What is Network Traffic?
Network traffic is the flow of data packets across computer networks — from local area networks (LANs) in offices and homes to the global internet. Every action online generates network traffic: loading a webpage, sending an email, streaming a video, or making a video call.
Unlike physical traffic which moves in continuous streams, network traffic is packet-switched — data is broken into small discrete units (packets), each routed independently across the network and reassembled at the destination. This architecture makes the internet extraordinarily resilient: if one route fails, packets find another.
Key insight: The internet was designed to survive nuclear attack. Its packet-switched, decentralised architecture means there is no single point of failure — traffic routes around damage automatically. This design decision from the 1960s still governs how every packet travels today.
Live Packet Flow Visualizer
The visualizer below simulates how different types of network traffic behave. Switch between protocols to see how packet size, frequency, and routing patterns differ across use cases.
The OSI Model — 7 Layers of Network Traffic
The Open Systems Interconnection model divides network communication into seven abstraction layers. Each layer handles a specific aspect of data transmission — from the physical electrical signals in cables to the application protocols users interact with.
Understanding the OSI model is fundamental to diagnosing network problems: a packet loss issue lives at Layer 3, a TLS certificate error at Layer 6, a slow database query at Layer 7. Traffic engineers diagnose by layer.
How TCP Establishes Traffic Flow
Before any data flows between two hosts over TCP, they must complete a three-way handshake — a choreographed exchange that establishes a reliable, ordered connection. Every webpage load, file download, and API call begins with this ritual.
BGP — The Internet's Traffic Router
Border Gateway Protocol (BGP) is the routing protocol that makes the internet work. It enables the 75,000+ autonomous systems (AS) — networks operated by ISPs, cloud providers, enterprises, and universities — to exchange reachability information and route traffic between them.
BGP is a path vector protocol: each AS advertises the paths it knows to reach every IP prefix, and routers select the best path based on a complex set of attributes including path length, origin, and local preference. When a major BGP misconfiguration occurs, large portions of internet traffic can be misdirected — as happened with the Facebook outage of 2021.
Latency vs Bandwidth
The two most commonly confused network metrics are latency and bandwidth — and confusing them leads to misdiagnosed problems and wasted investment. They measure fundamentally different things.
Bandwidth is the maximum volume of data that can flow per second — the width of the pipe. Latency is the time delay for a packet to travel from source to destination — how quickly the pipe responds. A high-bandwidth link with high latency feels slow for interactive use. A low-bandwidth link with low latency feels responsive.
Core Network Protocols
Network traffic is governed by protocols — agreed standards that define how packets are formatted, addressed, transmitted, and received. The internet runs on a layered stack of protocols, each handling a specific aspect of communication.
| Protocol | Layer | Purpose | Traffic type |
|---|---|---|---|
| TCP | Transport | Reliable, ordered delivery with error recovery and flow control | Connection |
| UDP | Transport | Fast, connectionless delivery — no guarantees, low overhead | Streaming |
| QUIC | Transport | Modern replacement for TCP+TLS, used by HTTP/3 for lower latency | Modern web |
| IPv4/IPv6 | Network | Logical addressing and routing of packets across networks | All traffic |
| BGP | Network | Inter-autonomous system routing — the internet's backbone protocol | Routing |
| DNS | Application | Translates domain names to IP addresses — every web request begins here | Resolution |
| HTTP/3 | Application | Latest web protocol running over QUIC, dramatically faster than HTTP/1.1 | Web |
| TLS 1.3 | Presentation | Encryption and authentication for secure traffic — HTTPS, SMTPS, FTPS | Secure |
| OSPF | Network | Interior gateway protocol for routing within a single autonomous system | Routing |
| ICMP | Network | Diagnostic protocol — ping, traceroute, and error messages live here | Diagnostic |
The Global Traffic Mix
Not all internet traffic is equal. Video streaming now dominates global bandwidth consumption, having grown from negligible in 2005 to over 60% of all internet traffic today. Understanding the composition of network traffic shapes everything from ISP infrastructure investment to CDN architecture.
Global internet traffic composition by bandwidth consumption. Source: Sandvine Global Internet Phenomena Report 2024.