IP Routing Basics by Networking Hub.

In this blog, I am going to discuss the IP routing process. IP routing is the process of moving packets from one network to another network by using routers. So firstly we have to understand the difference between a routing protocol and a routed protocol.

Routing Protocol:

A Routing protocol is used to dynamically find all the networks in the internetwork and also to ensure that all routers have the same routing table. Generally, a routing protocol determines the path of a packet through an internetwork. Examples: RIP, RIPv2, EIGRP, and OSPF.

Routed Protocol:

When all routers know about all networks, Routed protocols are assigned to an interface and find the method of packet delivery. Examples:  IP and IPv6.

Basic IP Routing:

Once we create an internetwork by connecting our WANs and LANs to a router, we will need to configure logically network addresses (IP), to all hosts in the internetwork, so that they can communicate each other.

Routing term refers to taking a packet from one device and sending it through the network to another device on a different network. 

The router only cares about networks and find the best path to each network.

The logical network address (IP) of the destination host is used to getting the packets to a network through a routed network, and then the hardware address (MAC address) is used to deliver the packet from a router to the destination. The router must know at a minimum the following:

·         Destination address
·         Neighbor routers discovery
·         Possible routes to all remote networks
·         The best route to each remote network
·         How to maintain and verify routing information

If the network is not directly connected to the router, the router must use one of two ways to get to the remote network: static routing meaning is that someone hand type all network locations (destination address, last resort gateway) into the routing table. In static routing, the network administrator is responsible for updating all necessary changes by hand on to all routers.

In the dynamic routing, a protocol on one router communicates with the same protocol running on connected neighboring routers. The routers then update each other about all the routes they know and information saves in the routing table. If any change occurs in the network, the dynamic routing
Protocols automatically inform all routers about the changes.

In dynamic routing we use mainly three types of protocol.

1.      Distance vector Protocol (RIP)
2.      Link State Protocol (OSPF)
3.      Hybrid Protocol. (EIGRP

Administrative Distances:

The administrative distance (AD) is used to rate the trustable information received on a router from a neighbor router. An administrative distance is an integer starting from 0 to 255, where 0 is the most trusted traffic and 255 means no traffic will be passed via this route.

If a router receives two updates listing the same network, firstly router checks is the AD. If one of the advertised routes has a lower administrative distance then the route with the lowest AD will be placed in the routing table.

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