Which two components need to be configured on both routers?

Answer 1

The question seems to be about getting two routers to communicate.

As we know routers are used to connect separate layer 3 networks. However routers have their own communications protocols such as RIP (routing information protocol) for class-full IP, RIP2 for CIDR (classless inter domain routing protocol). Class-full is the original IP address class definition. Class A, B and C had specific network mask such as 255.0.0.0 for class A, 255.255.0.0 for class B and 255.255.255.0 for class C.

CIDR allows the network mask to be expanded to any length desired to reduce wasted addresses when several sub networks were needed. The term most often used when expanding the network mask is borrowing host bits.

Back to the router question

Both routers must be running matching routing protocols. RIPv4 or OSPF (open shortest path first) for example

Both routers must have an interface on a common network or subnet between them to pass routing information. This same interface will be used to pass all IP traffic once configured.

In the Cisco environment each network the router will route for needs to be added to the router configuration.

Once these basics are achieved routing tables will be built by dynamic updates from other routers.

Output from RIP protocol router below

Routing Protocol is "rip"

Sending updates every 30 seconds, next due in 26 seconds

Invalid after 180 seconds, hold down 180, flushed after 240

10.0.0.0/24 is subnetted, 3 subnets the router has been told to add this network

C 10.1.16.0 is directly connected, FastEthernet0/0 this entry was added when the interface was enabled

R 10.1.17.0 [120/1] via 172.16.1.2, 00:00:20, Serial1/0 this entry is the result of a dynamic update from an adjacent router

R 10.1.18.0 [120/2] via 172.16.1.2, 00:00:20, Serial1/0 this entry is the result of a dynamic update from an adjacent router