QSFP-100G-CUxM-BCC | Cisco Compatible QSFP to QSFP Copper Direct-Attach 100GBASE-CR4 Cable | 1 to 5M

Q: Will this work in place of the Cisco QSFP-100G-CU1M?
A: Yes. This cable is a direct plug-and-play replacement for the Cisco QSFP-100G-CU1M series. It meets the IEEE 802.3bm 100GBASE-CR4 standard, uses the QSFP28 form factor, and delivers 100 Gbps over passive copper. It will function identically to the Cisco original in any compatible QSFP28 port.

Q: Which Cisco platforms support this cable?
A: This cable is compatible with Cisco switches and routers that feature QSFP28 100G ports and support 100GBASE-CR4 passive copper signaling per IEEE 802.3bm. Consult the Cisco 100 Gigabit Ethernet Transceiver Modules Compatibility Matrix for your specific platform model and software version to confirm QSFP-100G-CU1M support.

Q: What is the maximum reach for passive copper at 100 Gbps, and why does it vary by length?
A: Passive copper DAC cables use the electrical conductivity of the twinax copper pairs without signal regeneration. At 100 Gbps, cable attenuation and crosstalk limit reach to 5 meters maximum per the 100GBASE-CR4 specification. Longer cables within this range experience higher insertion loss, so choose the shortest length that fits your physical topology to maximize signal margin.

Q: Can I mix different cable lengths from this series on the same switch?
A: Yes. Each cable is an independent point-to-point link. The host switch treats each QSFP28 port separately, so you can install 1m, 2m, 3m, and 5m cables on adjacent ports without interaction. Electrical characteristics are matched to the cable length, and the QSFP28 EEPROM identifies each assembly independently to the host.

Q: Does this cable require Forward Error Correction (FEC) to be enabled on the host ports?
A: The 100GBASE-CR4 standard does not mandate FEC for passive copper cables at these lengths. Host switches typically auto-negotiate FEC settings during link bring-up. If your network operating system allows manual FEC configuration, the cable will operate correctly with FEC enabled or disabled, though enabling FEC may provide additional margin on longer cable runs or in electrically noisy rack environments.