Multicast Ldp Fast Upstream Switchover; Feature Configuration - Alcatel-Lucent 7450 Manual

Multicast LDP Fast Upstream Switchover

Multicast LDP Fast Upstream Switchover
This feature allows a downstream LSR of a multicast LDP (mLDP) FEC to perform a fast
switchover and source the traffic from another upstream LSR while IGP and LDP are converging
due to a failure of the upstream LSR which is the primary next-hop of the root LSR for the P2MP
FEC. In essence it provides an upstream Fast-Reroute (FRR) node-protection capability for the
mLDP FEC packets. It does it at the expense of traffic duplication from two different upstream
nodes into the node which performs the fast upstream switchover.
The detailed procedures for this feature are described in draft-pdutta-mpls-mldp-up-redundancy.

Feature Configuration

The user enables the mLDP fast upstream switchover feature by configuring the following option
in CLI:
configure>router>ldp>mcast-upstream-frr
When this command is enabled and LDP is resolving a mLDP FEC received from a downstream
LSR, it checks if an ECMP next-hop or a 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 both upstream LSR nodes. In normal operation, the primary ILM accepts
packets while the backup ILM drops them. If the interface or the upstream LSR of the primary
ILM goes down causing the LDP session to go 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) 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
Page 572 7450 ESS MPLS Guide