BGP vs. IGP: BGP (Border Gateway Protocol) is an exterior gateway protocol (EGP) used to route between autonomous systems, whereas protocols like OSPF and EIGRP are interior gateway protocols (IGPs) used within a single autonomous system.
Neighbor Relationships: BGP forms neighborships explicitly by defining the IP address of the neighbor in the configuration, unlike OSPF and EIGRP which use multicast hello messages to discover neighbors.
Path Selection: BGP uses various path attributes (PAs) for path selection, unlike OSPF which uses bandwidth and EIGRP which uses bandwidth and delay. BGP is categorized as a path vector routing protocol, meaning it knows the direction to a network and the autonomous systems through which the path passes.
Path Selection Parameters: BGP uses multiple criteria to select the best path, including weight, local preference, AS path length, origin type, and MED (Multi-Exit Discriminator).
Order of Preference: These parameters are considered in a specific order, starting with weight and local preference, which are commonly used for outbound path selection.
Memory Aid: An acrostic “We Love Oranges AS Oranges Mean Pure Refreshment” helps remember the key parameters: Weight, Local preference, Originate, AS path length, Origin type, MED, Paths, and Router ID.