RIPv1 (Routing Information Protocol version 1)
A distance-vector routing protocol, dating from the 1980s, that has a maximum hop count of 15. These routers sent out updates every 30 seconds, causing huge network overloads. It was also limited to only working with Classful address, not recognizing CIDR subnets. Plus, it had no authorization mechanism, leaving these routers open to hackers sending false routing table information.