IP Router Configuration
Router Configuration Guide 61
Weighted Load-Balancing over Interface Next-hops
When the weighted-ecmp command is configured in the base router context (config>router)
or a VPRN (config>service>vprn), the associated IS-IS instances are allowed to program
IPv4 and IPv6 ECMP routes to use weighted load-balancing across interface next-hops. The
following conditions must be true:
• all ECMP next-hops must be interface next-hops
• all ECMP next-hops must be associated with the same neighbor IS-IS router
• all ECMP next-hop interfaces must have a non-zero load-balancing-weight value
configured in the config>router>isis>interface context
By default, IS-IS interfaces have a zero weight (no load-balancing-weight); non-
zero values must be configured explicitly. Values cannot be auto-derived. The
config>router>isis>interface>load-balancing-weight command accepts a value
between 0 and 4294967295,
If a base router IPv4 or IPv6 BGP route has a BGP next-hop resolved by an ECMP IS-IS route
and ibgp-multipath is configured under BGP, then traffic forwarded to the BGP next-hop is
sprayed according to the load-balancing weights of the interface next-hops.
Process Overview
The following items are components to configure basic router parameters.
• Interface — A logical IP routing interface. Once created, attributes like an IP address,
port, link aggregation group or the system can be associated with the IP interface.
• Address — The address associates the device’s system name with the IP system
address. An IP address must be assigned to each IP interface.
• System interface — This creates an association between the logical IP interface and
the system (loopback) address. The system interface address is the circuitless address
(loopback) and is used by default as the router ID for protocols such as OSPF and
BGP.
• Router ID — (Optional) The router ID specifies the router's IP address.
• Autonomous system — (Optional) An autonomous system (AS) is a collection of
networks that are subdivided into smaller, more manageable areas.
• Confederation — (Optional) Creates confederation autonomous systems within an
AS to reduce the number of IBGP sessions required within an AS.
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