USFP: A Quantum Leap in Ethernet Transceiver Specifications Announced

On October 12, 2026, Nvidia and Cisco jointly announced the new 6.4Tbps USFP (Ultra-Dense Small Form Factor Pluggable) Ethernet transceiver specification.

Source: Nvidia

• Phase 1 USFP: Designed with sixteen lanes at 400Gbps per lane, aggregating to a total bandwidth of 6.4Tbps (6,400 Gbps).
• Phase 2 USFP: Planned to expand to thirty-two lanes, doubling the aggregate bandwidth to 12.8Tbps (12,800 Gbps).

Because USFP is currently only a newly released specification without physical commercial products on the market, the following analysis is based on theoretical specification projections.

Seven months prior, on March 12, 2026, Arista unveiled its XPO (eXtra-dense Pluggable Optics) specification. XPO utilizes sixty-four lanes at 200Gbps per lane to achieve a total aggregated bandwidth of 12.8Tbps.

Since both USFP and XPO were created to address the massive bandwidth demands of AI workloads, here is a handy head-to-head comparison of their specifications.

Key Advantages of USFP Over Arista XPO

1. Smaller Panel Footprint and Compact Form Factor

While exact dimensions have not been fully disclosed, USFP is reported to be similar in size to the existing OSFP standard. Below, the focus is placed on width and height, as these two dimensions dictate panel density on switches and Network Interface Cards (NICs).

See accompanying diagram for scaled width and height comparisons of common transceivers.

2. Lower Thermal Dissipation & Air-Cooling Compatibility

The USFP specification mandates a thermal power dissipation cap under 100W. Keeping power low allows systems to rely on traditional air cooling, keeping module sizes small without requiring extra physical space for liquid-cooling piping. In contrast, a single Arista XPO transceiver typically exceeds 400W, making liquid cooling mandatory and significantly increasing the overall module footprint and transceiver volume.

3. Defined for both Servers and Switches use

A standout feature of USFP is its unified specification for both switch and server environments, allowing switches and servers to share identical transceiver modules. Conversely, Arista designed XPO primarily for switch-to-switch interconnects without defining server-side application. Furthermore, server chassis are generally unable to support the massive ~400W power draw of a single XPO module.

4. Up to 2x Potential Switch Bandwidth per Rack Unit (RU)

Thanks to its smaller panel footprint, more USFP modules can be packed into a 1RU switch faceplate. Current size estimates suggest a 1RU panel can fit only 16 XPO modules, whereas it can fit 32 USFP modules.

In Phase 1 USFP, transceivers only achieve 6.4 Tbps, whereas XPO achieves 12.8Tbps. Thirty-two USFP ports offer the same bandwidth as sixteen XPO. Phase 1 USFP only offers higher port density (32 vs 16) rather than higher total bandwidth.

Once USFP reaches its Phase 2 specification (12.8Tbps per module), total throughput per 1RU switch could reach twice that of an XPO-based 1RU switch.

Where Arista XPO Maintains an Advantage

1. Time-to-Market Advantage: XPO was announced seven months earlier (March 2026).
2. Technological Maturity: XPO relies on 200Gbps/lane SerDes technology, which is technologically closer to volume production than USFP’s 400Gbps/lane. Although currently shown only as demonstration samples, XPO is expected to reach commercial availability faster.
3. Single-Module Link Speed: A single XPO module delivers 12.8Tbps out-of-the-box today (64 lanes x 200Gbps). For point-to-point switch links requiring 12.8T bandwidth immediately, XPO offers a quicker solution.

Conclusion

While both standards aim to solve the bandwidth bottlenecks of AI computing, they target distinct deployment scenarios. XPO focuses primarily on high-capacity switch-to-switch backbones, whereas USFP bridges both switch and server endpoints. Rather than directly competing to replace each other, examining these two specifications highlights the physical and thermal tradeoffs shaping the future of ultra-high-speed Ethernet optics.