Nokia 7705 SAR-W Series - Page 461

MPLS Guide Label Distribution Protocol
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Because LDP can detect the loss of a neighbor/next hop independently, it is possible that it
will switch to the LFA next hop while the IGP (OSPF or IS-IS) is still using the primary next
hop. As well, when the interface for the previous primary next hop is restored, the IGP may
reconverge before LDP completes the FEC exchange with its neighbor over that interface.
This may cause LDP to deprogram the LFA next hop from the FEC and blackhole traffic. In
order to avoid this situation, IGP-LDP synchronization should be enabled on the LDP
interface with the config>router>if>ldp-sync-timer command (refer to the
7705 SAR Router Configuration Guide, “IP Router Command Reference”, for information on
configuring the ldp-sync-timer).
The backup-sr-tunnel option allows an SR tunnel to be used as a remote LFA or TI-LFA
backup tunnel next hop by an LDP FEC. Before this option can be used, the LDP-to-SR
stitching feature must be enabled. See LDP-to-Segment Routing Stitching for IPv4 /32
Prefixes (IS-IS) for more information on this feature.
The no form of this command disables LDP FRR.
Default no fast-reroute
Parameters backup-sr-tunnel — allows an SR tunnel to be used as a remote LFA or TI-LFA backup
tunnel next hop by an LDP FEC
fec-originate
Syntax fec-originate ip-address/mask [advertised-label in-label] [swap-label out-label] interface
interface-name
fec-originate ip-address/mask [advertised-label in-label] next-hop ip-address [swap-label
out-label]
fec-originate ip-address/mask [advertised-label in-label] next-hop ip-address [swap-label
out-label] interface interface-name
fec-originate ip-address/mask [advertised-label in-label] pop
no fec-originate ip-address/mask interface interface-name
no fec-originate ip-address/mask next-hop ip-address
no fec-originate ip-address/mask next-hop ip-address interface interface-name
no fec-originate ip-address/mask pop
Context config>router>ldp
Description This command adds a FEC to the LDP prefix database with a specific label operation on the
node.
Permitted operations are swap to originate a FEC for which the LSR is not egress or pop to
originate a FEC for which the LSR is egress.
For a swap operation, an incoming label can be swapped with a label in the range of 16 to
1048575. If a swap-label is not configured, the default value is 3.