31.2 CISCO CATALYST 6000/6500 SWITCH - SUPERVISOR 1A

Supervisor 1A with no PFC

The simplest configuration option available for the Catalyst 6000 is just the Supervisor 1 module with no policy feature card (PFC) or MSFC. In this configuration, the switch is essentially a Layer 2 switch and possesses no Layer 3 switching or classification capabilities. A Supervisor 1A can provide a Layer 2 switch up to 15 million packets per second (Mpps).   

 Supervisor 1A with PFC-1

 The next option available for the Catalyst 6000/6500 is the Supervisor 1 module with a policy feature card (PFC-1) installed. The PFC-1 enables Layer 3 and 4 classification for QoS classification and security ACL filtering; however, L3 switching is not supported unless an MSFC is added to provide route processor functions. The Supervisor 1A with PFC-1 is capable of processing frames through the QoS and ACL engines without degrading Layer 2 switching performance, at speeds of up to 15 Mpps.

Fig 31.1.1 will show the basic architecture of Supervisor 1A with PFC-1.

Fig 31.2.1

As you can see, the the Supervisor 1A contains the basic Layer 2 engine that references the local bridge table for determining the egress port for switching decisions. The PFC contains a Layer 3 engine, flow cache, ACL engine, and ACL table. In this configuration, the PFC is not used for L3 switching, because no route processor (provided by an MSFC) is installed that provides the required next hop information. However, the PFC can be used for Layer 3/4 QoS classification and ACL filtering; the ACL engine is responsible for providing these functions. The ACL table is stored in ternary content addressable memory (TCAM), which stores ACL information in a format that can be referenced very quickly by the ACL engine. When a packet arrives that requires ACL filtering, while the L2 engine determines the forwarding decision to be made based upon the information contained within the L2 bridge table, at the same time, the ACL engine

determines whether or not the packet is permitted or denied. Because the L2 lookup and ACL lookup occur in parallel, applying ACLs or QoS classification to traffic does not affect the forwarding rate of the switch (15 Mpps).