Routers can route in two basic ways. They
can use preprogrammed static routes, or they can dynamically
calculate routes using any one of a number of dynamic routing protocols.
Dynamic routing protocols are used by routers to discover routes.
Routers then mechanically forward packets (or datagrams) over those
routes.
Statically programmed routers cannot discover routes; they lack any
mechanism to communicate routing information with other routers.
Statically programmed routers can only forward packets using routes
defined by a network administrator.
In addition to static programming of routes, there are three broad
categories of dynamic routing protocols:
- Distance-vector
- Link-state
- Hybrids
The primary differences between these types of dynamic routing
protocols lie in the way that they discover and calculate routes to
destinations