Statement introduced in Junos OS Release 11.3.
Support for range from 2 through 20 (for BGP) introduced in Junos OS Release 14.1.
multipath option introduced in Junos OS Release 16.1R2.
Support for 64 BGP add-paths introduced in Junos OS Release 18.4R1 for the MX Series.
include-backup-path and path-selection-mode options introduced in Junos OS Release 18.4R1 for the MX Series and PTX Series.
Enable advertisement of multiple paths to a destination, instead of advertising only the active path.
Range: 1 through 2
For example, if a routing device has four paths to a destination in its routing table and is configured to advertise up to two paths, only contributor paths for load balancing are chosen. The best contributor path is the active path and BGP advertises this path by default. The second best contributor path is selected and this process is repeated until the specified number of paths is reached; in this case, two additional paths to the same destination are selected for load balancing.
Suppose a routing device has in its routing table four paths to a destination and is configured to advertise up to three paths (add-path send path-count 3). The three paths are chosen based on path selection criteria. That is, the three best paths are chosen in path-selection order. The best path is the active path. This path is removed from consideration and a new best path is chosen. This process is repeated until the specified number of paths is reached.
Range: 2 through 64
all-paths—Specify the total number of add-path routes to advertise. BGP advertises all the paths that are allowed by the configured prefix policy and the maximum paths configured using the path-count option.
equal-cost-paths—Specify the equal-cost paths to advertise. You can configure either this option or the multipath option; they are mutually exclusive.
Prefix policies enable you to filter routes on a router that is configured to advertise multiple paths to a destination. Prefix policies can only match prefixes. They cannot match route attributes, and they cannot change the attributes of routes.
The add-path prefix-policy allows up to 64 BGP add-paths to be advertised for a subset of prefixes that match the add-path prefix-policy. To enable this feature for a prefix, the add-path prefix-policy term matching the prefix should have a new then action to set add-path send-count <2...64>. This new action is not applicable if the policy-statement containing it is used in any place other than add-path prefix-policy.
Range: 2 through 64 (for BGP)
This range is applicable only under prefix-policy add-path.
Required Privilege Level
routing—To view this statement in the configuration.
routing-control—To add this statement to the configuration.