3.3.c Compare routing protocol types

3.3.c [iii] Path vector

Wendell quote:

Like Interior Gateway Protocols (IGP), BGP exchanges topology information in order for routers to eventually learn the best routes to a set of IP prefixes. Unlike IGPs, BGP does not use a metric to select the best route among alternate routes to the same destination. Instead, BGP uses several BGP path attributes (PA) and an involved decision process when choosing between multiple possible routes to the same subnet.

why? bgp is path vector not distance vector… big deal, right…

in the distance part of distance vector you can read metric… a loose definition of vector means direction… metric direction versus AS direction… AS’s versus calculations…