HPE 844480-B21 25Gb SFP28 Direct Attach Copper Cable
Overview
The HPE 844480-B21 is a 25 gigabit SFP28-to-SFP28 direct attach copper (DAC) cable rated for 5-meter runs. This is the cable you deploy when you need short-range, passive high-speed interconnect between switches, NICs, HBAs, or fabric modules without the complexity of active electronics or signal conditioning. Built to SFF-8665 standard and RoHS-compliant, it handles the bandwidth requirements of modern data center, server, and storage fabric architectures where latency and cost-per-connection matter.
Key Features
- 25 Gb/s data rate: Matches the speed of dual 10GbE or single 25GbE interfaces, so no bandwidth bottleneck between high-speed network appliances, compute nodes, or storage arrays. Unlike optical cables, no SFP28 transceiver cost per end.
- Direct Attach Copper (DAC) topology: Passive cable with no active components means zero power consumption, zero latency overhead, and zero firmware version dependencies. Plug and transmit — no transceiver compatibility matrix to chase. Ideal for fixed, short-distance deployments.
- 5-meter cable length: Covers most top-of-rack (ToR) to end-of-row distances and intra-rack fiber distribution panel runs without the expense of active breakout cables or long-range optics. Passive copper stays passive only to ~7m; beyond that, active or optical is mandatory.
- SFP28 to SFP28 connectors: Standard connector footprint ensures compatibility with industry-standard 25G SFP28 cage equipment — switches (Arista, Cumulus, Juniper, Cisco, etc.), NICs, HBAs, and fabric interconnects. No adapter required; no form-factor mismatch.
- SFF-8665 compliance: The small form factor interoperability standard governing SFP28 electrical and mechanical specs ensures plug-and-play compatibility across vendors and generations. No vendor lock-in, no custom ordering.
- RoHS certified: Lead-free, cadmium-free construction meets EU and US environmental regulations. Required for procurement into enterprise data centers, government facilities, and regulated industries (finance, healthcare, defense).
Integration & Compatibility
The 844480-B21 integrates with any equipment featuring standard SFP28 cages. Common deployment scenarios include:
- Data center switching fabric: Inter-switch links (ISLs) on 25G-capable switches for leaf-spine or CLOS architectures, reducing optics spend on short intra-row hops.
- Server-to-switch: Direct attach from dual-port 25GbE server NICs to TOR switches, bypassing intermediate aggregation layers in compact deployments.
- Storage array interconnect: Backend fabric between storage controllers, RAID accelerators, or NVMe-over-Fabrics (NVMe-oF) endpoints where sub-100μs latency and 25G throughput are prerequisites.
- HBA and fabric module uplinks: Fibre Channel over Ethernet (FCoE), iSCSI, or raw 25GbE uplinks from host adapter cards to core fabric switches.
The 5-meter passive specification precludes use in campus or multi-building links; for longer distances, upgrade to active breakout cables or single-mode optical SFP28 transceivers.
What's in the Box
The HPE 844480-B21 ships as a single 5-meter cable assembly with pre-terminated SFP28 connectors. No additional adapters, no connectors, no assembly required — unpack and patch.
Frequently Asked Questions
Q: Can I use the 844480-B21 in a 10-meter run?
A: No. Direct attach copper cables are passive and subject to signal attenuation over distance. HPE rates the 844480-B21 at 5 meters maximum. For longer runs, use an active breakout cable or switch to optical SFP28 transceivers.
Q: Does the 844480-B21 require any driver or firmware installation?
A: No. DAC cables are passive copper — there are no drivers, no firmware, and no software dependencies. Plug both SFP28 ends into matching cages, and the link autonegotiates at 25Gb/s.
Q: Is the 844480-B21 backwards compatible with 10Gb SFP+ equipment?
A: No. SFP28 connectors are mechanically and electrically distinct from SFP+ (10GbE). The 844480-B21 will not physically insert into an SFP+ cage. Do not force it.
Q: What is the latency of the 844480-B21?
A: Latency is negligible — typically <1 microsecond of propagation delay over 5 meters. Passive copper adds virtually no stack delay. For latency-sensitive applications (HFT, low-latency storage), DAC is preferred over optical.
Q: Does HPE offer a warranty on the 844480-B21?
A: HPE covers the 844480-B21 under its standard hardware warranty. Contact your HPE sales representative or reseller for warranty terms and conditions applicable to your purchase.
I spec the HPE 844480-B21 into fabric designs where every dollar per port and every microsecond of latency compounds across hundreds of links. The 5-meter passive DAC eliminates transceiver cost (typically $40–80 per SFP28 optical module) and guarantees sub-microsecond latency — neither of which you get with active breakout cables or optical, and both matter at scale. Model 844480-B21 (often searched as 844480 B21) handles the electrical and mechanical rigor of SFF-8665 compliance, so you're not chasing connector compatibility issues across vendor equipment.
Technical Highlights:
- 25 Gb/s full-duplex passive copper: Zero transceiver licensing overhead, zero power draw per cable, zero firmware version lock-in. Deploy a hundred of these in a leaf-spine fabric and your power and opex stay flat. Active cables or optics would add hundreds of watts and sustained module-refresh complexity.
- SFF-8665 standard compliance: Mechanical and electrical interop is guaranteed across Arista, Cumulus, Juniper, Cisco, Mellanox, and HPE equipment. No form-factor surprises, no cage fit issues — the cable works in any 25GbE SFP28 cage without exception.
- 5-meter length sweet spot: Covers 95% of intra-rack and rack-to-adjacent-row runs. Beyond 7 meters, passive copper hits attenuation limits and active conditioning becomes mandatory. This length is the economics inflection point: optical costs more, but passive copper fails you.
Deployment Considerations:
- Verify your switch and NIC firmware supports 25GbE SFP28 cages before order. Older ToR models (pre-2018) have SFP+ only — cable won't fit. Test in a non-production link first to confirm autonegotiation.
- DAC cables are distance-limited by physics. The 844480-B21 is rated to 5 meters passive; running it at 6–7 meters risks intermittent link flaps and frame loss under thermal stress. If your run exceeds 5 meters, do not try to stretch it — switch to active or optical immediately.
The 844480-B21 is the right choice for fixed leaf-spine spines, server-to-TOR uplinks in containerized data centers, and storage fabric backends where you're replacing optical every 3–5 years and want to cut that refresh cost in half. It is not for field-patching or temporary links where you might exceed 5 meters later.
