Definitions for "Core gateway"
The primary routers in the Internet.
One of a set of routers with explicit routes to all destinations in an internet. The Internet core system participates in a single routing protocol; all core routers exchange routing updates periodically to ensure that their routing tables remain consistent.
Historically, one of a set of gateways (routers) operated by the Internet Network Operations Center at Bolt, Beranek and Newman (BBN). The core gateway system formed a central part of Internet routing in that all groups must advertise paths to their networks from a core gateway. [Source: MALAMUD