The VIP4 is a highly configurable, RISC-based, intelligent interface processor. Up to two separate port adapters (PAs) can be configured on each VIP4. PAs provide the media-specific interfaces for the VIPs, enabling the VIP4 configuration to be optimized in terms of price, performance, and density. More than 50 media-specific LAN and WAN PAs are supported, including Fast Ethernet, T1/E1, High-Speed Serial Interface (HSSI), T3/E3, T3/E3 ATM, multichannel T1/E1, multichannel T3/E3, OC-3 ATM, packet over SONET (POS), and OC-12 ATM.
The VIP4 greatly increases the switching performance of the Cisco 7500 series and serves as an ideal platform for new, higher-speed, higher-density LAN and WAN interfaces. On the Cisco 7500 series, VIP4 distributed switching scales system performance to over two million packets per second (pps). In addition, the VIP4 features Single-Error-Correction, Double-Error-Detection Code (SECDED) logic, detecting and correcting single event upsets within a data word. This enables greater system resiliency and continued system availability in the presence of a single-event parity upset.
A key VIP4 feature is its ability to receive and execute on route information provided by the master Route Switch Processor (RSP). Based on this route data, a VIP4 can make its own Layer 3 switching decisions, providing a scalable, distributed switching architecture, called distributed switching (DSW). Further, DSW scales packet-processing throughput of a VIP4-equipped router, and resources for route policy and administration are increased by off-loading the central processor of packet-handling tasks.
The VIP4-50 offers support for distributed switching and distributed services. Powered by a 250-MHz RM5000, it provides large program memory to accommodate Layer 3 route information from the RSP for autonomous switching decisions, and large packet memory capacity necessary for distributed IP services. In addition, the VIP4-50 runs a subset of Cisco IOS software to provide support for enhanced network services such as distributed queuing and software-based encryption and compression.