The QSFP-DD Series offers up to 400Gbps transmission speeds and features 1-by cages. 4 Tbps aggregate bandwidth in a single switch slot. QSFP-DD electrical interfaces will employ eight lanes that operate up to 25 Gbps NRZ modulation or 50 Gbps PAM4 modulation, providing. QSFP-DD is a new module and cage/connector system similar to current QSFP, but with an additional row of contacts providing for an eight lane electrical interface. 8mm pitch and a dual-mating interface. This. ATGBICS by Approved Tec. Description: QSFP DD Connectors. The core difference between SFP and QSFP is lane count: SFP is a single-lane form factor (1G–25G), while QSFP aggregates 4 (or more) lanes to reach 40G, 100G, 200G and 400G (QSFP-DD).