From the course: CCNP Routing (300-101) Cert Prep: 2 Internet Connectivity

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Path selection

Path selection - Cisco Routers Tutorial

From the course: CCNP Routing (300-101) Cert Prep: 2 Internet Connectivity

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Path selection

- [Instructor] BGP's path selection process is far more involved than a standard IGP. But rather than looking at it as additional complexity, I prefer to see it as additional control opportunities. I'll start by presenting this chart. As routes are learned, if more than one path exists to the same destination subnet, the BGP process will run the routes through this best path algorithm to determine which route to install into the routing table. Step zero is whether the route's next hop is reachable or not. An unreachable next hop via the routing table equals an invalid route. Step one is what the weight of the route is. Weight is a non-transitive attribute, which means it isn't shared among routers. Rather, it's locally significant only. It defaults to zero, and the largest weight wins. This is also user configurable. Step two is which route has the largest local preference? Local preference is a value that is transitive inside of a single ASN. This value is attached to a route and…

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