GateD is a modular software program consisting of core services, a routing database, and protocol modules supporting multiple routing protocols (RIP versions 1 and 2, DCN HELLO, OSPF version 2, EGP version 2 and BGP version 2 through 4.) GateD was first used to interconnect the NSFNET and the emerging regional networks, and to implement filtered routing based on policy. GateD allows the network administrator to control import and export of routing information by individual protocol, by source and destination autonomous system, source and destination interface, previous hop router, and specific destination address. The network administrator can specify a preference level for each combination of routing information being imported by using a flexible masking capability. Once the preference levels are assigned, GateD makes a decision on which route to use independent of the protocols involved.
GateD is designed to handle dynamic routing with a routing database built from information exchanged by routing protocols.