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.

Optical Transceivers Cost You More Than You Think

In the world of high-performance networking, engineers and operators often focus their attention on the switch chassis itself. When evaluating power budgets or structural installation, it is common to view the switch as the primary, expensive "brain" of the system, while treating the SFP transceiver modules as mere auxiliary accessories—side components that add little to the overall system load. However, a closer analysis of high-density systems, such as the 48-port Cisco Catalyst 9500, proves that this assumption is a significant misconception.

This article examines the validity of this assumption. Let us look closer at all transceivers versus the switch main body.

Cisco Catalyst 9500 (C9500-48Y4C)
Source (Thanks!):
Cisco Catalyst 9500 Series Switches Hardware Installation Guide

25G transceiver (SFP-25G-SR-S)
Source (Thanks!):
Cisco 25GBASE SFP28 Modules Data Sheet

I choose Cisco Catalyst 9500 (C9500-48Y4C) as an example target for analysis. This Catalyst 9500 has forty-eight user ports, and I install forty-eight 25G transceivers (SFP-25G-SR-S) into each port. We analyze in three dimensions: Power Consumption, Heat Generation, and Financial Cost.

MPO/MTP Fiber Optic Connectors

To achieve higher transmission bit rate, Ethernet fiber optic transceivers often utilize parallel optics to transmit data across multiple fiber lanes simultaneously.

Think of a single pair of fibers as one data lane for sending and receiving. By bundling four pairs of fibers, a transceiver can transmit and receive four times the amount of data simultaneously. For instance, if a single fiber pair delivers a throughput of 10 Gbps, a four-pair configuration can scale up that speed fourfold to 40 Gbps.

Standard transceivers that only require a single pair of fibers typically use LC (Lucent Connector) interfaces. However, when a transceiver needs to connect multiple fiber pairs through a single port, it must use high-density MPO/MTP connectors.

MPO (Multi-fiber Push-On)

MPO is an open industry standard. Its name perfectly reflects its design philosophy: a high-density, multi-fiber connector with a simple push-on mating mechanism. Common configurations include MPO-8 (8 parallel fibers) and the more widespread MPO-12 (12 parallel fibers).

Figure 1: MPO-12 vs MPO-8
Source (Thanks!):
https://www.flukenetworks.com/blog/cabling-chronicles/getting-12-and-8-fiber-polarity-right

How do we fix a broken submarine fiber cable?

A submarine cable cutting incident happened recently at the Baltic Sea. Another similar incident also happened north of Taiwan. 

I wanted to know more about how to repair a broken submarine fiber cable. I did my research on the Internet. I summarize my findings and list the key fixing steps below.

1. The submarine cable was working.

Initially, the working submarine cable was below the sea water and above the seabed. The submarine cable follows and fits the terrain of seabed.

2. A fault happens.

Examples of faults are punctured insulation, fiber core breaks, and cable cut.

Faults could be natural factors, such as the aging of cable itself, earthquakes, falling rocks, and shark bites. Faults could also be human factors, such as fishing nets dragging, anchoring hits, and malicious sabotage.

How do we repair a broken submarine fiber cable?

(Updated here: https://showipprotocols.blogspot.com/2025/01/how-do-we-fix-broken-submarine-fiber.html)

On April 22, 2017, one segment of Asia-Pacific Cable Network 2 (APCN2) that serves Taiwan’s major Internet connectivity with Japan, Europe, and America, was broken. According to some news sources, it might take one month just to fix this outage. I live in Taiwan, and I do feel the Internet speed became slow after this outage. I was wondering how could the repairing take one month.

I want to know how to repair a broken submarine fiber cable. I searched on Google and I found this video. This video was created and published by TE SubCom. I summarize the key steps mentioned in this video, and I also added some of my own notes all in this post. I hope this post together with the original video would help you to understand the repairing operation as well.