Congestion Avoidance in AI Fabric – Part II: Priority Flow Control (PFC)

Priority Flow Control (PFC) is a mechanism designed to prevent packet loss during network congestion by pausing traffic selectively based on priority levels. While the original IEEE 802.1Qbb standard operates at Layer 2, using the Priority Code Point (PCP) field in Ethernet headers, AI Fabrics rely on Layer 3 forwarding, where traditional Layer 2-based PFC is no longer applicable. To extend lossless behavior across routed (Layer 3) networks, DSCP-based PFC is used.

In DSCP-based PFC, the Differentiated Services Code Point (DSCP) field in the IP header identifies the traffic class or priority. Switches map specific DSCP values to internal traffic classes and queues. If congestion occurs on an ingress interface and a particular priority queue fills beyond a threshold, the switch can send a PFC pause frame back to the sender switch, instructing it to temporarily stop sending traffic of that class—just as in Layer 2 PFC, but now triggered based on Layer 3 classifications.

This behavior differs from Explicit Congestion Notification (ECN), which operates at Layer 3 as well but signals congestion by marking packets instead of stopping traffic. ECN acts on the egress port, informing the receiver to notify the sender to reduce the transmission rate over Continue reading

Why I joined Cloudflare as Chief People Officer — Kelly Russell

After years navigating the exhilarating world of high-growth tech, from Amazon to Twilio’s scaling journey and most recently Wiz’s rapid ascent, I’ve learned to recognize a truly special opportunity when I see one. That’s exactly what I have found at Cloudflare and why I’m thrilled to join. 

What drew me to Cloudflare was the unique combination of a powerful mission, a transparent and results-oriented culture, and the sheer scale of impact. Cloudflare isn’t just a technology company —  it’s a force for good, building a better Internet for everyone. This really resonates with my own values.  

Success starts with people

My career has been defined by building, scaling, and developing teams in dynamic environments.  I’ve witnessed the transformative power of a strong culture in driving hypergrowth. I’ve experienced the intensity and agility required to disrupt a market. These experiences have reinforced my belief that people are the heart of any successful company, and that a people-first strategy is critical for long-term impact. During my interview process at Cloudflare, this belief was clearly evident in every conversation. Cloudflare is a place where people can do their best work and be proud of the impact they are making. Powered Continue reading

Tech Bytes: Get Data Center Automation as-a-Service with Nokia Event-Driven Automation (Sponsored)

Nokia Event-Driven Automation (EDA) is a modern infrastructure automation platform that combines speed with reliability and simplicity. It makes data center network automation more trustable and easier to use, from small edge clouds to the largest AI fabrics. Today on Tech Bytes, we talk with Sam Arora from Nokia for more details about some of... Read more »

Developer Week 2025 wrap-up

As we conclude Developer Week 2025, we’re proud to reflect upon the capabilities we’ve added to our developer platform. It’s so rewarding to deliver products, features and tools that help developers build smarter and ship faster, and even more so hearing your responses throughout the week!

Our VP of Product, Rita Kozlov, kicked off Developer Week 2025 discussing the ever-evolving landscape of development, particularly in the age of AI. AI is no longer just a buzzword or a trope for a science-fiction future — in the realm of modern development, it’s a core tenet (and utility) of how we build, innovate, and solve problems. It’s influencing how and how frequently we ship code, as well as enabling anyone to write it.

It’s exciting to not only witness this technical revolution, but also to be building a platform that enables developers to be part of it. We want to hear your feedback and see what you build with the new capabilities — reach out to us on Discord or X.

Here’s a recap of our Developer Week 2025 announcements:

Monday, April 7

Announcement

Summary

Piecing together the Agent puzzle: MCP, authentication & authorization, and Durable Objects free tier 

Toolkit for AI Continue reading

DNS at IETF122

One of the more active areas of activity at the IETF falls under the remit of the DNS Operations Working Group. These days the Internet is to all intents and purposes a name-based network. Our framework for supporting rendezvous, authenticity, and encryption is based on this name infrastructure. Little wonder that the DNS has engendered so much attention in the IETF.

🚀 One Month with Vibe Coding: Building Real Apps with AI Assistants

Over the past few months, Vibe coding has been gaining serious traction—and I couldn’t resist diving in myself. I’ve been using AI coding assistants for a while, but I wanted to go deeper and really test what these tools can do in a realistic, end-to-end software development project. So, I spent the last month building … Continue reading 🚀 One Month with Vibe Coding: Building Real Apps with AI Assistants →

Congestion Avoidance in AI Fabric – Part I: Explicit Congestion Notification (ECN)

As explained in the preceding chapter, “Egress Interface Congestions,” both the Rail switch links to GPU servers and the inter-switch links can become congested during gradient synchronization. It is essential to implement congestion control mechanisms specifically designed for RDMA workloads in AI fabric back-end networks because congestion slows down the learning process and even a single packet loss may restart the whole training process.

This section begins by introducing Explicit Congestion Notification (ECN) and Priority-based Flow Control (PFC), two foundational technologies used in modern lossless Ethernet networks. ECN allows switches to mark packets, rather than dropping them, when congestion is detected, enabling endpoints to react proactively. PFC, on the other hand, offers per-priority flow control, which can pause selected traffic classes while allowing others to continue flowing.

Finally, we describe how Datacenter Quantized Congestion Notification (DCQCN) combines ECN and PFC to deliver a scalable and lossless transport mechanism for RoCEv2 traffic in AI clusters.

GPU-to-GPU RDMA Write Without Congestion


The figure 11-1 illustrates a standard Remote Direct Memory Access (RDMA) Write operation between two GPUs. This example demonstrates how GPU-0 on Host-1 transfers local gradients (∇₁ and ∇₂) from memory to GPU-0 on Host-2. Both GPUs use RDMA-capable NICs connected Continue reading

HN776: Security Platforms: Balancing Efficacy, Ops, and Emerging Threats (Sponsored)

Network security has evolved from stateful perimeter firewalls with maybe some IDS/IPS to a complex stack delivered as numerous unique tools, which often don’t talk to one another and may need to be operated by specialists. In this environment it’s hard to unify a security policy, troubleshoot problems, manage and operate tools, and respond effectively... Read more »

TNO024: Networks for AI and AI for Networks — A Dual Perspective with Aviz Networks (Sponsored)

On today’s show, we introduce Aviz Networks with Vishal Shukla, Co-Founder & CEO. Vishal and Aviz are making Networks for AI, and AI for Networks. Vishal explains how Aviz does this by offering AI Networking Unpacked. Designed for open-source and vendor-agnostic networking, AI Networking Unpacked works with existing network infrastructures. It also integrates with existing... Read more »

Weekend Reads 041125


Amazon was a major player in ICANN’s last top-level domain (TLD) expansion round, serving as a Registry Operator for over 50 TLDs based on over 70 strings for which they originally applied.


A recent influx of /16 IPv4 address blocks has sent ripples through the secondary market, triggering a notable decline in average sale prices for the largest address sizes.


It is best to appreciate the challenge. AI data centers are projected to consume approximately two to three percent of U.S. electrical consumption this year alone, with expectations of continued growth now a given.


Interestingly, a fiber cut to an undersea fiber doesn’t cause as much harm as most people imagine. This map that shows all of the current submarine cable routes. There are a huge amount of redundant routes to most of the world.


Is it actually possible to run a team without lying? Steven Gaffney, author of the book, “Just Be Honest”, joins Johna and John to talk about why being honest is harder than it sounds–and how (and why) to do it anyway.

Simple, scalable, and global: Containers are coming to Cloudflare Workers in June 2025

It is almost the end of Developer Week and we haven’t talked about containers: until now. As some of you may know, we’ve been working on a container platform behind the scenes for some time.

In late June, we plan to release Containers in open beta, and today we’ll give you a sneak peek at what makes it unique.

Workers are the simplest way to ship software around the world with little overhead. But sometimes you need to do more. You might want to:

  • Run user-generated code in any language

  • Execute a CLI tool that needs a full Linux environment

  • Use several gigabytes of memory or multiple CPU cores

  • Port an existing application from AWS, GCP, or Azure without a major rewrite

Cloudflare Containers let you do all of that while being simple, scalable, and global.

Through a deep integration with Workers and an architecture built on Durable Objects, Workers can be your:

  • API Gateway: Letting you control routing, authentication, caching, and rate-limiting before requests reach a container

  • Service Mesh: Creating private connections between containers with a programmable routing layer

  • Orchestrator: Allowing you to write custom scheduling, scaling, and health checking logic for your containers

Instead Continue reading

Startup spotlight: building AI agents and accelerating innovation with Cohort #5

With quick access to flexible infrastructure and innovative AI tools, startups are able to deploy production-ready applications with speed and efficiency. Cloudflare plays a pivotal role for countless applications, empowering founders and engineering teams to build, scale, and accelerate their innovations with ease — and without the burden of technical overhead. And when applicable, initiatives like our Startup Program and Workers Launchpad offer the tooling and resources that further fuel these ambitious projects.

Cloudflare recently announced AI agents, allowing developers to leverage Cloudflare to deploy agents to complete autonomous tasks. We’re already seeing some great examples of startups leveraging Cloudflare as their platform of choice to invest in building their agent infrastructure. Read on to see how a few up-and-coming startups are building their AI agent platforms, powered by Cloudflare.

Lamatic AI built a scalable AI agent platform using Workers for Platform

Founded in 2023, Lamatic.ai empowers SaaS startups to seamlessly integrate intelligent AI agents into their products. Lamatic.ai simplifies the deployment of AI agents by offering a fully managed lifecycle with scalability and security in mind. SaaS providers have been leveraging Lamatic to replatform their AI workflows via a no-code visual builder to reduce technical debt Continue reading

A global virtual private cloud for building secure cross-cloud apps on Cloudflare Workers

Today, we’re sharing a preview of a new feature that makes it easier to build cross-cloud apps: Workers VPC. 

Workers VPC is our take on the traditional virtual private cloud (VPC), modernized for a network and compute that isn’t tied to a single cloud region. And we’re complementing it with Workers VPC Private Links to make building across clouds easier. Together, they introduce two new capabilities to Workers:

  1. A way to group your apps’ resources on Cloudflare into isolated environments, where only resources within a Workers VPC can access one another, allowing you to secure and segment app-to-app traffic (a “Workers VPC”).

  2. A way to connect a Workers VPC to a legacy VPC in a public or private cloud, enabling your Cloudflare resources to access your resources in private networks and vice versa, as if they were in a single VPC (the “Workers VPC Private Link”).

Workers VPC and Workers VPC Private Link enable bidirectional connectivity between Cloudflare and external clouds

When linked to an external VPC, Workers VPC makes the underlying resources directly addressable, so that application developers can think at the application layer, without dropping down to the network layer. Think of this like a Continue reading

Startup Program update: empowering every stage of the startup journey

During Cloudflare’s Birthday Week in September 2024, we introduced a revamped Startup Program designed to make it easier for startups to adopt Cloudflare through a new credits system. This update focused on better aligning the program with how startups and developers actually consume Cloudflare, by providing them with clearer insight into their projected usage, especially as they approach graduation from the program.

Today, we’re excited to announce an expansion to that program: new credit tiers that better match startups at every stage of their journey. But before we dive into what’s new, let’s take a quick look at what the Startup Program is and why it exists.

A refresher: what is the Startup Program?

Cloudflare for Startups provides credits to help early-stage companies build the next big idea on our platform. Startups accepted into the program receive credits valid for one year or until they’re fully used, whichever comes first.

Beyond credits, the program includes access to up to three domains with enterprise-level services, giving startups the same advanced tools we provide to large companies to protect and accelerate their most critical applications.

We know that building a startup is expensive, and Cloudflare is uniquely positioned to support the full-stack Continue reading

How we simplified NCMEC reporting with Cloudflare Workflows

Cloudflare plays a significant role in supporting the Internet’s infrastructure. As a reverse proxy by approximately 20% of all websites, we sit directly in the request path between users and the origin, helping to improve performance, security, and reliability at scale. Beyond that, our global network powers services like delivery, Workers, and R2 — making Cloudflare not just a passive intermediary, but an active platform for delivering and hosting content across the Internet.

Since Cloudflare’s launch in 2010, we have collaborated with the National Center for Missing and Exploited Children (NCMEC), a US-based clearinghouse for reporting child sexual abuse material (CSAM), and are committed to doing what we can to support identification and removal of CSAM content.

Members of the public, customers, and trusted organizations can submit reports of abuse observed on Cloudflare’s network. A minority of these reports relate to CSAM, which are triaged with the highest priority by Cloudflare’s Trust & Safety team. We will also forward details of the report, along with relevant files (where applicable) and supplemental information to NCMEC.

The process to generate and submit reports to NCMEC involves multiple steps, dependencies, and error handling, which quickly became complex under Continue reading

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