What is IP Routing? Types, Routing Table & Protocols

By : Bryce Leo Bryce Leo
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⚡ Smart Summary

IP Routing moves data packets from a source host to a destination host across separate networks, and it relies on routing tables, next-hop logic, and routing protocols to choose the fastest, most reliable path between endpoints.

  • 📡 Core Concept: IP Routing inspects the destination IP in each packet header and forwards it to the next-hop router until it reaches the target network.
  • 🗺️ Routing Tables: Routers store directly connected subnets, Static Routing entries, and Dynamic Routing updates in RAM to map paths to remote destinations.
  • ⚡ Key Metrics: Path selection depends on hop count, bandwidth, load, cost, and reliability values calculated by the routing process.
  • ✅ Modern Protocols: OSPFv3, BGP, EIGRP, RIPv2, and IS-IS handle IPv4 and IPv6 traffic across enterprise and internet-scale networks.
  • 🛠️ Default Gateway: Hosts forward packets bound for unknown remote networks to a configured gateway router that owns the next-hop path.
  • 🤖 AI Assistance: Machine learning models now flag routing anomalies and suggest path optimizations that traditional metric-based algorithms miss.
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What is IP Routing?

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. IP routing protocols allow routers to build a forwarding table that correlates final destinations with next-hop addresses, supporting both IPv4 and IPv6 traffic in modern networks.

Why is IP Routing Important?

Without IP Routing, data packets cannot leave their local subnet. Every modern application, from web browsing to cloud workloads, depends on routers exchanging reachability information so packets reach the correct destination across multiple administrative domains.

IP Routing also supports redundancy. When a primary path fails, dynamic protocols recalculate routes within seconds, keeping services available and predictable for users.

Routing Metrics

A routing metric is the value that allows routers to decide the best route for a data packet. Lower-metric paths are typically preferred when multiple routes lead to the same destination.

Different routing metrics are:

  • Hops
  • Bandwidth
  • Load
  • Cost
  • Reliability

Why Routing Protocols?

Consider the image below.

How Routing Protocol Works
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 for remote networks to the default gateway, which has a route to reach the specific destination network.

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How Does IP Routing Work?

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

Default Gateway

Default gateway
  • Host X has the IP address of 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 its routing table to check whether there is an entry for the destination network address.
  • If the entry is found, the host will send all data to router T1.
  • Router T1 then receives the packets and forwards them to host Y.

Routing Table

Every router maintains a routing table that 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

Routing Table

Types of Routing Protocols

The following protocols help data packets find their way across the Internet. Each protocol uses a different algorithm to compute the best path.

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. Both IPv4 and IPv6 use the same routing principles.

OSPF

Open Shortest Path First (OSPF) is a link-state Interior Gateway Protocol tailor-made for IP networks using the Shortest Path First method. OSPFv3 extends the protocol to support IPv6 addressing.

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

Enhanced Interior Gateway Routing Protocol is a hybrid routing protocol that combines distance-vector and link-state behaviors. It routes the same protocols as IGRP using the same composite metrics, helping the network select the best path to a destination.

IS-IS

The IS-IS 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 the routing protocol of the Internet, classified as a path-vector protocol. The full form of BGP is the Border Gateway Protocol, and it is the standard for exchanging routing information between autonomous systems.

Static Routing vs Dynamic Routing

Static Routing requires an administrator to enter routes manually, which works well for small, stable networks. Dynamic Routing protocols, including OSPF, BGP, and EIGRP, learn routes automatically and react to topology changes without manual updates.

Large enterprises and service providers typically combine both: Static Routing for predictable default paths and Dynamic Routing for resilience.

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 updates 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.
  • Manage the data entering and leaving the network, as well as data moving inside the network.

A router also helps you 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. Most routers also contain built-in switches that allow you to connect multiple wired devices.

Functions of a Router

Here are important functions of a router:

  • Creates a local area network.
  • It allows you to split your internet connection across all your devices.
  • Connects different media and sets of devices.
  • The router determines where to send information from one computer to another.
  • Packet forwarding, switching, and filtering.
  • The router also makes sure information reaches the intended destination.
  • Connects to a VPN.

Important IP Route Commands

The following two IP route commands are used to configure a static route on a Cisco router.

Router(config)# ip route destination_network_# [subnet_mask] IP_address_of_next_hop_neighbor [administrative_distance] [permanent]

OR

Router(config)# ip route destination_network_# [subnet_mask] interface_to_exit [administrative_distance] [permanent]

FAQs

The two main IP route commands used to configure a static route on a Cisco router specify either the next-hop neighbor IP or the exit interface, along with optional administrative distance and permanent flags.

IP addresses route packets of data from one computer or server to another until they reach the destination on the Internet using a routing algorithm and hop-by-hop forwarding decisions made by each intermediate router.

The protocol used to route IP addresses is the Internet Protocol, which specifies each data packet’s origin and destination. Routing protocols such as OSPF, BGP, and EIGRP populate the forwarding tables that IP relies on.

Static Routing relies on manually configured entries, while Dynamic Routing uses protocols such as OSPF, RIP, EIGRP, and BGP to learn and update routes automatically as the network topology changes.

Yes. Modern routers run protocols such as OSPFv3, BGP, and IS-IS that exchange IPv6 reachability information, allowing the same routing principles to operate across IPv4 and IPv6 deployments.

AI models analyze telemetry from routers, including latency, jitter, and BGP update churn, to flag unusual routing behavior such as route leaks, prefix hijacks, and link saturation faster than threshold-based monitoring tools.

AI tools simulate traffic patterns and recommend updates to routing weights, BGP policies, and traffic-engineering paths. They help service providers reduce latency and balance load across links without manually reconfiguring each router.

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