Key Concepts in Networking and Software-Defined Networking (SDN)

Physical Isolation in Networking

• Objective: Preventing attackers from moving between devices.
  • Example: Air gap between switch A and switch B to prevent access from one to the other.
• Scenario: If devices on switch A need to communicate with devices on switch B:
  • Requires some form of connectivity (direct connection, another switch, or a router).
• Use Cases:
  • Web servers in one rack, database servers in another with air gap isolation.
  • Managed Service Providers using physical isolation for customers to provide security by placing customers on separate switches.
  • Limitation: Requires one physical switch per customer, which doesn’t scale well.

VLANs (Virtual Local Area Networks)

• Function: Allows segmentation on the same physical switch:
  • Interfaces are configured to belong to different VLANs.
  • VLANs cannot directly communicate with each other, mimicking the effect of separate physical switches.
  • Simplifies network design and reduces the number of physical switches needed.

Planes of Operation in SDN

• Data Plane:
  • Handles actual data forwarding between devices.
  • Involves Network Address Translation (NAT), encryption, trunking, etc.
• Control Plane:
  • Manages routing tables and updates, dictates data flow.
  • Includes dynamic routing updates, NAT tables.
• Management Plane:
  • Where configuration changes are made (via SSH, etc.).
  • Dictates control plane management which in turn influences the data plane.

SDN (Software-Defined Networking)

• Concept: Breaking down physical operations into software for cloud-based applications.
• Infrastructure Layer Components:
  • Data Plane: Physical aspect (interfaces on the switch).
  • Control Plane: Handles necessary lookups and translations.
  • Management Plane: Interfaces for changing configurations.
• Cloud Integration:
  • Allows dynamic creation of infrastructure (e.g., adding firewalls via SDN).
  • Simplifies configuration and deployment of network resources.

Cloud-Based Architecture Example

• Components:
  • Internet connection, load balancer, web servers, database server.
  • Firewalls can be added dynamically to control traffic between components.
• Technology: Enabled through Software-Defined Networking which allows easy and quick infrastructure adjustments and deployments.