What is IP routing?

IP Routing is a process that sends packets from a host on one network to another host on a different remote network. It helps you examine the destination IP address of a packet, determine the next-hop address, and forward it. IP routers use routing tables to determine the next-hop address to which the packet should be delivered.

In CISCO IP routing, data is routed from its source to its destination through routers and across multiple networks. The IP Routing protocols allow routers to build up a forwarding table that correlates final destinations with next-hop addresses.

In this networking tutorial, you will learn:

Routing Metrics

Routing metric are the value that allows the routers to decide the best route for the data packet

Different routing metrics are:

  • Hops
  • Bandwidth
  • Load
  • Cost
  • Reliability

Why Routing Protocols?

Consider the below given image-

How routing protocol works?
  • Should data pass through networks 1, 3, and 5 or networks 2 and 4?.
  • At first glance, data should take the shorter path through networks 2 and 4.
  • But networks 1, 3, and 5 might be faster at forwarding packets than 2 and 4.
  • These are the kinds of choices network routers constantly make.

What is the Default gateway?

A default gateway is a router that hosts use to communicate with other hosts on remote networks. A default gateway is used when a host does not have a route entry for the particular remote network and does not know how to reach that network.

Hosts should be configured to send all packets destined to the default gateway's remote networks, which has a route to reach that specific network.

How does IP routing work?

The following example explains the concept of a default gateway more thoroughly.

Default gateway
  • Host X has an IP address of the router T1 configured as the default gateway address.
  • Here, host X is trying to communicate with host Y, which is a host on another remote network.
  • This host looks up in its routing table to check if there is an entry for the destination network address.
  • If the entry is found, the host will send all data to the router T1.
  • Router T1 then receives the packets and forwards them to host Y.

Routing Table

Every router maintains a routing table which is stored in its RAM. A routing table is widely used by routers to decide the path to the destination network. There are mainly three different methods for populating a routing table:

  • Directly connected subnets
  • Using static routing
  • Using dynamic routing
Routing Table

Types of Routing Protocols

The following protocols help data packets find their way across the Internet:

IP:

The Internet Protocol (IP) specifies the origin and destination for each data packet. Routers inspect each packet's IP header to identify where to send them.

OSPF:

Open Shortest Path First (OSPF) protocol is a link-state IGP tailor-made for IP networks using the Shortest Path First (SPF) method.

RIP:

RIP is used in both LAN and WAN Networks. It also runs on the application layer of the OSI model. The full form of RIP is the Routing Information Protocol. Two versions of RIP are

  1. RIPv1
  2. RIPv2

EIGRP:

It is a hybrid routing protocol that provides routing protocols, distance vector, and link-state routing protocols. It will route the same protocols that IGRP routes using the same composite metrics as IGRP, which helps the network select the best path destination.

ISIS:

ISIS routing protocol is used on the Internet to send IP routing information. It consists of a range of components, including end systems, intermediate systems, areas, and domains.

BGP:

BGP is a routing protocol of the Internet, which is classified as a DPVP (distance path vector protocol). The full form of BGP is the Border Gateway Protocol.

Advantages of IP Routing

The routing process ensures that appropriate packets are routed from the source to the destination

Goals of routing include:

  • It offers stability
  • It provides a robust network
  • Offers dynamic routing update of the network paths
  • Information is safe while transmitting.

What is a router?

Routers are computer networking devices that serve two primary functions:

  • Create and maintain a local area network and
  • Manage the data entering and leaving the network as well as data moving inside of the network.

It also helps you to handle multiple networks and routes network traffic between them. In your home network, your router has one connection to the Internet and one connection to your private local network. Moreover, most routers also contain built-in switches that allow you to connect multiple wired devices.

Functions of Router

Here are important functions of Router:

  • Creates a local area network (LAN).
  • It allows you to split your internet connection to all of your devices.
  • Connect different media and set of devices
  • The routers determine where to send information from one computer to another
  • Packet Forwarding, switching, and filtering.
  • Router also makes sure that information does make it to the intended destination.
  • Connect to a VPN

Summary:

  • IP routing is a process that sends packets from a host on one network to another host on a different remote network.
  • Different routing metrics are: 1) Hops 2) Bandwidth 3) Load 4) Cost and 5) Reliability.
  • A default gateway is a router that hosts use to communicate with other hosts on remote networks.
  • A routing table is used by routers to decide the path to the destination network.
  • Some important routing Protocols are 1) The Internet Protocol 2) Open Shortest Path First (OSPF) protocol 3) RIP (Routing Information Protocol) 4) Intermediate System-to-Intermediate System (ISIS) 5) Enhanced Interior Gateway Routing Protocol(EIGRP) and 5) Border Gateway Protocol (BGP).
  • IP routing offers dynamic routing updates of the network paths.
  • Routers are computer networking devices that serve two primary functions: 1) Create and maintain a local area network, and 2) Manage the data entering and leaving the network.
  • A router helps to determine that information does make it to the intended destination.

 

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