Chapter 3 Dynamic Routing (Routes and Routing Tables (Ultimate Routes…
Chapter 3 Dynamic Routing
Router rip conf mode
For interfaces not connected to a router, saves resources
reduces security risk
Router rip passive-interface G0/0
ip route 0.0.0.0 0.0.0.0 S0/0/1 interface
Confirm RIP protocol
Any size network
Any topology where multiple routers are needed
Additional Resources needed, CPU and RAM
Route taken is from current topolgy
More complex to implement
hierarchical network topology
Routes and Routing Tables
Routing table entry that contains either a next-hop IPv4 address or an exit interface.
Administrative distance (AD) - Identifies the trustworthiness of the route source.
The AD for static routes is 1 and
the AD for connected routes is 0. Dynamic routing protocols have an AD higher than 1 depending upon the protocol
Identifies how the route was learned.
Identifies the address of the remote network.
Identifies the value assigned to reach the remote network. Lower values indicate preferred routes. The metric for static and connected routes is 0.
Identifies the IPv4 address of the next router to forward the packet to.
Identifies the exit interface to use to forward a packet toward the final destination.
S: Identifies that the route was manually created by an administrator to reach a specific network. This is known as a static route.
D: Identifies that the route was learned dynamically from another router using the EIGRP routing protocol.
O: Identifies that the route was learned dynamically from another router using the OSPF routing protocol.
R: Identifies that the route was learned dynamically from another router using the RIP routing protocol.
A Level 1 parent route. A parent route is a level 1 network route that is subnetted. A parent route can never be an ultimate route
Longest matching route
The best match is the route in the routing table that has the most number of far left matching bits with the destination IPv4 address of the packet. The route with the greatest number of equivalent far left bits, or the longest match, is always the preferred route.
Remember, for any of these routes to be considered a match there must be at least the number of matching bits indicated by the subnet mask of the route.