At the center of the Cisco Nexus 4001I is the unified switch application-specific integrated circuit (ASIC), a new, purpose-built, high-performance, line-rate switch ASIC that delivers extremely low and consistent latency across all packet sizes independent of the configured networking features. The unified switch ASIC supports standard Ethernet as well as Priority Flow Control (PFC) and Enhanced Transmission Selection, required for lossless Ethernet transmission. LAN and SAN networking protocols are delivered through Cisco® NX-OS Software, the industry''s first modular, fault-tolerant, highly available operating system designed specifically to support unified fabric data center networks. Using the combination of the unified switch ASIC and Cisco NX-OS, the Cisco Nexus 4001I extends the benefits of the Cisco Nexus Family of data center switches to blade servers: the fastest growing segment of the server market.