Border Gateway Protocol : EGP protocol which runs between different AS no.
IBGP -- Forming neighborship between routes of same AS
EBGP -- Forming neighborship between routers of different AS
AD -- IBGP 200 EBGP 20
Runs on TCP port no 179
Path attributes : Wellknown ; optional
Wellknown - Mandatory | Discretinary
Optional - Transitive | Non-transitive
Wellknown Mandatory : As-path, origin, Nexthop
Welllknown Discretinary : local-preference , Atomic aggregate
Optional Transitive : Community , Aggregator
Optional Non transitive : MED , Cluster , Weight
Path Selection : We love oranges as oranges meant for pure refreshment.