Chapter 1 - section 1.6 - Compare and contrast network topologies, architectures, and types.

section 1.6

Objective – Network Topologies and Traffic Flows

• Mesh
• Hybrid
• Star / Hub-and-Spoke
• Spine and Leaf
• Point-to-Point
• Three-Tier Hierarchical Model
▸ Core
▸ Distribution
▸ Access
• Collapsed Core
• Traffic Flows
▸ North-South
▸ East-West

Topology – Mesh

• Multiple redundant connections between devices
• High availability and fault tolerance
• Expensive and complex
• Partial mesh is most common (N10-009)
• Used in WANs and wireless mesh networks

Topology – Hybrid

• Combination of two or more topologies
• Most real-world enterprise networks
• Flexible and scalable
• Inherits advantages and disadvantages of each topology

Topology – Star / Hub-and-Spoke

• All devices connect to a central device
• Easy to manage and troubleshoot
• Central device is a single point of failure
• Common in LANs and WAN branch networks

Topology – Spine and Leaf

• Data center architecture
• Leaf switches connect to endpoints
• Spine switches interconnect all leaf switches
• Predictable latency and high scalability
• Optimized for east-west traffic (exam critical)

Topology – Point-to-Point

• Direct connection between two devices
• Simple and fast
• Common for WAN links
• No redundancy unless duplicated

Architecture – Three-Tier Hierarchical Model

• Traditional enterprise network design
• Improves scalability and manageability
• Separates network roles for performance and security

Three-Tier Layer – Core

• High-speed backbone layer
• Focuses on fast packet forwarding
• No ACLs or packet filtering (exam critical)
• Connects distribution layers

Three-Tier Layer – Distribution

• Policy enforcement layer
• Routing, ACLs, and QoS applied
• Aggregates access layer switches
• Acts as boundary between core and access

Three-Tier Layer – Access

• End-user device connectivity
• Switches for PCs, printers, APs
• VLAN assignment and port security
• Closest layer to users

Architecture – Collapsed Core

• Core and distribution layers combined
• Used in small-to-medium networks
• Lower cost and simpler design
• Less scalable than three-tier model

Traffic Flow – North-South

• Traffic entering or leaving the network
• Client-to-server or internet traffic
• Common in traditional data centers
• Often passes through firewalls

Traffic Flow – East-West

• Traffic within the data center
• Server-to-server or VM-to-VM traffic
• Common in cloud and virtualized environments
• Spine-leaf architecture optimized for this

N10-009 Sample Questions – Network Topologies

• Q: Which topology provides the highest redundancy?
▸ A: Mesh
• Q: Which architecture is optimized for east-west traffic?
▸ A: Spine and leaf
• Q: Which layer should NOT perform packet filtering?
▸ A: Core layer
• Q: Which traffic type is internal to a data center?
▸ A: East-west