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Understanding Network Architectures and Models

Aug 8, 2024

Network Architectures Lecture Notes

Three-Tier Architecture

  1. Core Layer

    • Center of the network
    • Major services located here: web servers, database servers, name servers, etc.
    • Central access point for organization

  2. Distribution Layer

    • Midpoint between end users and core
    • Manages communication and traffic control
    • Provides redundancy

  3. Access Layer

    • Where users are located
    • Access switches close to users

Analogy: City Layout

  • Core: Downtown with office buildings
  • Distribution: Highways connecting home to downtown
  • Access: Local neighborhoods

Network Diagram

  • Users → Access Switches → Distribution Switches → Core Switches
  • Redundancy: Multiple distribution switches
  • Larger Networks: Access switches on each floor/building

Software-Defined Networking (SDN)

  1. Data Plane

    • Infrastructure layer
    • Handles forwarding: network frames, packets, routing, encryption, NAT

  2. Control Plane

    • Manages routing tables, switching tables, NAT tables

  3. Management Plane

    • Application layer
    • Network administrators manage devices
    • Management interfaces: SSH console, SNMP, API calls

Virtualization

  • SDN fits with cloud-based architectures
  • Break physical components into functional planes
  • Example: Physical switch split into data, control, and management planes

Spine and Leaf Architecture

  • Leaf Switches: Connected to services
  • Spine Switches: Connected to all leaf switches
  • Connections: Leaf to spine, no direct leaf-to-leaf or spine-to-spine
  • Redundancy: Simple cabling, efficient communication
  • Scaling: Adding racks increases cost due to additional spine switch connections

Terms

  • East-West Traffic: Within same data center (e.g., image server to web server)
  • North-South Traffic: Exiting data center (requires different security)

Data Center Deployment Models

  1. Branch Offices

    • Local devices: switches, routers, firewalls, client devices

  2. On-Premises Data Centers

    • In-house management: cooling, electrical systems, monitoring

  3. Co-Location Centers

    • Third-party data center
    • Multiple companies within same facility
    • Secure access: cages, locked doors
    • Third-party responsible for monitoring and security

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