HW089: Spectrum Analysis and Vibe Coding
Keith sits down with Kjetil Hansen to explore spectrum analysis and vibe coding for wireless networking tools. They also discuss building custom tools, using AI for 3D network modeling, and how Kjetil uses OpenIntent in his projects. Episode Links: Kjetil Hansen’s Website Kjetil Hansen on YouTubeHS143: Why We Don’t Believe in Self-Healing AI (Sponsored)
Everyone is talking about autonomous AI for network operations. But in critical infrastructure, is removing the human really the right goal? In this sponsored episode, Johna and John welcome BackBox CEO Rekha Shenoy and VP of Products and Engineering Richard Phillips to discuss the risks of blind autonomy, where AI can go wrong, why human... Read more »
PP127: Network Configuration and State Visibility at Scale with Unimus (Sponsored)
Today’s Packet Protector is a sponsored show that sits very nicely at the networking/security intersection. Our sponsor is NetCore, which makes the Unimus network configuration management software. Unimus supports network automation, configuration management and backup, change management, and auditing and compliance. We dive into how Unimus provides visibility into both the running config and the... Read more »EVPN with SR-MPLS Core
After a long journey, we finally we got to the final scenario in my ITNOG10 Segment Routing workshop: EVPN services over an SR-MPLS core.
I used the same lab topology as in the previous services-focused scenarios blog post, replacing two PE-to-host subnets with a stretched VLAN.
EVPN over SR-MPLS core
Ansible Installation
It has been over 5 years since I wasted far too much of my life on my Ansible build fabric pet project. I got it doing what I set out to do, but there was so much Python fudging under the hood I figured I may as well move away from Ansible and go all in on Python (and Nornir). I thought it was high time to give Ansible another go and see if it has got any less painful.
Tech Bytes: Why Beaver Excavating Tapped Firezone for WireGuard-Powered VPN (Sponsored)
Today on the Tech Bytes podcast we talk VPNs. Our sponsor is Firezone, which offers a secure remote access solution built on Wireguard. But instead of just hearing from Firezone, we talk with a customer. Our guest is Daniel Caruso, IT Network and Systems Administrator at Beaver Excavating, a construction firm headquartered in Canton, OH.... Read more »NB592: AWS Recommends UAE Migration; FCC Wants More Spectrum for Satellite Broadband
Take a Network Break! We start with listener follow-up on Arista’s vulnerability reporting, and Cisco ISE takes center stage for our Red Alert. Then we dive into EVA Networks, a startup touting ephemeral network connectivity to minimize risks of persistent network access, why AWS is recommending customers relocate workloads away from its data centers in... Read more »BGP EVPN in SONiC – Part I: L2VNI for Inter-Switch VLAN Extension
Introduction
The previous chapter explained how to build
an IPv6-only multi-ASN Clos fabric where IPv4 prefixes can be advertised with
IPv6 link-local next hops.
In this chapter, we extend VLAN 10 between
Leaf-101 and Leaf-102 using BGP EVPN as the control plane and VXLAN as the data
plane.
Figure 7-1 shows the main building blocks
required to provide this functionality. The IP underlay, where leaf and spine
switches use IPv6 link-local addresses for eBGP peering, has already been
configured in the previous chapter. Loopback0 is used only as the BGP Router ID
and is not advertised to any peer.
The IP address of Loopback1, in turn, is used
as the VXLAN Tunnel Endpoint (VTEP) address. Each switch therefore advertises
its Loopback1 IP address using BGP IPv4 Unicast so that the VTEP addresses are
reachable across the fabric. This address identifies the local VTEP in the EVPN
control plane and is used as the BGP next hop for EVPN routes. A VXLAN packet
sent to a remote VTEP uses the remote VTEP address as the destination address
in the outer IP header.
Each extended VLAN is mapped to an L2VNI (Layer-2 VXLAN Network Identifier). In Figure 7-1, VLAN 10 Continue reading
netlab 26.09: Syslog, More DNS, Netmiko
netlab release 26.09 brings more network services goodies:
- The services module supports Syslog clients and servers.
- DNS and Syslog are implemented on most supported platforms.
Other new features include:
- The new netmiko device configuration mode for virtual machines
- Generic prefix sets that simplify writing ACL rules and prefix lists
Real-time elephant flow monitoring in AI / ML fabrics
Calculations:
- Packet Size (4KB): 4,096 bytes × 8 bits/byte = 32,768 bits
- Line Rate Packet Speed: 400,000,000,000 bits/sec ÷ 32,768 bits = 12,207,031.25 packets per second
- Average Time per Packet: 1 ÷ 12,207,031.25 pps = 81.92 nanoseconds
- Average Sample Interval: 81.92 nanoseconds × 100,000 = 0.008192 seconds (8.192 ms)
- Default 1400 byte sFlow datagrams fills with 6 packet samples (each sample containing 128 bytes of packet header + metadata)
- Time taken to fill the datagram with 6 samples given by the Erlang-6 distribution
- Mean: 49.15ms, Median: 46.45ms, Standard Deviation: 20.07ms
- sFlow agent required to send UDP datagram as soon as buffer fills
- Network transit delay is less than 1ms and can be ignored
- Maximum delay is 1000ms. sFlow agent required to send datagram within 1 second of the first record being added
The net result is that an sFlow analyzer will receive streaming telemetry describing an elephant flow within 100ms of the Continue reading
Bot-free self-hosted analytics with GoatCounter on NixOS
In 2016, I removed Google Analytics from this blog to avoid being complicit in feeding the biggest machine for harvesting personal data. Instead, I relied on GoAccess to analyze my server logs.1 For the past couple of years, the statistics have made no sense, despite my attempts to filter bots: AI scrapers inflate the number of visitors to around 2,000 per day. Eventually, I settled on GoatCounter, an open-source, privacy-friendly web analytics platform. I replaced the JavaScript client to filter bots more aggressively and added a CSS fallback. To improve reliability, I implemented a local proxy running on each of the five web servers serving this blog. The rest of this post details how these pieces fit together and how I deploy them on NixOS. ❄️
Why GoatCounter?
GoatCounter does not collect personal data: instead of storing the reader’s IP address or relying on cookies, it creates a session identifier valid for 8 hours from the user agent and the IP address. Its feature set is modest but sufficient for a blog. If Continue reading
The magic of OFDM
I’ve been playing a bit with OFDM in software defined radio lately. And after watching a video that wasn’t even close to correct, I thought I’d write down my understanding in a blog post. I wouldn’t call myself an expert, so worst case someone will correct me, and I’m happy to be corrected.
In my experiments with OFDM my initial goal is understanding, so e.g. I won’t blindly use some hierarchical GNU Radio block.
I/Q and the actual analog signal
I think that in order to internalize OFDM, we first need to remind ourselves how a purely “real” wave becomes a complex number, at a high level.
The real signal is a value that’s a function of time. Glossing over details, this is not feasible for most of our signals, as we would need to provide a new value to the transmitter at a rate twice as high as the highest frequency we care about. For 2.4GHz experiments, we’d need 4.8 billion samples per second.
Quadrature sampling allows us to represent a slice of bandwidth at a manageable rate. We can then provide the I/Q data to hardware, instructing it to hold that “until further notice”. Continue reading
Hedge 319: Using AI
AI is everywhere. While there are many questions about whether AI is a bubble, the ethics of AI, and the cultural impact of AI, in this episode of the Hedge Mike Bushong joins Eyvonne, Tom, and Russ to talk about how network engineers can use AI. Are some use cases better than others? Are there pitfalls network engineers should avoid? Listen in and find out.
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HN842: How Network Engineers Can Prepare for a Post-Quantum World
Q-Day signals the public emergence of a cryptographically relevant quantum computer that can break public key encryption. The date of Q-Day is unknown but the tech industry is making preparations now. Bill Dockery joins Drew and guest host Scott Robohn to dig into Post Quantum Cryptography (PQC), what network engineers need to know to test... Read more »TNO073: Network Automation Forum: From Simple Survey to Global Community
In this crossover episode, Scott invites William Collins and Eric Chou to do the hosting so he and Network Automation Forum (NAF) cofounder Chris Grundemann can discuss how their community emerged from a simple question: Why haven’t we seen full adoption of network automation? They discuss the growth of AutoCon and how its practitioner-focused, vendor-neutral... Read more »Why networking is different for AI Data Centers
This article discusses the necessity for rethinking data center networking in the context of AI. Traditional designs based on traffic averages and oversubscription do not apply, as AI workloads produce massive, synchronized "elephant" flows, necessitating non-blocking architectures and emphasizing metrics like job completion time and GPU utilization over conventional measures.
The post Why networking is different for AI Data Centers appeared first on /overlaid.
IPB208: IPv6 Address Management Is Broken
Traditional IPAM and DDI tools struggle to handle IPv6 at scale because they were originally designed around IPv4. Today Ed and Tom examine the visibility challenges posed by SLAAC addresses, broken DNS integrations, and massive prefix allocations. They also share potential solutions and strategies for enterprise IPv6 deployment. AdSpot Sponsor: Megaport If you’re supporting cloud... Read more »N4N064: A Gentle Introduction to Border Gateway Protocol (BGP)
Border Gateway Protocol (BGP), the routing protocol of the global internet, is finding uses in all sorts of places in 2026 beyond internet routing. It’s a huge topic. Large books have been written about BGP and its related technologies, so Ethan and Holly are here with a gentle introduction to BGP. They break down what... Read more »Sunsetting netlab Vagrant/libvirt provider
When I started the netlab project, Vagrant was the go-to tool if you wanted to build a virtual environment described in a text configuration file (an idea popularized as infrastructure-as-code). It wasn’t ideal for what we were doing, but a tool rarely does a great job when used far away from its intended use case.
netlab initially supported Vagrant with VirtualBox, quickly adding support for KVM/libvirt through the vagrant-libvirt plugin. Life was good… until it wasn’t.