Routing Protocols

are network protocols (that operate at the network layer) used by routers to find all networks in the internetwork, update the routing table, and ensure all routers have the same routing-table. This same table helps routed protocols determine the path of an IP packet through an internetwork
Routing Convergence is the time required by routing protocols to update the routing-tables (forwarding tables) on all routers in a network

Routing Protocols Categories

dynamic routing or static routing
proactive, reactive, or hybrid
unicast routing or multicast routing

Dynamic vs Static

Type	Description
Dynamic Routing Protocols	dynamically updates routing-tables
Static Routing	manual updates routing-tables (rarely used)

Proactive vs Reactive vs Hybrid

Type	Description	Example Routing Protocols
proactive routing	continuously updates routing-tables works well when network topology slowly changes or static	Distance-Vector Open Shortest Path First
reactive routing	only updates routing-tables upon demand (i.e when router receives an IP packet and needs to determine its path through an internetwork) works well when network topology changes frequently can lead to delay and is not appropriate for real-time traffic	On-Demand Distance Vector Dynamic Source Routing
hybrid	a mix of proactive and reactive	Zone Routing Protocol

Unicast vs Multicast

Type	Description
Unicast Routing	updates unicast-routing-tables for unicast forwarding
Multicast Routing	updates multicast-routing-tables for multicast forwarding