Configuring Border Gateway Protocol (BGP) (Packet Tracer)

Configuring Border Gateway Protocol (BGP) (Packet Tracer)
“Border Gateway Protocol (BGP) is a standardized exterior gateway protocol designed to exchange routing and reachability information between autonomous systems (AS) on the Internet. The protocol is often classified as a path vector protocol but is sometimes also classed as a distance-vector routing protocol.”
To determine the best path to an AS, the algorithm compares each valid path with all other paths in a routing table according to the following criteria:

Weight – A Cisco-defined attribute that is local to the router on which it was configured. Weight is higher by default for routes that originate at the router. If there are multiple paths to a given IP address, BGP chooses the route with the highest weight.
Local Preference – The preferred path for exiting the AS to reach a certain network. The default is 100, but paths with higher weights are given priority. Routers within the same AS share the local preference attribute.
Locally Generated – Selects a path that originates locally via an aggregate or a network. The aggregation of network routes saves space in the routing table.
Shortest AS_Path – Selects an AS path for each route, which shows the number of AS hops to reach a given destination. This selection criterion chooses the shortest AS path, i.e., the path with the fewest hops.
Lowest Origin Type – Assigns higher preference to Exterior Gateway Protocol (EGP) vs. Interior Gateway Protocol (IGP).