Routing Tables and Dynamic Routing Protocols

When the route entry indicates that the destination IP address is on a remote network, the packet must be forwarded to the next-hop router. The next-hop address is indicated in the route entry. If the forwarding router and the next-hop router are on an Ethernet network, a process involving ARP and ICMPv6 Neighbor Discovery occurs to determine the destination MAC address of the packet. The router will search for the IP address of the next-hop router in its ARP table or neighbor cache, instead of the destination IP address of the packet.

If there is no match between the destination IP address and a prefix in the routing table, and if there is no default route, the packet will be dropped.

Process switching, Fast switching, Cisco Express Forwarding (CEF)

It involves CPU matching destination address with routing table entry for every packet, which can be inefficient for high traffic loads

It uses a fast-switching cache to store next-hop information for efficient packet forwarding

CEF is the most recent and default packet forwarding mechanism, building a Forwarding Information Base (FIB) and adjacency table for efficient packet forwarding

Route source, destination network, administrative distance, metric, next-hop, route timestamp, and exit interface

They are configured as active interfaces with IP address and subnet mask, denoted by status code C

It indicates a local route for each directly connected network, with prefix length /32 for IPv4 and /128 for IPv6

Static routes are commonly used in smaller networks, for single default route, and for routing to and from stub networks

They define explicit paths between networking devices and must be manually reconfigured if network topology changes

The FIB is used to store the best paths for forwarding packets to their destination networks

The adjacency table is used to store the Layer 2 next-hop addresses for efficient packet forwarding

Static routes are manually configured and used for ease of routing table maintenance, but must be manually reconfigured if network topology changes

EIGRP calculates metric based on bandwidth, delay, load, and reliability

Equal cost load balancing forwards packets using multiple paths with equal cost metrics

Load balancing can enhance network performance when configured correctly

EIGRP is the only protocol supporting unequal cost load balancing

Routers determine best paths based on routing table information

Directly connected networks are added to the routing table when active

Routers learn about remote networks through static routes and dynamic routing protocols

Routers support process switching, fast switching, and CEF for packet forwarding

Various commands like show ip route and show running-config are used for router configuration and verification

Routing table includes routes from directly connected networks, static routes, and dynamic routing protocols

Routing information is local to each router and does not provide return routing information

Administrative distance (AD) determines the route to install into the IP routing table

The purpose of dynamic routing protocols includes the discovery of remote networks, maintaining up-to-date routing information, and choosing the best path to destination networks.

A stub network is accessed by a single route with a router having only one neighbor.

OSPF is being used in the sample topology.

The default route specifies a next-hop router to use when the routing table does not contain a specific route that matches the destination IP address.

The main components of dynamic routing protocols include data structures, routing protocol messages, and algorithms.

The best path is selected by a routing protocol based on the value or metric it uses to determine the distance to reach a network.

RIP uses 'hop count' and OSPF uses 'cost' as their metrics.

IPv4 was standardized using the now obsolete classful addressing architecture.

A routing protocol is a set of processes, algorithms, and messages used to exchange routing information and populate the routing table with the choice of best paths.

A stub network.

IPv4 and IPv6 static routes are configured on R1.

OSPF routing configuration for IPv4 and IPv6 is beyond the scope of this course.