Network Services
Network Services
🎯 Exam Objectives
Track your learning progress! Click each objective as you master it:
- Differentiate VLAN, VXLAN, and GENEVE technologies
- Understand SDN architecture (Control Plane vs. Data Plane)
- Compare VPC designs (Hub-and-Spoke, VPC Peering)
- Explain Client NAT vs. Cloud NAT implementations
- Understand Transit Gateways and Content Delivery Networks (CDNs)
🔀 7.19 & 7.20 VLAN Evolution
Traditional Layer 3 segmentation requires physical proximity. Virtual LANs (VLANs) solved this by using Layer 2 switch ports and software rules to isolate traffic, tagging it with a VLAN-specific identifier. However, as cloud networks grew, new technologies were needed.
Virtual Local Area Network (VLAN)
- Operates at Layer 2
- Limited to 4,094 network segments
- Isolates traffic within switches using tags (e.g., IEEE 802.1Q)
- Requires a router to communicate between different VLANs
Virtual Extensible LAN (VXLAN)
- Supports ~16 million network segments
- Encapsulates Layer 2 headers in a Layer 3 UDP header
- Provides tunneling services between VXLANs
- Ideal for "VLAN stretching" between on-premises and cloud networks
Generic Network Virtualization Encapsulation (GENEVE)
- A universal standard for defining data format
- Resolves incompatibility between VXLAN (AWS), NVGRE (Azure), and STT
- Essential for multi-cloud deployments
- Uses standard network devices without specialized hardware
🧠 7.21 Software-Defined Networking (SDN)
Traditional networks are decentralized, requiring per-device configuration. SDN centralizes administration by decoupling the network into two distinct planes, managed by a central controller using policies.
🎛️ Control Plane (Centralized)
Programmable layer that dictates policies, routing rules, and configurations for the entire network. Managed by a central SDN Controller.
Forwards/Filters
Routes IP/MAC
Distributes Traffic
The Data Plane handles the actual packet forwarding based on instructions from the Control Plane.
☁️ 7.22 & 7.23 Virtual Private Clouds (VPCs)
VPCs implement a single-tenant structure within a CSP's multi-tenant environment, providing enhanced isolation, security, and VPN connectivity while retaining cloud benefits like scalability and pay-per-use.
VPC Design Models
Click on a design to explore its use cases:
A central "hub" network hosts common services (e.g., Active Directory, DNS). "Spoke" networks attach to the hub, not to each other.
- Isolating workloads (Dev, Test, Prod)
- Centralized traffic management and analysis
- Delegating administrative tasks per spoke
Provides a direct, fast network connection between two VPCs, making them appear as a single network to consumers.
- Connecting spoke networks to the hub
- Sharing resources across different cloud accounts
- Low-latency data access without extra virtual devices
🔄 7.24 Network Address Translation (NAT) in VPCs
NAT maps internal IP addresses to public ones, allowing communication across the Internet without exposing internal network structures.
💻 Client NAT
- Maps multiple internal client IPs to a single external public IP.
- Hides internal IP addresses from the Internet.
- Tracks sessions in tables to route return traffic to the correct internal user.
- Commonly used for secure Internet browsing from corporate networks.
☁️ Cloud NAT
- Allows virtualized cloud resources (VMs in VPCs) to access the Internet without public IPs.
- Maps Source NAT and Destination NAT connections.
- Useful for CDN connectivity, data replication, or AI/ML resource access.
- Examples: AWS NAT Gateways, Azure NAT Gateway, GCP Cloud NAT.
🌉 7.25 Transit Gateway in the Cloud
As cloud deployments scale, managing multiple point-to-point connections becomes complex. A Transit Gateway acts as a central cloud router (hub) to manage and direct traffic between various network areas.
Note: CSPs typically charge an hourly rate for transit gateway implementations, accessible via console, CLI, or APIs.
🚀 7.26 Content Delivery Networks (CDNs)
CDNs provide high availability and performance by caching commonly accessed information (web apps, scripts, multimedia) geographically near the consumers at Point of Presence (PoP) locations.
Interactive CDN Simulation
Click the button to deploy CDN edge nodes and see how latency is reduced for global users.