Cisco Catalyst 4500 Series switches offers an extensive line of modules that support numerous speeds and physical media combinations. These line cards are functionally transparent; all the packet processing, queuing, buffering, and QoS occur in the supervisor engine. To that end, both classic and E-Series line cards acquire the features and capabilities of the installed supervisor engine. For example, a classic line card previously deployed with a classic supervisor engine using 4 queues per port will automatically have capability for 8 queues per port (first half CY2008) if redeployed with a Supervisor Engine 6-E. This architecture enables customers to easily upgrade all Ethernet line cards on their Cisco Catalyst 4500 Series systems to higher-layer switching functions by adding a new supervisor engine. The simple design of the line cards results in a very high mean time between failures (MTBF), helping ensure high availability for a single connection to an end user.

The Cisco Catalyst 4500 Series is a centralized architecture that is designed to provide dedicated wire-speed bandwidth to each line-card slot within the chassis. Each line card has a dedicated bandwidth to the supervisor engine for packet processing. All network data that flows into the Cisco Catalyst 4500 Series through the various line cards goes through the supervisor engine for processing, even in single-slot port-to-port communications. All line cards have some per slot bandwidth that allows network administrators to design a system that offers full dedicated bandwidth-to-server and switch-to-switch applications and still provide high performance over subscribed gigabit to the desktop.
A modular centralized design allows customers to use their investment in high-performance line cards across the entire line of Cisco Catalyst 4500 Series chassis and supervisor engines. For example, line cards that shipped with the original Cisco Catalyst 4003 Switch in 1999 will work in the Cisco Catalyst 4500 E-Series chassis. Because of the centralized architecture of the Cisco Catalyst 4500, all line cards deployed in a chassis benefit from the enhanced features the supervisor engine provides including Security, QoS, Layer 2/3/4 routing, and hardware-based IPv6.