Find Out About 100G and 40G DAC Breakouts
High-Speed Short-Reach Connectivity
A Practical Guide to 100G and 40G DAC Breakout Cables
Breakout cables let one high-bandwidth switch port serve four lower-speed ports on compatible servers, storage systems or downstream switches. For short rack-level connections, a passive DAC design combines the cable and connectors into one assembly, reducing the number of separate components required for each link.
Shop DAC Breakout Cables
Choose the port configuration first, then select the 3 ft. or 7 ft. length that fits your rack layout.
QSFP28 to 4 × SFP28
Split one 100G QSFP28 port into four individual 25G SFP28 connections.
QSFP+ to 4 × SFP+
Split one 40G QSFP+ port into four individual 10G SFP+ connections.
Four Independent Links
Convert one high-speed port into four lower-speed connections.
Passive Copper
No separate optical transceivers are required.
Low Power Use
Consumes less than 0.1 W per cable end.
Broad Compatibility
MSA- and IBTA-compliant for compatible equipment.
How Breakout Connections Work
Use One High-Bandwidth Port More Efficiently
A breakout connection divides the lanes of a QSFP-family port into four separate links. With a 100G QSFP28 cable, four 25G lanes terminate at four SFP28 connectors. With a 40G QSFP+ cable, four 10G lanes terminate at four SFP+ connectors. Each device receives its own link while the switch uses one high-density QSFP-family port.
This can help connect multiple servers or storage systems to a top-of-rack switch without dedicating a separate high-speed switch port to every endpoint. It can also support short switch-to-switch links when both devices and their port configurations support the required breakout mode.
A complete cable assembly replaces a pair of separate optical transceivers and a fiber cable.
Each end consumes less than 0.1 W, helping limit power use across dense deployments.
Twinax construction supports direct, low-latency connections for high-performance networking.
The 3 ft. and 7 ft. options cover common same-rack and nearby-equipment layouts.
Where DAC fits best: Use passive DAC for short, direct connections. Longer distances, pathways between rooms or links that require electrical isolation may call for optical transceivers and fiber instead.
Choose the Right Configuration
100G-to-25G or 40G-to-10G?
The correct cable is determined by the port types and speeds on both sides of the link. QSFP28 and QSFP+ share a similar physical form, but they serve different Ethernet generations and should not be selected by connector shape alone.
Choose 100G QSFP28 to 4 × 25G SFP28
Use this configuration when the switch provides a compatible 100G QSFP28 port and the four connected devices use 25G SFP28 ports.
Standards: IEEE 802.3ba, IEEE 802.3by, SFF-8402 and SFF-8665
Choose 40G QSFP+ to 4 × 10G SFP+
Use this configuration when the switch provides a compatible 40G QSFP+ port and the four connected devices use 10G SFP+ ports.
Standards: IEEE 802.3ba, IEEE 802.3ae, SFF-8436 and SFF-8431
Compatibility comes first: Before ordering, confirm that the host switch supports breakout mode on the selected QSFP28 or QSFP+ port and that the four destination ports match the cable's SFP28 or SFP+ configuration. MSA compliance supports broad interoperability, but the connected hardware still needs the correct port type, speed and breakout settings.
3 ft. for Close Equipment
A strong fit for devices mounted near one another in the same rack, especially when a shorter route reduces cable slack.
7 ft. for More Routing Flexibility
Useful when the connection needs to pass through rack cable managers, span more vertical distance or reach nearby equipment.
Routing tip: Maintain at least the specified 2.36 in. minimum bend radius. Tight bends can place unnecessary stress on the cable and connectors.
Deployment Checklist
Confirm These Details Before Installation
Find the Right Breakout Cable for Your Rack
Compare 100G-to-25G and 40G-to-10G configurations in 3 ft. and 7 ft. lengths for compatible short-reach network connections.
