Q: Will this work in place of the Arista QSFP-100G-SR4?
A: Yes. The QSFP-100G-SR4-BCC is engineered to the same IEEE 802.3bm 100GBASE-SR4 and QSFP28 MSA specifications as the Arista QSFP-100G-SR4, with matching form factor, data rate, wavelength, and reach. It operates plug-and-play in Arista QSFP28 ports without configuration changes.

Q: Which Arista platforms support this transceiver?
A: This module works in any Arista switch or router with QSFP28 ports that support 100GBASE-SR4 optics. Compatibility is determined by the QSFP28 electrical interface and 100GBASE-SR4 standard support, not specific platform models. Verify your platform documentation lists 100GBASE-SR4 QSFP28 support.

Q: What is the difference in reach between OM3 and OM4 fibre, and why does it matter?
A: OM3 fibre supports up to 70m at 850nm due to higher modal dispersion, while OM4 offers 100m with lower attenuation and better modal bandwidth. The difference matters in data centre spine-leaf architectures where OM4 provides the margin needed for 100m end-of-row connections, while OM3 limits you to shorter top-of-rack runs.

Q: Can I use this transceiver in 4x25G breakout mode with a fanout cable?
A: Yes. The four independent 25Gbps lanes can be broken out via an MTP/MPO-12 to 4x duplex LC fanout cable. Each lane operates as a discrete 25GBASE-SR link. The host switch must support breakout configuration, and FEC requirements depend on your switch platform and NOS version.

Q: Does this module require FEC to achieve the rated 100m reach over OM4?
A: FEC is typically not required for the physical layer to reach 100m over OM4, as the 1.9dB link budget and 850nm VCSEL performance are sufficient. However, some switch platforms enable FEC by default for 100G interfaces to improve bit error rate margins. Check your platform behaviour, as FEC adds latency but improves link robustness in marginal installations.