15.12.1 What Is the Difference Between Networking and Internetworking?
- What Is a Computer Network?
- What Is Networking?
- Why Isn't One Large Network Enough?
- What Is Internetworking?
- How Does the Internet Fit Into This Picture?
- What Role Do Routers Play?
- Why Are IP Addresses Needed?
- Can Different Network Technologies Work Together?
- Why Is Layering So Important?
- How Has Internetworking Changed the World?
- What Should You Remember?
Short Answer
Although the terms networking and internetworking are often used interchangeably, they describe two different concepts. Networking refers to connecting computers and other devices within a single network, such as a home, office, school, or factory. Internetworking refers to connecting multiple independent networks together so that information can travel between them. The Internet itself is the world's largest internetwork—a vast collection of millions of smaller networks that communicate using common protocols.
What Is a Computer Network?
A computer network is a collection of devices that exchange information with one another. These devices may include desktop computers, laptops, smartphones, printers, servers, security cameras, industrial controllers, and countless other electronic systems.
The simplest example is a home network. A wireless router allows computers, televisions, gaming consoles, and mobile phones to communicate with one another and share a single Internet connection. Businesses employ similar networks, although on a much larger scale, connecting hundreds or even thousands of devices within offices, factories, hospitals, or university campuses.
Regardless of their size, all computer networks perform the same basic task—they enable devices to exchange digital information.
What Is Networking?
Networking describes the process of creating and operating a single communication network.
Within a Local Area Network (LAN), every connected device communicates using a common set of technologies, typically Ethernet for wired connections and Wi-Fi for wireless devices. These technologies define how information is transmitted, how devices identify one another, and how collisions or transmission errors are managed.
Modern LANs are highly efficient. Ethernet switches learn the location of connected devices and forward information only where it is needed, allowing many conversations to occur simultaneously without interfering with one another.
Most users encounter networking every day without realizing it. Connecting a laptop to home Wi-Fi, printing a document across the office network, or accessing files on a local server are all examples of networking within a single LAN.
Why Isn't One Large Network Enough?
As computer networks grew during the 1970s and 1980s, engineers soon discovered that simply building ever-larger local networks was not a practical solution.
Large Layer-2 networks suffer from several limitations:
- broadcast traffic increases rapidly;
- fault isolation becomes more difficult;
- forwarding tables become larger and more complex;
- performance declines as more devices share the same network.
Perhaps more importantly, local networking technologies such as Ethernet were never designed to connect millions—or billions—of devices spread across different cities, countries, and continents.
A fundamentally different approach was required.
What Is Internetworking?
Internetworking solves this problem by connecting many independent networks into one much larger communication system.
Rather than attempting to create one enormous network, engineers divide communication into many smaller local networks. These networks are then interconnected by routers, which forward information from one network to another.
Each individual network continues to operate independently, using whichever physical technologies are most appropriate. One organization might use Ethernet, another Wi-Fi, another optical fiber, and another satellite communications. Routers allow these diverse networks to exchange information despite their differences.
This concept gives rise to the term internetwork—literally, a network of networks.
How Does the Internet Fit Into This Picture?
The Internet is simply the largest internetwork ever constructed.
Contrary to popular belief, the Internet is not owned or operated by a single organization. Instead, it consists of millions of independently managed networks belonging to:
- Internet Service Providers (ISPs);
- governments;
- universities;
- businesses;
- cloud service providers;
- research organizations; and
- private individuals.
These networks agree to exchange information using the Internet Protocol (IP) and a common family of communication protocols known collectively as the TCP/IP protocol suite.
As a result, information can travel seamlessly between networks that were designed, built, and operated by completely different organizations.
What Role Do Routers Play?
The key device that makes internetworking possible is the router.
Unlike an Ethernet switch, which forwards information only within a local network, a router examines the destination IP address contained within every packet and determines the next network toward which that packet should be forwarded.
Each router performs only one small part of the overall journey. A packet travelling from Australia to Europe may pass through dozens of routers, each forwarding it one step closer to its destination.
This process is remarkably similar to sending a parcel through an international postal system. Individual post offices do not know the complete route to every address in the world. Instead, each forwards the parcel to the next appropriate sorting centre until it eventually reaches the destination.
Routers perform the same function for digital information.
Why Are IP Addresses Needed?
Within a single Ethernet network, devices communicate using Media Access Control (MAC) addresses. These addresses uniquely identify individual network interfaces.
However, MAC addresses provide no information about where a device is located within the wider Internet. They are essentially flat identifiers with no hierarchy.
Internetworking therefore relies upon Internet Protocol (IP) addresses, which contain both:
- a network identifier; and
- a host identifier.
This hierarchical structure allows routers to forward packets efficiently toward the correct destination network without maintaining routes to every individual device connected to the Internet.
Without hierarchical addressing, the Internet could never have grown to its present size.
Can Different Network Technologies Work Together?
One of the greatest strengths of internetworking is that it allows many different communication technologies to coexist.
For example, a single Internet transaction might involve:
- Wi-Fi inside a home;
- Ethernet within an office building;
- optical fiber between cities;
- microwave links across difficult terrain;
- submarine fiber-optic cables between continents; and
- satellite communications serving remote regions.
Although each communication medium operates differently, they all carry Internet Protocol packets. Routers translate between the various local communication technologies while preserving the IP packet itself.
To users, the underlying complexity is completely invisible.
Why Is Layering So Important?
Internetworking succeeds because communication is divided into layers.
Each layer performs a specific task:
- the Physical Layer transmits signals;
- the Data Link Layer delivers frames across a single network;
- the Network Layer forwards packets between networks; and
- the Transport Layer delivers information to the correct application.
This layered architecture allows engineers to improve one part of the communication system without redesigning every other part.
For example, Wi-Fi has evolved through numerous generations, and optical fiber continues to become faster, yet Internet applications continue to function because the higher protocol layers remain largely unchanged.
This modular design has been one of the principal reasons for the extraordinary longevity and success of the Internet.
How Has Internetworking Changed the World?
Internetworking transformed computing from isolated systems into a global communications infrastructure.
Instead of merely connecting computers within individual buildings, internetworking made it possible to exchange information between organizations, countries, and continents.
Today, billions of people rely upon internetworking every day for:
- web browsing;
- electronic mail;
- video conferencing;
- online banking;
- cloud computing;
- media streaming;
- industrial automation;
- scientific collaboration; and
- the Internet of Things (IoT).
Few users think about the thousands of routers, optical links, wireless systems, and communication protocols involved each time they open a web page or send a message. Yet all of these technologies work together to provide what appears to be a single, seamless communication system.
What Should You Remember?
Networking and internetworking are closely related but fundamentally different concepts.
Networking concerns communication within a single network using technologies such as Ethernet and Wi-Fi. Internetworking extends communication beyond the boundaries of individual networks by using routers, logical IP addressing, and common Internet protocols.
The Internet is therefore not one enormous network. It is a carefully coordinated collection of millions of independent networks that cooperate to exchange information.
This distinction between networking and internetworking represents one of the most important architectural ideas in modern digital communications. It is this simple concept—a network of networks—that has enabled the Internet to grow into the largest communication system ever built.
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