Chapter 6. Layer 3 Switching
In the previous chapter, you were introduced to the concept of Layer 3 switching on the Catalyst 3550; however, the focus of the chapter was more on the fundamental concept of inter-VLAN routing and routing protocols rather than focusing specifically on Layer 3 switching. In this chapter, you learn about Layer 3 switching in detail and how to configure Layer 3 switching on the flagship of the Cisco Catalyst product family, the Catalyst 6000/6500.
Although this chapter shows you how to configure Layer 3 switching on the Catalyst 6000/6500, the same concepts and configurations discussed in scenarios based around Layer 3 switching using Cisco Express Forwarding (CEF) can be applied to other CEF-based Cisco Catalyst Layer 3 switching platforms, such as the Catalyst 3550 and Catalyst 4000/4500 Supervisor 3/4 engines.
This chapter looks initially at software-only versus hardware-assisted Layer 3 (L3) switching (routing), examining the architectures used by each, which enables you to understand the limitations of software-based L3 switching and the advantages of hardware-based L3 switching. You learn about Multilayer switching (MLS), which represents an older Layer 3 switching technology used on older Catalyst switches and then learn about CEF-based Layer 3 switching, which is the current Layer 3 switching technology used on all next-generation Cisco Layer 3 switches (e.g., Catalyst 3550, Catalyst 4000/4500 Supervisor 3/4, and Catalyst 6000/6500 Supervisor 2 with PFC-2 + MSFC-2). You also learn about the architecture of the Catalyst 6000/6500, which represents the flagship of the Cisco Catalyst switching family.
Finally, the scenarios for this chapter are presented, which focus initially on MLS and then focus on the Catalyst 6000/6500 and how to configure CEF-based L3 switching on these switches. You also learn how to convert a Catalyst 6000/6500 from hybrid mode (CatOS) to native Cisco IOS, which is the future operating system for all Catalyst switches. After introductory material, the following scenarios are presented in this chapter: