Zusammenfassung der Ressource
IPv4 Routing Protocols
- Goals
- To dynamically learn and fill the routing table with a route
to each subnet in the internetwork.
- If more than one route to a subnet
is available, to place the best route
in the routing table.
- To notice when routes in the table are no longer valid, and to
remove them from the routing table.
- If a route is removed from the routing table and another route
through another neighboring router is available, to add the route to
the routing table.
- To work quickly when adding new routes or replacing lost
routes. (The time between losing the route and finding a working
replacement route is called convergence time.)
- To prevent routing loops.
- General steps for learning routes
- Step 1. Each router, independent of the routing protocol, adds a route to its
routing table for each subnet directly connected to the router.
- Step 2. Each router’s routing protocol tells its neighbors about the
routes in its routing table, including the directly connected routes,
and routes learned from other routers.
- Step 3. After learning a new route from a
neighbor, the router’s routing protocol adds
a route to its IP routing table, with the
next-hop router of that route typically being
the neighbor from which the route was
learned.