Alcatel-Lucent 7450 Configuration Manual page 115

ECMP can only be used for routes learned with the same preference and same protocol. See the
discussion on preferences in the static-route command.
When more ECMP routes are available at the best preference than configured in max-ecmp-routes,
then the lowest next-hop IP address algorithm is used to select the number of routes configured in
max-ecmp-routes.
The no form of the command disables ECMP path sharing. If ECMP is disabled and multiple routes
are available at the best preference and equal cost, then the route with the lowest next-hop IP address
is used.
Default no ecmp
Parameters max-ecmp-routes — The maximum number of equal cost routes allowed on this routing table
weighted-ecmp
Syntax weighted-ecmp
no ecmp
Context config>router
Description This command enables the weighted load-balancing, or weighted ECMP, over MPLS LSP.
When this command is enabled, packets of IGP, BGP, and static route prefixes resolved to a set of
ECMP tunnel next-hops are sprayed proportionally to the weights configured for each MPLS LSP in
the ECMP set.
Weighted load-balancing over MPLS LSP is supported in the following forwarding contexts:
IGP computes the normalized weight for each prefix tunnel next-hop. IGP updates the route in RTM
with the set of tunnel next-hops and normalized weights. RTM downloads the information to IOM for
inclusion in the FIB.
7450 ESS Router Configuration Guide
instance, expressed as a decimal integer. Setting ECMP max-ecmp-routes to 1 yields the same
result as entering no ecmp.
Values 0 — 32
• IGP prefix resolved to IGP shortcuts in RTM (rsvp-shortcut or advertise-tunnel-link
enabled in the IGP instance).
• BGP prefix with the BGP next-hop resolved to IGP shortcuts in RTM (rsvp-shortcut or
advertise-tunnel-link enabled in the IGP instance).
• Static route prefix resolved to an indirect next-hop which itself is resolved to a set of equal-
metric MPLS LSPs in TTM. The user can allow automatic selection or specify the names of
the equal-metric MPLS LSPs in TTM to be used in the ECMP set.
• Static route prefix resolved to an indirect next-hop which itself is resolved to IGP shortcuts
in RTM.
• BGP prefix with a BGP next-hop resolved to a static route which itself resolves to set of
tunnel next-hops towards an indirect next-hop in RTM or TTM.
• BGP prefix resolving to another BGP prefix which next-hop is resolved to set of ECMP
tunnel next-hops with a static route in RTM or TTM or to IGP shortcuts in RTM.
IP Router Configuration
Page 115