BGP Path Selection
IGPs, such as EIGRP or OSPF, choose routes based on lowest metric. They
attempt to find the shortest, fastest way to get traffic to its destination. BGP,
however, has a very different way of route selection. It assigns various
attributes to each path; these attributes can be administratively manipulated
in order to control the path that is selected. It then examines the value of
these attributes in an ordered fashion until it is able to narrow all the possible
routes down to one path.