Switch/Router Architectures

13Case Study: Quality of Service Processing in the Cisco Catalyst 6000 and 6500 Series Switches

13.1 Introduction

The key QoS functions in the Catalyst 6000/6500 family of switch/routers requiring real-time processing are implemented in hardware. These QoS-related hardware components are implemented on Catalyst 6000/6500 modules such as the Policy Feature Card (PFC) and the port ASICs on the line cards. This chapter describes the QoS capabilities of the PFC and the switch/router port ASICs on the line cards [CISCUQSC06,CISCUQSC09].

The Multilayer Switch Feature Card (MSFC) supports some QoS functions such as control plane policing and other rate-limiting functions for control and management traffic. These special QoS functions are not discussed in this chapter. Detailed descriptions of the PFC and MSFC are given in Chapters 7 and 9.

13.2 Policy Feature Card (PFC)

The PFC1 is a daughter card that is supported only on the Supervisor Engine 1A of the Catalyst 6000/6500 family. The PFC2 is an improved design of the PFC1 and is supported on Supervisor Engine 2. PFC1 and PFC2 are the primary modules on which the hardware-based QoS functions are implemented for Supervisor Engine 1 and 2, respectively. Supervisor Engine 32 supports the PFC3B and MSFC2a as a default configuration. Supervisor Engines 720, 720-3B, and 720-3BXL all support PFC3 and MSFC3. The newer generations of the PFC support more advanced QoS functions than the older ones.

13.2.1 Policing in the PFC

In addition ...