400GBASESR8

400GBASE-SR8 is an Ethernet physical layer standard defined by the IEEE 802.3bs and 802.3cd standards. It is designed for short-reach optical communication, typically within data centers. The SR8 designation indicates that it operates over multimode fiber and utilizes eight optical lanes. Each lane transmits and receives data at 50 gigabits per second (Gbps), resulting in a total bidirectional bandwidth of 400 Gbps. This is achieved through the use of PAM4 (Pulse Amplitude Modulation with 4 levels) signaling, which allows each symbol to carry two bits of data.

400GBASE-SR8 uses MPO (Multi-fiber Push-On) connectors to accommodate the multiple fiber strands required. Specifically, it employs 16 optical fibers in total: eight for transmitting and eight for receiving. The maximum transmission distance for 400GBASE-SR8 is limited to 100 meters over OM3 multimode fiber and 150 meters over OM4 multimode fiber. This makes it suitable for interconnections between switches, servers, and other networking equipment within a single rack or across short distances within a data center. Its high bandwidth and short-reach capabilities make it a key technology for supporting the increasing demands of cloud computing, artificial intelligence, and high-performance computing.