Case Study: Quality of Service Processing in The Cisco Catalyst 6000 and 6500 Series Switches
James Aweya · 2018
The key quality of service (QoS) functions in the Catalyst 6000/6500 family of switch/routers requiring real-time processing is 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. 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. The Distributed Forwarding Card (DFC) allows fabric-enabled and fabric-only line cards to perform packet forwarding and QoS processing locally without direct MSFC intervention. To facilitate the application of QoS services to traffic passing through the switch/router, mechanisms to tag or prioritize IP packets or Ethernet frames are required. The chapter also describes the various QoS operations that are applied to a packet as it transits the switch/router.