Arista QDD-400G-XDR4-S-Arista | 400G QSFP-DD Transceiver, Single-Mode, 2km, MPO-12

Q: What is the difference between 400G XDR4 and DR4 transceivers?
A: 400G XDR4 (extended distance reach) supports up to 2km over single-mode fiber, while DR4 supports up to 500m. Both use 4 optical channels at 100Gbps each with 1310nm wavelength and MPO-12 connectors, but XDR4 offers greater reach for campus or inter-building deployments.

Q: Can this transceiver be used for 100G breakout connections?
A: Yes, the QDD-400G-XDR4-S supports breakout functionality when the host switch supports it. Using an MPO-to-LC breakout cable, it can connect to four 100G QSFP28 modules, making it ideal for connecting 400G switches to 100G infrastructure.

Q: Is this QSFP-DD module backward compatible with QSFP28 or QSFP56 ports?
A: No, QSFP-DD modules cannot be used in QSFP28 or QSFP56 ports due to the different form factors. However, QSFP-DD ports can accept QSFP28 and QSFP56 modules for backward compatibility.

Q: What type of fiber cable is required for this transceiver?
A: This transceiver requires single-mode fiber (SMF) cable with MPO-12 or MTP-12 connectors. The parallel optics design uses 4 transmit and 4 receive fibers (8 total) within the MPO-12 connector for 400Gbps aggregate bandwidth.

Q: Does this module support Forward Error Correction (FEC)?
A: Yes, FEC is supported and typically performed on the host platform. The module integrates an 8-channel retimer and FEC block in the DSP, ensuring reliable transmission over the 2km distance with PAM4 modulation.