INTERFACE DECISION / 01
Start with the full part number, not an MPO fiber count
“800G” describes the Ethernet rate, not one optical interface. Official Cisco and Arista 800G portfolios include MPO-16 APC, dual MPO-12 APC and duplex LC. Fiber type, port count and breakout capability can differ at the same nominal rate. [2] [4]
IEEE 802.3df-2024 completed relevant 800 Gb/s Ethernet work, but procurement still depends on the exact supported transceiver, MDI and cabling architecture. Do not infer the patching structure from “DR8”, “2×DR4” or “8×100G” alone. [1]
COMPARISON / 02
Common 800G optical interfaces: purchasing matrix
| Interface | Physical structure | Official examples | Purchasing check |
|---|---|---|---|
| MPO-16 APC | One interface with 16 parallel fiber positions | Official product examples for 800G DR8 / VR8 families | Confirm SMF or MMF, guide pins, key, lane map and the remote module |
| Dual MPO-12 APC | Two MPO-12 ports, each carrying a subset of lanes | Official product examples for 800G 2×DR4, 2×VSR4 and 8×100G | Define the two ports separately; do not reduce the requirement to a generic 24F interface |
| Duplex LC | One or two duplex LC ports using wavelength multiplexing | Official product examples for 800G 2×FR4 / 2×LR4 families | Confirm UPC, SMF, wavelength architecture, reach and the remote module |
Important: some 800G multimode MPO-12 products use APC end faces. Do not assume the common UPC assembly merely because the link is multimode. [4]
RFQ INPUTS / 03
Minimum configuration checklist for suppliers
| Category | Required input |
|---|---|
| Equipment | Switch model, port mode and system software requirements |
| Transceivers | Full part numbers at both ends, form factor and vendor compatibility matrix |
| Optical interface | MPO-16, dual MPO-12 or LC; APC/UPC; guide pins and key orientation |
| Link | Direct or breakout target, lane map, polarity, fiber type and connection count |
| Delivery | Length datum, labels, quantity, tests, report format and sample plan |
BUYER FAQ / 04
800G fiber cabling purchasing FAQ
Does every 800G transceiver use MPO-16?
No. Official vendor portfolios include MPO-16 APC, dual MPO-12 APC and duplex LC optical interfaces. Select cabling from the full transceiver part number and its data sheet.
Can dual MPO-12 be replaced by one MPO-16?
Not by adding fiber counts. The mechanical interface, port count, lane assignment and breakout architecture differ. Confirm both transceivers and the end-to-end map.
Can an existing 400G MPO-12 trunk always be reused for 800G?
No automatic reuse should be assumed. Some dual-MPO-12 architectures relate to 400G parallel interfaces, but end face, fiber type, polarity, loss budget, connections and vendor support still require review.
Are multimode MPO-12 interfaces always UPC?
No. Arista documents some 800G VSR4 modules with MPO-12 APC multimode interfaces and states they are incompatible with the MPO-12 UPC commonly used for 40G/100G SR4 links.
What is the minimum information for an RFQ?
Provide switch and transceiver part numbers, interface photos or data sheets, direct or breakout target, fiber type, length, connection count, quantity and test requirements.
SOURCES / 05
Sources and applicability
Sources checked: 2026-09-18. The matrix identifies procurement variables; it does not replace current transceiver data sheets, platform compatibility matrices, IEEE standards or approved project drawings.