CCNA 3-Tier Network Design Simulation

Typical devices: Layer 2 switches , or Layer 3-capable access switches in a Routed Access design.
Main functions: access ports, trunk uplinks, VLANs, voice VLAN, PoE, Port Security, 802.1X, DHCP Snooping, and Dynamic ARP Inspection.
Edge loop control: use PortFast + BPDU Guard on user-facing ports; Layer 2 uplinks need STP/MST or EtherChannel.
Practical design: access switches are often dual-homed to two Distribution switches. One uplink may be blocked if the topology remains Layer 2.

3-Tier Architecture Overview

In enterprise networks, layered design improves scalability, fault isolation, and policy control. This lab shows the Campus 3-Tier model: Access, Distribution, and Core.

Select a layer to inspect its role. Example Data Path shows one possible path only; real forwarding depends on STP, FHRP, routing metrics, ECMP, and vendor design.

Practical note: redundancy does not mean every link forwards at the same time. With Layer 2 access, STP/MST may block some uplinks. With Routed Access, routing and ECMP handle redundancy.

Server/App: in larger networks, applications usually sit in a Data Center or a dedicated services block. Here it is simplified as a traffic destination.