3.7.c Explain attributes and best-path selection

R4#sh ip bgp | b Net
Network          Next Hop            Metric LocPrf Weight Path
*>  10.1.30.0/24     3.3.3.3                                0 123 678 ?
*>  10.1.31.0/24     3.3.3.3                                0 123 678 ?
*>  10.1.68.0/24     3.3.3.3                                0 123 678 ?
*>  10.1.69.0/24     3.3.3.3                                0 123 678 ?

r4 learned these networks from the next hop 3.3.3.3 which is in AS 123 which learned them from AS 678 which learned them from some other source (redistribution)

hit it wendell:

 a router can add entries to its BGP table using the network command and route redistribution. Additionally, BGP can use manual route summarization to advertise summary routes to neighboring routers, causing the neighboring routers to learn additional BGP routes. BGP manual summarization with the aggregate-address command differs significantly from using the auto-summary command. It can summarize based on any routes in the BGP table, creating a summary of any prefix length. It does not always suppress the advertisement of the component subnets, although it can be configured to do so.