HPE QSFP28 to SFP28 Adapter — 845970-B21

The HPE 845970-B21 is the standard option kit for the HPE QSFP28 to SFP28 adapter, enabling a single 100GbE QSFP28 port to connect to a 25GbE SFP28 transceiver or device. This adapter allows network equipment with QSFP28 100GbE ports — switches, NICs, and storage controllers — to interface directly with 25GbE SFP28 endpoints, providing flexible 25GbE connectivity from 100GbE QSFP28 infrastructure without additional cabling or media converters.

Key Features

• QSFP28 to SFP28 adapter option kit — standard procurement for 25GbE SFP28 from QSFP28 ports
• Direct physical adapter — no active electronics, media converters, or external power required
• Standard option kit — regional/revision variant 849444-001 is interchangeable
• Flexible 25GbE SFP28 breakout from 100GbE QSFP28 switch and NIC ports

Product Specifications

• Part Number: 845970-B21
• Manufacturer: HPE
• Type: QSFP28 to SFP28 Adapter
• Input: QSFP28 (100GbE)
• Output: SFP28 (25GbE)

Transceiver & Interface Specifications

• Input Interface: QSFP28 — plugs into 100GbE QSFP28 port on switch, NIC, or HBA
• Output Interface: SFP28 — accepts 25GbE SFP28 transceiver for 25GbE connectivity
• Adapter Type: Passive mechanical adapter — no signal conversion or active electronics
• Speed: Enables single-lane 25GbE via one lane of the QSFP28 four-lane interface

Use Cases

• Standard option kit procurement for 25GbE SFP28 connectivity from QSFP28 HPE infrastructure
• Connecting 25GbE SFP28 servers or appliances to 100GbE QSFP28 switch ports
• Flexible 25GbE breakout from 100GbE QSFP28 without dedicated 25GbE switch ports
• Field adapter for mixed 25GbE/100GbE environments using HPE QSFP28-capable switches

Compatibility

• HPE switches and NICs with QSFP28 100GbE ports supporting SFP28 adapter mode
• HPE-validated 25GbE SFP28 transceivers for use in the SFP28 output port
• Interchangeable with 849444-001 in supported HPE QSFP28 configurations

Frequently Asked Questions

Is 845970-B21 interchangeable with 849444-001?

Yes — 845970-B21 is the standard option kit and 849444-001 is the regional/revision variant. Both are HPE QSFP28 to SFP28 adapters with identical function — fully interchangeable in supported HPE QSFP28 port configurations.

What is the maximum distance supported with this adapter?

Distance is determined by the SFP28 transceiver inserted into the adapter's SFP28 port — not by the adapter itself. Short-range 25GbE SFP28 SR transceivers support up to 100m over OM4 fiber; long-range LR transceivers support up to 10km. Select the SFP28 transceiver based on your required link distance.

Can I use multiple QSFP28 to SFP28 adapters on the same switch?

Yes — each QSFP28 port can independently use a QSFP28 to SFP28 adapter. However, each adapter uses one full QSFP28 port for a single 25GbE connection. For 4x 25GbE from a single QSFP28 port, a QSFP28 to 4x SFP28 breakout cable is more efficient than four separate adapters on four QSFP28 ports.

The HPE 845970-B21 QSFP28 to SFP28 adapter option kit enables flexible 25GbE SFP28 connectivity from 100GbE QSFP28 ports in HPE network infrastructure. Order today — in stock at a competitive price.