Routing

Routing is defined as taking a packet from one device and sending it through the network to another device on a different network. Routers don't really care about hosts - they only care about networks and the best path to each network. The main function of router is to route the packets, to do so a router must have know, the following;

1. Destination address
2. Neighbor routers from which it can learn about remote networks
3. Possible routers to all remote networks
4. The best route to each remote network
5. How to maintain and verify routing information

Router maintains routing information in a table known as routing table.

There are mainly two types of routing: Static and Dynamic

Static Routing: We manually enter the routing information in it's routing table so that, the packets can be routing through the network. E.g. Let's see a scenario here.

Here, without the routing information on two routers (HQ and Remote), the packets from PC0 could not reach PC1. It will only reach up to serial interface of Remote router because the network 192.168.2.0 is connected with HQ router also. so, we enter a routing information on both routers so that, PC0 could ping PC1 and vice Varese.
Pr-configurations on both routers:

1. Basic router configurations such as ; hostname, banner, logging sync, no ip domain-lookup, etc.
2. IP addresses on the required interfaces

Static Routing:
syntax:
HQ(config)# ip route <destination_Network_address> <destination_subnetmask> <gateway_IP> or <interface>
Now,
HQ(config)# ip route 192.168.3.0 255.255.255.0 192.168.2.2
next,
Remote(config)# ip route 192.168.1.0 255.255.255.0 192.168.2.1

To verify the routing information:
HQ# sh ip route

N.B. You can download the packet tracer file here.
Thank You !!