This chapter briefly introduced some concepts about campus networks, including the hierarchical model, benefits of Layer 3 routing the access, Cisco switches, and some hardware details related to Cisco Catalyst switches. The next chapters of this book go into more detail about specific feature and design elements of the campus network, such as VLANs, spanning tree, and security. The information in this chapter is summarized as follows:
- Flat Layer 2 networks are extremely limited in scale and in most cases will only scale to 10 to 20 end users before adverse conditions may occur.
- Despite its age, the hierarchical model continues to be a key design fundamental of any network design, including campus network designs.
- The hierarchical model consists of an access, distribution, and core layer, thus allowing for scalability and growth of a campus network in a seamless manner.
- The different models of Cisco Catalyst switches provide for a range of capabilities depending on need and placement within the hierarchical model.
- Cisco Catalyst switches leverage CAM for Layer 2 forwarding tables and TCAM for Layer 3 forwarding tables to achieve line-rate performance.
- Cisco Catalyst switches leverage CEF (topology-based switching) for routing, utilizing a distributed hardware forwarding model that is centralized or distributed per line card.