Selecting a 25GbE Adapter Without Losing the Security Suffix
Exact AN/AS distinction and legacy ACAT comparison. No measured latency or customer-outcome claims.
Selecting a 25GbE Adapter Without Losing the Security Suffix
Two adapters can have the same connector, line rate and board dimensions while meeting different platform-security requirements. For a replacement or expansion, preserve the complete ordering suffix in the technical specification and receiving checklist.
Compare the right two variants
MCX631102AN-ADAT and MCX631102AS-ADAT are ConnectX-6 Lx cards with two SFP28 ports, a PCIe 4 x8 host connection and Ethernet rates through 25 Gb/s. Their exact ordering entries distinguish secure boot: AN disables it and AS enables it. Both disable hardware crypto. A request for “dual-port 25G ConnectX-6 Lx” is therefore incomplete when the platform has a secure-boot requirement.
Treat secure boot and traffic crypto as separate fields. The presence of one does not imply the other, and a connector photograph cannot establish either. Record the full model and expected security configuration alongside the server’s requirements. Where a card is OEM-labelled, preserve its actual identity and PSID rather than assuming a retail-family firmware image is appropriate.
Do not infer speed from the cage
The MCX631102 variants are specified for dual SFP28 1/10/25 GbE. The ConnectX-6 Lx family also contains a different single-QSFP28 50 GbE design. That broader family capability is useful context, but it is not an additional enabled rate for the requested dual-port model. Apply the same rule to a switch or transceiver: match its exact supported configuration rather than its connector name alone.
Budget for the deployed interconnect
The model-group table supplies separate power figures for PCIe generations and cable conditions. Use the intended passive or active interconnect condition and review the required airflow direction. A passively cooled adapter still depends on server airflow. Evaluate the actual chassis, inlet conditions and chosen optical module together instead of treating a typical board-power number as a complete thermal design.
Keep a legacy alternative in its proper context
MCX4121A-ACAT offers dual-SFP28 25 GbE over PCIe 3 x8, but belongs to an end-of-life ConnectX-4 Lx line. It is not an automatic substitute for either newer suffix. Its introduction also distinguishes secure-firmware and UEFI variants separately. A legacy replacement decision should check software support, exact features, bracket fit and unit health before considering nominal rate equivalence.
The result should be a concise acceptance record: full order code, security state, host link, firmware identity, both port tests, qualified cables and an application-level check. That record is more useful than a family-name match.
Scope: Exact AN/AS distinction and legacy ACAT comparison. No measured latency or customer-outcome claims.