Lab: Running IS-IS over IPv4 Unnumbered and IPv6 LLA Interfaces

IS-IS does not use IPv4 or IPv6, so it should be a no-brainer to run it over IPv4 unnumbered or IPv6 LLA interfaces. The latter is true; the former is smack in the middle of the It Depends™ territory.

Want to know more or test the devices you’re usually working with? The Running IS-IS Over Unnumbered/LLA-only Interfaces lab exercise is just what you need.

Click here to start the lab in your browser using GitHub Codespaces (or set up your own lab infrastructure). After starting the lab environment, change the directory to basic/7-unnumbered and execute netlab up.

AUSNOG 2025

The Australian Network Operators' Group, AUSNOG, held its 19th meeting at the start of September. Rather than simply relate the content of the presentations I'd like to take a few presentations and place them into a broader context to show how such topics fit today's networked environment.

Securing AI Workloads in Kubernetes: Why Traditional Network Security Isn’t Enough

The AI revolution is here, and it’s running on Kubernetes. From fraud detection systems to generative AI platforms, AI-powered applications are no longer experimental projects; they’re mission-critical infrastructure. But with great power comes great responsibility, and for Kubernetes platform teams, that means rethinking security.

But this rapid adoption comes with a challenge: 13% of organizations have already reported breaches of AI models or applications, while another 8% don’t even know if they’ve been compromised. Even more concerning, 97% of breached organizations reported that they lacked proper AI access controls. To address this, we must recognize that AI architectures introduce entirely new attack vectors that traditional security models aren’t equipped to handle.

AI Architectures Introduce New Attack Vectors

AI workloads running in Kubernetes environments introduce a new set of security challenges. Traditional security models often fall short in addressing the unique complexities of AI pipelines, specifically related to The Multi-Cluster Problem, The East-West Traffic Dilemma, and Egress Control Complexity. Let’s explore each of these critical attack vectors in detail.

The Multi-Cluster Problem

Most enterprise AI deployments don’t run in a single cluster. Instead, they typically follow this pattern:

Training Infrastructure (GPU-Heavy)

The Curious Case of ‘ip host’ Configuration Command

Since time immemorial, I have used the ip host router configuration command to get host-to-IP mappings in networking labs without going through the hassle of setting up a DNS server. Some devices even accepted multiple IP addresses in the ip host command, allowing you to list all router interfaces in a single command and get reverse (IP-to-host) mapping working like a charm. Or so I thought 🤦‍♂️

It turns out I’m too old, and what I know is sometimes no longer true. It seems that the last implementation working as I expected is Cisco IOS Classic ☹️

Read more …

Packet trimming

The latest version of the AI Metrics dashboard uses industry standard sFlow telemetry from network switches to monitor the number of trimmed packets to use as a congestion metric.

Ultra Ethernet Specification Update describes how the Ultra Ethernet Transport (UET) Protocol has the ability to leverage optional “packet trimming” in network switches, which allows packets to be truncated rather than dropped in the fabric during congestion events. As packet spraying causes reordering, it becomes more complicated to detect loss. Packet trimming gives the receiver and the sender an early explicit indication of congestion, allowing immediate loss recovery in spite of reordering, and is a critical feature in the low-RTT environments where UET is designed to operate.

cumulus@switch:~$ nv set system forwarding packet-trim profile packet-trim-default
cumulus@switch:~$ nv config apply

NVIDIA Cumulus Linux release 5.14 for NVIDA Spectrum Ethernet Switches includes support for Packet Trimming. The above command enables packet trimming, sets the DSCP remark value to 11, sets the truncation size to 256 bytes, sets the switch priority to 4, and sets the eligibility to all ports on the switch with traffic class 1, 2, and 3. NVIDA BlueField host adapters respond to trimmed packets to ensure fast congestion recovery.

Continue reading

Labbing Network Technology Details with netlab

It’s been over four years since I published the last Software Gone Wild episode. In the meantime, I spent most of my time developing an open-source labbing tool, so it should be no surprise that the first post-hiatus episode focused on a netlab use case: how Ethan Banks (of the PacketPushers fame) is using the tool to quickly check the technology details for his N is for Networking podcast.

As expected, our discussion took us all over the place, including (according to Riverside AI):

Read more …

Why IT-Site1 Can’t Ping OT_Site1R – Show and Tell Time #1

In my earlier blog post, Troubleshooting OT Security: Why IT-Site1 Can’t Ping OT_Site1R, we discovered the reason for this issue. Our “who done it” is simple. For security reasons, we are using Cisco TrustSec to keep them from communicating. Which... Read More ›

The post Why IT-Site1 Can’t Ping OT_Site1R – Show and Tell Time #1 appeared first on Networking with FISH.

Navigating DORA with Calico: Strengthening Kubernetes Operational Resilience in Financial Services

A single cyberattack or system outage can threaten not just one financial institution, but the stability of a vast portion of the entire financial sector. For today’s financial enterprises, securing dynamic infrastructure like Kubernetes is a core operational and regulatory challenge. The solution lies in achieving DORA compliance for Kubernetes, which transforms your cloud-native infrastructure into a resilient, compliant, and secure backbone for critical financial services.

The Challenge DORA Seeks to Solve

Before DORA (Digital Operational Resilience Act), rules for financial companies primarily focused on making sure they had enough financial capital to cover losses. But what if a cyberattack or tech failure brought a large part of the financial system down? Even with plenty of financial capital, a major outage could stop most operations and cause big problems for the whole financial market. DORA steps in to fix this. It’s all about making sure financial firms can withstand, respond to, and recover quickly from cyberattacks and other digital disruptions.

What is DORA?

The Digital Operational Resilience Act (DORA) is a European Union (EU) regulation that came into effect on January 17, 2025 and is designed to strengthen the security of financial entities. It establishes uniform requirements across the financial Continue reading

HW060: CNAE – A New Wired Networking Certification From the CWNP

The CWNP offers vendor-neutral certifications for wireless networking professionals. This summer, the organization rolled out a wired certification, the Certified Network Administrator and Engineer (CNAE). This cert is aimed at wired and wireless network engineers to ensure they have a solid grounding in switching, routing, cabling, and wired protocols. The CWNP says the cert isn’t... Read more »

Worth Reading 090925


The arrangements regarding the composition and organisation of the provision and operation of authoritative root servers are one of the more long-lasting aspects of the public Internet.


Microsoft has achieved a breakthrough in the hollow core fiber technology, reducing data transmission loss to just 0.091 dB per kilometer, the lowest ever achieved and significantly below the 0.14 dB/km limit that has constrained fiber networks for decades.


China has pursued a strategy of competition among government-owned organizations, and it initiated two government-owned constellation projects, Hongyun and Hongyan, in 2018.


There is no question that one of the smartest things that chip designer, packager, and manufacturing process manager Marvell Technology did was to shell out $650 million in May 2019 to buy Avera Semiconductor.


In early 2024, a Hong Kong-based clerk at multinational consulting engineering firm Arup was duped into transferring about $25 million to scammers who used AI to impersonate the company’s CFO, and other senior executives, in a live video meeting.

PP077: News Roundup–Drift Breach Has Long Reach; FCC Investigates Its Own IoT Security Program

Is any publicity good publicity? On today’s News Roundup we talk about how Salesloft, which makes the Drift chat agent that’s been used as a jumping-off point for credential harvesting and data breach attacks against a bunch of big-name companies, is testing that proposition. We also discuss bugs affecting industrial refrigeration controllers, and Microsoft making... Read more »

Creating a Talos Linux Cluster on AWS with Pulumi, 2025 Edition

A little over two years ago, I wrote a post on creating a Talos Linux cluster on AWS using Pulumi. At the time of that post, the Pulumi provider for Talos was still a prerelease version. Since then, the Talos provider has undergone some notable changes necessitating an update to the example code I have on GitHub. For your reading pleasure, therefore, I present you with the 2025 edition of a tutorial for using Pulumi to create a Talos Linux cluster on AWS.

The updated Pulumi code can be found in this GitHub repository. Note that I’ve tagged the original version from the 2023 blog post with the “2023-post” tag, in the event you’d like to see the original code. While I chose to write my Pulumi code in Go, note that Pulumi supports a number of different languages (such as JavaScript/TypeScript, Python, one of the .NET languages, Java, or even YAML). I leave it as an exercise for the reader to re-implement this functionality in a different language. This Pulumi program is based on the Talos documentation for standing up a cluster on AWS.

The Pulumi program has four major sections:

  1. First, it creates the underlying base infrastructure Continue reading

IDC Makes Ebullient AI Spending Forecast Out To 2029

Ever since Nvidia reported its most recent financial results, where company co-founder and chief executive officer Jensen Huang said that there would be somewhere between $3 trillion and $4 trillion in spending on AI between now and the end of the decade, we have been on the prowl for any market research that backs up this claim or is its source. …

IDC Makes Ebullient AI Spending Forecast Out To 2029 was written by Timothy Prickett Morgan at The Next Platform.

Bringing Node.js HTTP servers to Cloudflare Workers

We’re making it easier to run your Node.js applications on Cloudflare Workers by adding support for the node:http client and server APIs. This significant addition brings familiar Node.js HTTP interfaces to the edge, enabling you to deploy existing Express.js, Koa, and other Node.js applications globally with zero cold starts, automatic scaling, and significantly lower latency for your users — all without rewriting your codebase. Whether you're looking to migrate legacy applications to a modern serverless platform or build new ones using the APIs you already know, you can now leverage Workers' global network while maintaining your existing development patterns and frameworks.

The Challenge: Node.js-style HTTP in a Serverless Environment

Cloudflare Workers operate in a unique serverless environment where direct tcp connection isn't available. Instead, all networking operations are fully managed by specialized services outside the Workers runtime itself — systems like our Open Egress Router (OER) and Pingora that handle connection pooling, keeping connections warm, managing egress IPs, and all the complex networking details. This means as a developer, you don't need to worry about TLS negotiation, connection management, or network optimization — it's all handled for you automatically.

This fully-managed approach is actually why Continue reading

Measuring Explicit Congestion Notification

I've always thought that the TCP protocol was the heart of the ingenuity that is the Internet. TCP is a flow control protocol that strives to produce both fair efficient outcomes, both for each TCP session, but for the networ4k as well. The essential feedback signal used by TCP is congestion-based packet loss, but this isn't the only approach. Another approach lies in enrolling the aassistance of the network's routers, and use packet marking instead of loss to signal to the TCP end hosts that network congestion is taking place. This form of signalling, Explicit Congestion Notification is explored in this article, as well as the outcomes of a measurement exercise to establish just how widely we used this alternativer form of congestion signalling.
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