Alcatel-Lucent 7450 Manual page 657

In order to make use of the ECMP next-hop, the user must configure the ecmp value in the system to
at least 2 using the following command:
configure>router>ecmp
In order to make use of the LFA next-hop, the user must enable LFA using the following commands:
config>router>isis>loopfree-alternate
config>router>ospf>loopfree-alternate
Enabling IP FRR or LDP FRR features is not strictly required since LDP only needs to know where
the alternate next-hop to the root LSR is to be able to send the Label Mapping message to program the
backup ILM at the initial signaling of the tree. Thus enabling the LFA option is sufficient. If however,
unicast IP and LDP prefixes need to be protected, then these features and the mLDP fast upstream
switchover can be enabled concurrently.
Note that mLDP FRR fast switchover relies on the fast detection of loss of **LDP session** to the
upstream peer to which primary ILM label had been advertised. As a result it is strongly
recommended to perform the following:
The no form of this command disables the fast upstream switchover for mLDP FECs.
Default
no mcast-upstream-frr
7450 ESS MPLS Guide
• Enable BFD on all LDP interfaces to upstream LSR nodes. When BFD detects the
loss of the last adjacency to the upstream LSR, it will bring down immediately the
LDP session which will cause the IOM to activate the backup ILM.
• If there is a concurrent TLDP adjacency to the same upstream LSR node, enable
BFD on the T-LDP peer in addition to enabling it on the interface.
• Enable the ldp-sync-timer option on all interfaces to the upstream LSR nodes. If an
LDP session to the upstream LSR to which the primary ILM is resolved goes down
for any other reason than a failure of the interface or of the upstream LSR, routing
and LDP will go out of sync. This means the backup ILM will remain activated until
the next time SPF is rerun by IGP. By enabling IGP-LDP synchronization feature,
the advertised link metric will be changed to max value as soon as the LDP session
goes down. This in turn will trigger an SPF and LDP will likely download a new set
of primary and backup ILMs.
Generic Commands
Page 657