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Supported Platforms
Understanding BGP Multipath
The Junos OS BGP multipath feature supports the following applications:
- Load balancing across multiple links between two routing devices belonging to different autonomous systems (ASs)
- Load balancing across a common subnet or multiple subnets to different routing devices belonging to the same peer AS
- Load balancing across multiple links between two routing devices belonging to different external confederation peers
- Load balancing across a common subnet or multiple subnets to different routing devices belonging to external confederation peers
In a common scenario for load balancing, a customer is multihomed to multiple routers in a point of presence (POP). The default behavior is to send all traffic across only one of the available links. Load balancing causes traffic to use two or more of the links.
BGP multipath does not apply to paths that share the same MED-plus-IGP cost, yet differ in IGP cost. Multipath path selection is based on the IGP cost metric, even if two paths have the same MED-plus-IGP cost.
