15 LAN architectures

This chapter covers

  • Star and mesh topologies
  • Two- and three-tier campus LANs
  • The advantages of spine-leaf architecture in data center networks
  • Small office/home office networks

We have delved into the details of protocols like IPv4 and IPv6, Ethernet, Spanning Tree Protocol, and many others in previous chapters of this volume and volume 1. Now it’s time to zoom out. Instead of focusing on individual technologies, let’s take a holistic view of real-world network architectures—the blueprints for how computer networks are designed and built.

Although there are standard best practices in network design, many factors such as budget, scale, and specific needs influence the “right” approach; there are few universal correct answers to questions of network design. In the beginning stages of your networking career, you probably won’t be designing networks. However, to configure and troubleshoot networks, understanding the architectural principles behind them is essential.

This chapter and the following two align with CCNA exam topic 1.2: Describe characteristics of network topology architectures. This chapter focuses on various types of LANs, from data centers to home offices. Specifically, we will cover the following subtopics:

  • 1.2.a Two-tier
  • 1.2.b Three-tier
  • 1.2.c Spine-leaf
  • 1.2.e Small office/home office (SOHO)

15.1 Common topologies: Star and mesh

15.2 Campus LAN architectures

15.2.1 Two-tier (collapsed core) LAN architecture

15.2.2 Three-tier LAN architecture

15.3 Data center architectures: spine-leaf

15.3.1 Traditional data center networks

15.3.2 Spine-leaf architecture

15.4 SOHO networks