Peers
Initially NSFNET had only one connection to ARPANET (router in Pittsburg) => only one route between the two.
Addition of multiple interconnections => multiple possible routes => need for dynamic routing decision
Single core replaced by a network of peer backbones => more scalable
- Today there are over 30 backbones!
The routing protocol used by cores & peers was called Gateway-Gateway Protocol (GGP). Replaced by EGP and now by BGP-4.