The Arista QSFP-40G-UNIV is a QSFP 40GbE transceiver with a duplex LC connector that can be used with both multi-mode (MM) and single-mode (SM) fiber. It has 4 channels of 10G multiplexed inside the module to transmit and receive an aggregate 40G signal over 2 strands of fiber. Both use the same QSFP+ form factor and both deliver 40 Gbps full-duplex—but they're built for very different jobs. The following figure shows a brief. The Cisco ® 40GBASE QSFP (Quad Small Form-Factor Pluggable) portfolio offers customers a wide variety of high-density and low-power 40 Gigabit Ethernet connectivity options for data center, high-performance computing 00networks, enterprise core and distribution layers, and service provider. Singlemode QSFP+ and multimode QSFP+, here, refer to QSFP+ optical modules that work on different types of optical fiber, i. Dual fiber modules use two fibers. They are easier to set up and give steady communication. They use a thin fiber. Key insight: Above 25G, nearly all LC-based transceivers are single-mode, because multimode (MMF) reaches drop sharply at high speeds. SFP covers 1G-100G in compact form factors. These modules also come in SMF/MMF variants, but they are not part of the "SFP family"-they simply serve higher-density.