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  • Human Infrastructure 441: Hack Your DAC, Working Around LLM Limitations, and More

Human Infrastructure 441: Hack Your DAC, Working Around LLM Limitations, and More

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Robin Young, Ethan Banks & Drew Conry-Murray
March 26, 2026

THIS WEEK’S MUST-READ BLOGS 🤓

Christian had some 10Gbps DACs lying around, so he plugged them into 25Gbps ports. But they stuck to 10Gbps. To his thinking, the DACs are just copper, so why the speed limitation? Well, there’s an EEPROM that stores the speed the cable assembly is capable of functioning at, and that value gets signaled.

Okay, so what if you could reprogram the EEPROM? It turns out that with the right DAC, interface, and software, you can make your 10Gbps DAC talk 25Gbps! There are many possible gotchas (including not all DACs are of a quality to carry higher speeds), but Christian shares his experience in detail. DIY FTW. - Ethan

Considering the age of IPv6, the data is grim, in my opinion. The blog leads off as follows. “We probed the 100,000 most-linked web hosts for IPv6 support using the Common Crawl Web Graph. Only 36.9% are fully reachable over IPv6, with adoption ranging from 71% among the top 100 to 32% in the long tail.”

We’ve been frustrated by this at Packet Pushers. We don’t have a data center of our own—we’re a small company that lives in the cloud. We lean hard into various cloud services & a CDN to deliver podcasts, this newsletter, our website, and so on. A great many SaaS products simply don’t offer IPv6 at all. You’d think IPv6 would be ubiquitous, but in fact you’ve got to seek it out. - Ethan

Instructor Kevin Wallace breaks down what’s different in Cisco’s 1.2 release of the CCNP ENCOR exam. He says that wireless is gone, but there’s more multicast. Plus there’s lots of Cisco product rebranding to confuse you. Kevin also says not to freak out if you’ve been working on v1.1 material—1.2 isn’t that different. If you like to buy video training, Kevin’s got an ENCOR v1.2 course on offer. - Ethan

Gábor Kis-Hegedüs talks about how to think about what LLMs actually do under the hood, including why they are sometimes confidently wrong. With that foundation, you can understand LLMs’ limitations, how to make good use of them, and why they can’t replace humans.

This a technical but approachable article that’s clearly written and avoids generalizations like thinking or reasoning. Gábor instead explains what’s actually happening with databases, math, statistics, and predictions. If hype articles and ignorant YouTubers farming for clicks with their AI hot takes drive you mad, you’ll appreciate the content here. - Ethan

This blog does two things. First, it shares a neat tool where you can upload Wireshark packet captures of wireless traffic to get visualizations. Second, it describes the adventures of the author vibe-coding this tool into existence. He’s not a programmer, so he shares resources and lessons learned for how to use AI to help write tools. - Drew 

MORE BLOGS

  1. HPE Aruba Networking AOS-CX BGP Soft Clear - Major Network

  2. netlab: Switch to Lab Directory After an SSH Session Loss - ipSpace

  3. Convergence Takes Off in the Datacenter (RoCE, RDMA, PFC, ECN) - Systems Approach

  4. Is the Future of AI Local? (Apple’s betting on it) - Tom Bedor’s Blog

Build a data foundation your automation can grow on
When you start a network automation project, it's tempting to grab popular tools and go. You’ll land some quick wins. But 18 months from now, you’ll either be scaling smoothly…or bumping up against painful gaps and constraints.

The future you face comes down to the data foundation you pick at the start.

Infrahub from OpsMill is a data management platform purpose-built to power network automation and AIOps. A fully extensible schema manages anything you want. Version control and change management are core features, not plugins.

When you build on that data foundation, the possibilities open up fast: scalable provisioning, self-service catalogs, durable lifecycle management, context-enriched agentic workflows.

Try the live Infrahub sandbox or grab the open-source version on GitHub. Your future self will thank you.

TECH NEWS 📣

This update from the US Federal Communications Commission spawned many headlines such as the snarky one above. Note that the ban is about residential routers and not all routers. Most of the concerns raised come from the practicality of such a ban. Where, exactly, will Americans get their home routers from? An interesting question with some possible answers the article explores. - Ethan

IPv4 address space is valuable. Really valuable. If you’ve got v4 address space, it’s worth something between $20 & $40 per address. If you’re AWS, address space represents not only a valuable asset but also recurring revenue.

This will be the situation for a long time. As the piece concludes, ”The “uncomfortable truth” isn’t that IPv6 is failing; it’s that the “dual-stack” era is going to be significantly longer and more expensive than early proponents forecasted. For the enterprise customer, the message is clear: the road to the cloud is paved in IPv4, but the tolls are getting higher.”

Indeed. - Ethan

Turns out some people don’t want VCF 9—either the cost or complexity. Others can’t leave the VMware ecosystem, even if they wanted to. Just too hard to do that migration. They’ll end up running VCF 9 when their 8.x family support runs out. - Ethan

Microsoft has revealed that it made an oopsie. For nine months in 2025, Microsoft failed to send Entra ID logins to its Microsoft Defender for Cloud Applications (MDA) service. What’s the big deal? Login activity is often a key signal that something’s amiss. For companies who pay to use MDA for security monitoring, that’s nine months of fundamental information that wasn’t included. The article notes that Microsoft did log the Entra activity, but you had to know it wasn’t showing up and go and find it in the Entra portal itself.

Aside from raising questions about Microsoft product quality (an evergreen issue), the article says Microsoft has now created more work for the customers of this service, noting “...organizations that conducted security investigations, compliance reviews, or audit responses during the affected period using MDA data absolutely have follow-up work to do. They need to assess whether any conclusions drawn from MDA sign-in data during those nine months were affected by the gap.” - Drew

MORE NEWS

FOR THE LULZ 🤣

RIP Chuck Norris. Born March 10, 1940. Died March 19, 2026.
The Internet’s greatest meme.

RESEARCH & RESOURCES 📒

From the README. “A terminal UI for Ansible — manage inventories, run playbooks, stream logs. Inspired by lazydocker. lazyansible wraps Ansible in a panel-based TUI that shows inventory, playbooks, per-host status, and streaming logs — all in one terminal window, all keyboard-driven.” - Ethan

netboot.xyz - your favorite operating systems in one place
https://netboot.xyz

From the docs. “netboot.xyz lets you PXE boot various operating system installers or utilities from a single tool over the network. This lets you use one media for many types of operating systems or tools. The iPXE project is used to provide a user friendly menu from within the BIOS that lets you easily choose the operating system you want along with any specific types of versions or bootable flags.

You can remote attach the ISO to servers, set it up as a rescue option in Grub, or even set up your home network to boot to it by default so that it's always available.” - Ethan

Wi-Fi nerd Eva Santos launched a newsletter. Eva’s pretty awesome. You should probably subscribe to her newsletter. I just did. - Ethan

MORE RESOURCES

Failover worked. The network didn’t.

In this episode of Cyber Confessionals, a hardware failure triggered failover to a backup firewall that looked ready — but wasn’t.

Routing and NAT were incomplete.
Traffic broke.
And police officers in the field lost access to critical systems.

A real story about why “high availability” doesn’t mean what you think it does.

The voice is synthetic, but the panic is real. Real engineers, real outages, total anonymity. This is Cyber Confessionals. 

UPCOMING LIVE EVENTS 🍕🍻

A curated list of near-future meatspace events of interest to network engineers. Sometimes a Packet Pusher or two will be there (noted below).

Subscribe to events.packetpushers.net in your calendar software.

APRIL 2026

Wi-Co Finland
9 April | Helsinki, Finland

TORNOG1 | Toronto Network Operators Group
13 April | Toronto, Canada (Ethan attending)

Wi-Fi World Congress USA 2026
13 - 15 April | Mountain View, CA

Wi-Co Philadelphia
16 April | Philadelphia, PA

Wi-Fi Design Day 2026
16 April | London, UK

Wi-Co Toronto
22 April | Toronto, Canada

Wi-Co Frankfurt
29 April | Frankfurt, Germany

MAY 2026

Extreme Connect 2026 
4 - 7 May | Orlando, FL (Packet Pushers will be there)

NLNAM Meetup 2 | NL Network Automation Meetup
13 May | Alphen aan den Rijn, Netherlands

Wi-Co Brussels
21 May | Brussels, Belgium

(NH)NUG | New Hampshire Networking User Group (USNUA)
27 May | TBD, NH (Ethan co-organizing)

Wi-Co Memphis
29 May | Memphis, TN

Cisco Live US
31 May - 4 June | Las Vegas, NV (Packet Pushers likely)

INDUSTRY BLOGS & VENDOR ANNOUNCEMENTS 💬 

Julia Gervasi highlights the strengths of CPUs, GPUs, and TPUs in the AI ecosystem. She focuses particularly on the history of GPUs, explaining why the mathematics involved in artificial intelligence performs very well on GPUs originally designed for gaming. - Ethan

Doug Madory, Director of Internet Analysis at Kentik, walks through a series of charts and data points, correlating real world events with Internet traffic changes in and out of Iran. While it’s interesting from an engineering perspective, the human impact is the real point of this analysis. Lots of people who really, really need the Internet right now have had it taken from them.

Doug keeps these people in mind, as I hope we all do. “For the people in Iran, the inability to communicate compounds the horror they are experiencing. According to the latest Filterwatch report from Miaan Group, communication failures, coupled with physical bombardment, have made daily survival and safety coordination increasingly precarious for millions of civilians digitally stranded during a critical humanitarian crisis. Consequently, citizens have been forced into a predatory black market for data where costs are prohibitively high. Without common modes of communication, they cannot reach out to loved ones to confirm they are safe, nor tell the world what they are experiencing.” - Ethan

“Resilience” was one of the buzzwords of RSA Conference 2026. As threat actors find ways to use AI tools to accelerate attacks, organizations also need to become adept at identifying attack signals, responding swiftly, and building IT systems that can quickly recover from damages. This report from consultancy PWC notes “the advantage belongs to organisations that treat security not as a fixed set of controls, but as a high-performance system — governing identity at speed, validating trust at every turn, and aligning cyber, business, and geopolitical strategy to stay ahead of an ever-faster field.” - Drew 

MORE INDUSTRY NOISES

DYSTOPIA IRL 🐙

TOO MANY LINKS WOULD NEVER BE ENOUGH 🐳

LAST LAUGH 😆