Aruba J4859D — 1000BASE-LX SFP (1310 nm, 10 km, SMF, LC)

What it is: A 1 GbE SFP transceiver that runs 1000BASE-LX/LH at 1310 nm over single-mode fiber (SMF). Standard duplex LC connector, MSA-compliant, and supports DOM/DDM (digital diagnostics). The classic “go-to” 1G long-reach optic for campus backbones and access uplinks.

Why buyers pick J4859D (plain English)

• Proven 1G long reach: up to 10 km on SMF without special optics.

• Drop-in SFP footprint: fits Aruba/HPE switches with SFP slots; LC patching you already have.

• Troubleshoot fast: DOM/DDM lets you see Tx/Rx power, temp, and voltage from the CLI/GUI.

60-second spec box

Optics & reach

• Wavelength: 1310 nm (LX)

• Fiber / connector: SMF (G.652), duplex LC

• Max distance: up to 10 km on SMF

• MMF support: works on legacy MMF runs (e.g., OM1/OM2) for short distances when used with a mode-conditioning patch (MCP)

Line rate & standards

• 1.25 Gbps (Gigabit Ethernet line rate)

• IEEE 802.3z 1000BASE-LX/LH, SFP MSA compliant

• DOM/DDM supported

Optical performance (typical class)

• Tx type: 1310 nm laser (often FP/DFB)

• Power budget: sufficient for standard 10 km SMF links with typical connector/splice loss (verify your exact plant)

Electrical / power

• Supply: 3.3 V

• Module power: ~1 W (typical for LX SFPs)

Environment

• Operating temp: 0 to +70 °C (commercial)

• Hot-pluggable SFP form factor

Where it fits (and when to choose something else)

• Perfect for: 1G access-to-distribution uplinks, building-to-building runs across campus, and any SMF span up to 10 km.

• Use SX (850 nm) for short in-building MMF links (≤550 m on OM2/OM3/OM4).

• Use ZX/ER-class if you need >10 km on SMF.

• Use copper SFPs or DAC for very short cabinet/rack links at the lowest cost/power.

Quick design tips (no-regret)

• Budget the link: sum fiber attenuation + connector/splice losses; keep within the module’s budget with a 1–2 dB safety margin.

• Short MMF runs? If you must run LX over MMF, use the correct MCP at the transmit end(s) to avoid differential mode delay.

• Clean your LCs: most “mystery” errors are dirty ferrules—clean before testing.

• Label both ends (port, wavelength, distance) to avoid mixing with SX modules.

TL;DR

J4859D = 1G SFP, 1310 nm, up to 10 km on SMF, LC duplex, with DOM. It’s the reliable, drop-in 1000BASE-LX optic for campus and access uplinks when SX doesn’t reach and you don’t need the cost/complexity of longer-haul optics.