Supernetting requires the use of routing protocols that support Classless Inter-Domain Routing (CIDR). There are other routing providers and applications listed in the official Routing wiki. The network layer is responsible for packet forwarding including routing through intermediate routers. Some network certification courses distinguish between routing protocols and "routed" protocols. In all versions of Cisco IOS, packet routing and forwarding (switching) are distinct functions. The routing process usually directs forwarding on the basis of routing tables. IPv6 packets using the IPv6 versions of routing protocols. This is useful for debugging network connections or routing tables. In RIPv1 routers broadcast updates with their routing table every 30 seconds. This resulted in slower growth of routing tables in routers. The final office is Routing and Planning which creates bus routes. This has the added benefit of preventing issues with routing protocol loops. For this reason, aggregation is key to scaling unicast routing. This prevents packets from endlessly bouncing around the network in the event of routing errors. This is of interest in network routing and urban transportation systems.