Architectures With Bus‐Based Switch Fabrics: Case Study—Cisco Catalyst 6500 Series Switches With Supervisor Engine 32

This chapter focuses on the architectures of the Catalyst 6500 Series with Supervisor Engine 32. The Cisco Catalyst 6500 32 Gb/s switching bus allow all the modules connected to it to share the common bandwidth available for both data transmission and data reception. The Supervisor Engine 32 provides connectivity only to the 32 Gb/s shared switching bus and, as a result, supports only line cards that connect to this switching bus. These line card types are the "classic" (also called nonfabric‐enabled) and CEF256‐based line cards. The chapter describes three switching modes (flow‐through mode, compact mode and truncated mode) used by the 32 Gb/s shared switching bus and fabric interface Application‐Specific Integrated Circuits (ASICs) in the CEF256 and CEF720 line cards. It reviews the queue structures and quality of service (QoS) features on the uplink ports of the Supervisor Engine 32, followed by a description of how a packet is forwarded through the Supervisor Engine 32.