLS Guide