Module Review

In this module, we climbed into the virtualized stratosphere to explore the foundations of modern cloud networks.

1. Key Takeaways

  • Virtual Private Cloud (VPC): Isolated network environments in public clouds with subnets, route tables, and gateways.
  • SDN (Software Defined Networking): The architectural shift of separating the Control Plane (centralized brain) from the Data Plane (forwarding hardware).
  • NFV (Network Function Virtualization): Replacing expensive, proprietary hardware appliances with virtualized software (VNFs) running on standard servers.
  • Load Balancing: Distributing traffic effectively at Layer 4 (Transport) or Layer 7 (Application) using strategies like Round Robin or Least Connections.
  • CDN (Content Delivery Network): Reducing global latency by caching static content at Edge Locations geographically close to users.

2. Flashcards

What is the difference between a Security Group and a NACL?
A Security Group acts at the Instance level and is stateful; a NACL acts at the Subnet level and is stateless.
In SDN, which plane makes forwarding decisions?
The Control Plane, which is typically centralized in an SDN Controller.
What is a VNF in the context of NFV?
A Virtual Network Function: a software version of a network appliance like a firewall or load balancer.
Which load balancing algorithm provides Session Stickiness?
IP Hashing, which ensures a user with a specific IP always hits the same server.

3. Cheat Sheet

Concept Description Key Component
VPC Isolated cloud network Subnets, IGW, Route Tables
SDN Separation of Control/Data Controller, OpenFlow
NFV Software-based network appliances VNF, Hypervisor, MANO
L4 Balancer Routes by IP/Port Network Load Balancer (NLB)
L7 Balancer Routes by HTTP/Headers Application Load Balancer (ALB)
CDN Distributed edge caching Origin Server, PoP (Edge)

4. Quick Revision

  • VPC Peering: Connects two VPCs using private IPs; not transitive.
  • NAT Gateway: Allows private subnets to download from the internet without exposing instances to incoming traffic.
  • SDN Controller: The central “brain” that programs flow tables in hardware switches.
  • Service Chaining: A benefit of NFV, allowing network traffic to be steered through multiple VNFs sequentially.
  • Health Checks: Necessary for load balancers to ensure they don’t route traffic to dead servers.

5. Next Steps

We have reached the home stretch! In the final module, we focus on the “Survival Skills” of a network engineer: Reliability, Quality of Service (QoS), and Monitoring/Troubleshooting.