1.6 Compare and contrast network topologies, architectures, and types
Traffic Flow
📘CompTIA Network+ (N10-009)
Traffic Flows – North-South
In networking, traffic flow describes the direction that data moves through a network. Understanding traffic flows is important for designing secure, efficient networks, and it’s a key topic for the CompTIA Network+ exam.
There are two main types of traffic flows:
- North-South
- East-West (we’ll mention briefly for context)
Here, we focus on North-South.
Definition
North-South traffic is data moving between a local network (internal network) and an external network, usually the Internet.
- Think of North as “outward” toward the external network.
- Think of South as “inward” from the external network into your internal network.
Key point: North-South traffic always moves into or out of a network, not within the network itself.
Direction and Flow
- Inbound traffic (North → South): Data coming from outside (like the Internet) into your internal network.
- Example: A user inside your company opening a website or downloading a file from the Internet.
- Outbound traffic (South → North): Data going from inside your network out to external networks.
- Example: Your internal server sending emails to clients outside your network.
Where North-South Traffic Happens
North-South traffic usually passes through network devices that control access and security:
- Firewalls – Filter traffic coming in and out.
- Routers – Direct traffic between internal and external networks.
- Load balancers – Distribute incoming traffic to servers efficiently.
Why North-South Traffic Matters
- Security
- This is the main path hackers use to try to access your network.
- Firewalls and intrusion detection systems monitor this flow closely.
- Bandwidth Management
- Because all inbound and outbound traffic passes through the network edge, it can become a bottleneck.
- Network engineers monitor and optimize this flow to ensure smooth Internet access.
- Policy Enforcement
- Security rules (like blocking malicious websites or controlling which servers can communicate outside) are applied to North-South traffic.
Examples in IT Environments
- Corporate Email:
- Outbound: Your employees send emails to clients outside your network.
- Inbound: Clients send emails to your internal servers.
- Web Hosting:
- Outbound: Internal server sending data (like web pages) to Internet users.
- Inbound: Requests from Internet users trying to access your website.
- Remote Work / VPN:
- North-South traffic is used when remote employees access company resources from outside.
Important Notes for the Exam
- North-South = External ↔ Internal traffic
- Flows through firewalls, routers, and load balancers
- Focus on security and monitoring because most attacks come via North-South traffic
- Often contrasted with East-West traffic, which stays within the network (internal server-to-server communication)
✅ Exam Tip:
If a question asks:
“Which type of traffic is moving between internal servers and the Internet?”
The correct answer is North-South traffic.
