DIGITUS 100G QSFP28 Direct Attach Cable (DAC), 1m, QSFP28 to QSFP28, 100GBASE-CR4, AWG 30 Twinax

The DIGITUS DN-81601 is a 1 m QSFP28 to QSFP28 direct attach copper cable for 100 Gigabit Ethernet (100GBASE-CR4, 4 × 25G lanes) between switches, servers and storage in the same rack.

A DAC replaces two optical transceivers and a fibre patch cord with a single factory-terminated assembly: lower cost, negligible power draw and no fibre end-faces to clean. The trade-off is reach and flexibility — the length is fixed, and copper twinax is meant for links inside one rack or to the rack next to it.

• 1 × DIGITUS DN-81601 QSFP28 DAC cable, 1 m, with QSFP28 connectors at both ends

• Four lanes of up to 28.3125 Gbps each carry a full 100G link over one cable — the usual choice for 100G spine-to-leaf or server uplinks inside a rack.
• 1 m covers switches in adjacent rack units or a server a few units below its top-of-rack switch.
• Hot-swappable: plug it in or pull it out while both devices are running; the port recognises the cable and brings the link up without separate optics.
• Measure the real cable route (through cable managers, around the rack posts) before choosing the length — a DAC cannot be shortened, and a long cable coiled inside the rack blocks airflow.

• It is not a breakout cable — splitting a 100G port into 4 × 25G needs a QSFP28-to-4×SFP28 cable.
• It will not fit SFP28 or SFP+ ports, and a 40G-only QSFP+ port will not run it at 100G.
• It cannot be extended or joined to another cable — if the distance grows, the answer is optics plus fibre, not a second DAC.
• It is not a breakout cable: it connects one port to one port of the same type.