Mldp Fast Upstream Switchover - Alcatel-Lucent 7450 Manual

Ethernet service switch

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Label Distribution Protocol

mLDP Fast Upstream Switchover

mLDP Fast Upstream Switchover allows a downstream LSR of an multicast LDP (mLDP) FEC to

perform a fast switchover and source the traffic from another upstream LSR while IGP is

converging due to a failure of the primary next-hop of the P2MP FEC. In a sense, it provides an

upstream Fast-Reroute (FRR) capability for the mLDP packets. It does it at the expense of traffic

duplication from two different upstream nodes into the node that performs the fast upstream

When this feature is enabled and LDP is resolving an mLDP FEC received from a downstream

LSR, it checks if an Equal-Cost Multi-Path (ECMP) next-hop or a Loop-Free Alternate (LFA)

next-hop exist to the root LSR node. If LDP finds one, it programs a primary ILM on the interface

corresponding to the primary next-hop and a backup ILM on the interface corresponding to the

ECMP or LFA next-hop. LDP then sends the corresponding labels to the upstream LSR nodes. In

normal operation, the primary ILM accepts packets while the backup ILM drops them. If the node

detects that the interface or the upstream LSR of the primary ILM is down, the backup ILM will

then start accepting packets.

In order to make use of the ECMP next-hop, the user must configure the ECMP value in the

system to at least two (2). In order to make use of the LFA next-hop, the user must enable LFA and

IP FRR options under the IGP instance.

7450 ESS MPLS Guide