First of all let me discuss the difference between Distance Vector, Link State, and Path Vector routing protocols.
Link state protocols, such as IS-IS and OSPF, rely on each router in the network to advertise the state of each of their links to a network topology map, called a shortest-path tree (The most common shortest path first algorithm is the Dijkstra algorithm). As a router receives an advertisement, it will store this information in a local database, typically referred to as the link-state database, and pass the information on to each of its adjacent peers. This information is not processed or manipulated in any way before it is passed on to the router's adjacent peers.
A router can define the best vector (path) by examining the destinations reachable through each adjacent router or neighbor, combined with some additional information, such as the metric, which indicates the interest of that path. There are two types of vector-based protocols: distance vector and path vector.
Routers running distance vector algorithms advertise the vector (path) and distance (metric) for each destination reachable within the network to adjacent (directly connected) peers. This information is placed in a local database as it is received, and some algorithm is used to determine which path is the best path to each reachable destination. Once the best path is determined, these best paths are advertised to each directly connected adjacent router. Two common algorithms used for determining the best path are Bellman-Ford, which is used by the RIP and RIPv2, and the Diffusing Update Algorithm (DUAL), used by the EIGRP.
Now a path vector protocol does not rely on the cost of reaching a given destination to determine whether each path available is loop-free or not. Path vector (PV) protocols, such as BGP, are used across domains aka autonomous systems. In a path vector protocol, a router does not just receive the distance vector for a particular destination from its neighbor; instead, a node receives the distance as well as path information (aka BGP path attributes), that the node can use to calculate (via the BGP path selection process) how traffic is routed to the destination AS.
