HPE HP BLC QSFP+ to 4X10G SFP+ AOC 15M OPT - 721076-B21

HPE 721076-B21 QSFP+ to 4x10G SFP+ Active Optical Cable 15m

Overview

The HPE 721076-B21 is a 15-meter Active Optical Cable (AOC) that breaks a single QSFP+ port out into four independent 10GbE SFP+ connections — a direct answer to the bandwidth aggregation problem in high-density HPE BladeSystem and FlexFabric environments. If you're consolidating 10G uplinks from multiple blade enclosures into a spine switch without burning four discrete transceivers and four patch cables per hop, this is the interconnect to reach for. The 721076-B21 (often searched as 721076 B21) ships as a factory-terminated, active optical assembly: no field polishing, no separate transceivers to provision, no compatibility guesswork between ends.

Key Features

• QSFP+ to 4x10G SFP+ Fan-Out Architecture: One QSFP+ port on the switch side splits into four 10GbE SFP+ connections at the server or blade enclosure side. This means a single 40G QSFP+ switch port serves four 10G endpoints simultaneously — four times the port density from the same switch real estate.
• Active Optical Construction: Unlike passive copper DAC (Direct Attach Copper) cables, the active optical design embeds signal conditioning electronics at each end. This eliminates the signal degradation and EMI susceptibility that limits copper DAC runs, making optical the correct choice at 15m where copper's reliable reach typically ends well below this distance.
• 15-Meter Reach: 15m puts this cable squarely in the inter-rack and end-of-row aggregation range — long enough to span adjacent rows in a structured data center layout without resorting to fiber patch panels and separate transceivers. For in-rack runs, this is intentional overreach that gives you routing slack.
• 3mm Cable Diameter: At 3mm, the cable is slim enough for dense cable management trays without creating the airflow blockage associated with thicker twinax or multi-fiber trunk cables. In fully loaded blade chassis environments where horizontal cable management is already strained, the slimmer profile makes a tangible difference during installation.
• 25mm Minimum Bend Radius: A 25mm minimum bend radius is tighter than most structured fiber solutions, which matters in cramped rear-of-chassis routing. You can navigate 90-degree turns in standard cable management arms without risking fiber attenuation from overbending — provided you respect the 25mm floor.
• Integrated End-to-End Assembly: Factory-terminated AOCs eliminate the per-transceiver provisioning step. In HPE BladeSystem deployments where firmware-locked port authentication can reject third-party optics, using an HPE-branded AOC assembly avoids compatibility interrogation at switch initialization.

Integration and Compatibility

The 721076-B21 is designed for HPE BladeSystem c-Class enclosures and HPE FlexFabric switch infrastructure that expose QSFP+ uplink ports alongside 10GbE SFP+ server-side connections. The 4x10G fan-out topology is most directly applicable when connecting a blade enclosure's pass-through or switch module to a top-of-rack or end-of-row aggregation switch with 40G QSFP+ uplinks. Verify the QSFP+ port on your specific switch or Virtual Connect module supports fan-out mode — not all QSFP+ implementations enable 4x10G breakout in firmware. For structured cabling environments where HPE network switches are already deployed alongside fiber optic cabling infrastructure, the AOC format replaces the transceiver-plus-patch-cord approach with a single managed assembly, simplifying cable management and reducing the component count per link. Buyers evaluating HPE networking and interconnect options should confirm BladeSystem enclosure generation and Virtual Connect firmware revision for fan-out support before ordering. For guidance on planning 10G uplink capacity in blade environments, consult your network planning resources.

Frequently Asked Questions

Q: What is the cable length of the HPE 721076-B21?

A: The 721076-B21 is a 15-meter Active Optical Cable.

Q: Does the 721076-B21 use active or passive technology?

A: It is an Active Optical Cable (AOC), meaning it incorporates active signal conditioning electronics at each end — not a passive copper DAC assembly.

Q: What is the cable diameter and minimum bend radius of the 721076-B21?

A: The cable is 3mm in diameter with a minimum bend radius of 25mm.

Q: How many 10G connections does the 721076-B21 provide?

A: The cable provides four independent 10GbE SFP+ connections from a single QSFP+ port, enabling a 40G-to-4x10G fan-out topology.

Q: Is the 721076-B21 compatible with non-HPE switches?

A: The cable is designed for HPE BladeSystem and FlexFabric environments. Compatibility with non-HPE equipment depends on whether the third-party QSFP+ port supports 4x10G breakout mode and whether the port authenticates non-native optics — verify with your switch vendor before purchasing.

Jerry Tildsen

The 721076-B21 comes up consistently in HPE BladeSystem refresh projects where the team is consolidating 10G blade uplinks to a 40G-capable spine without doubling the transceiver count. The 15-meter reach is the spec that does the most work here — it covers inter-row aggregation distances that kill copper DAC options and removes the need for an intermediate fiber patch panel.

Technical Highlights:

• 15m AOC reach: Copper DAC at this distance is unreliable; optical gives you clean signal conditioning to 15m without the EMI sensitivity or the insertion-loss variability of field-terminated fiber.
• 3mm cable diameter: In a fully loaded c-Class enclosure bay with 16 blades and their associated uplinks, cable congestion in the rear is a real problem. 3mm versus a 5mm trunk makes a measurable difference in airflow and pull-through during installation.
• 25mm minimum bend radius: Tighter than typical LC duplex structured cabling minimums, which matters when you're routing through cable management arms on a blade chassis — you get the corner clearance without a separate bend-radius limiter accessory.

Deployment Considerations:

• Confirm your QSFP+ switch port or Virtual Connect module firmware explicitly supports 4x10G fan-out mode before installing — some QSFP+ ports operate only in 40G single-channel mode and will not negotiate the breakout topology.
• At 15m, the AOC assembly is fixed-length — plan your rack layout and cable path before ordering, since field-trimming an AOC is not an option.

This cable fits best in HPE BladeSystem c-Class environments doing a spine-leaf refresh where QSFP+ uplinks on the new leaf switches need to connect back to legacy 10GbE SFP+ server-side ports across an inter-row run — exactly the scenario where buying four individual transceivers plus four patch cords per link becomes operationally expensive fast.