Public Videos: Network Connectivity and Graph Theory
In May 2024, I made public the first half of the Network Connectivity and Graph Theory videos by Rachel Traylor.
Now, you can also enjoy the second part of the webinar without a valid ipSpace.net account; it describes trees, spanning trees, and the Spanning Tree Protocol. Enjoy!
Optimizing OSPF RFC Access with Serper API and Large Language Models
Disclaimer: All Writings And Opinions Are My Own And Are Interpreted Solely From My Understanding. Please Contact The Concerned Support Teams For A Professional Opinion, As Technology And Features Change Rapidly.
This series of blog posts will focus on one feature at a time to simplify understanding.
At this point, ChatGPT—or any Large Language Model (LLM)—needs no introduction. I’ve been exploring GPTs with relative success, and I’ve found that API interaction makes them even more effective.
But how can we turn this into a workflow, even a simple one? What are our use cases and advantages? For simplicity, we’ll use the OpenAI API rather than open-source, self-hosted LLMs like Meta’s Llama.
Let’s consider an example: searching for all OSPF-related RFCs on the web. Technically, we’ll use a popular search engine, but to do this programmatically, I’ll use Serper. You can find more details at https://serper.dev. Serper is a powerful search API that allows developers to programmatically access search engine results. It provides a simple interface to retrieve structured data from search queries, making it easier to integrate search functionality into applications and workflows.
Let’s build the first building block and try to fetch results using Serper. When you sign Continue reading
Network CI/CD – Configuration Management with Napalm and Nornir
Hi all, welcome back to part 4 of the Network CI/CD blog series. So far, we've covered the purpose of a Network CI/CD pipeline, the problems it solves for Network Engineers, and how to set up GitLab, including creating projects, installing runners, and understanding GitLab executors. We also looked at how to use GitLab variables to securely hide secrets.
In this part, we'll explore how to manage a campus network using Nornir and Napalm and deploy configurations through a CI/CD pipeline. Let's get to it!
Network CI/CD Pipeline - What’s the Point?
Hi all, welcome to the ‘Network CI/CD’ blog series. To kick things off, let’s ask the question, “Why do we even need a CI/CD pipeline for networks?” Instead of diving straight into technical definitions
Suresh Vina
As I mentioned previously, I'm not a CI/CD expert at all and I'm still learning. The reason for creating this series is to share what I learn with the community. The pipeline we are building is far from perfect, but that's okay. The goal here is to create a simple pipeline that works and then build upon it as we go. This way, you can start small and gradually Continue reading
HN748: How AI and HPC Are Changing Data Center Networks
On today’s episode of Heavy Networking, Rob Sherwood joins us to discuss the impact that High Performance Computing (HPC)and artificial intelligence computing are having on data center network design. It’s not just a story about leaf/spine architecture. That’s the boring part. There’s also power and cooling issues, massive bandwidth requirements, and changes in how we... Read more »TNO002: How Simplification Helps MSPs Scale
Simplification is the theme of today’s episode. Host Scott Robohn and guest Jack Maxfield explore the operational impacts of simplification for a Managed Service Provider (MSP). They discuss the challenges of managing multi-vendor environments and how to use templating and tools to simplify the management process. Proactive client communication and the integration of network and... Read more »Repost: BGP, EVPN, VXLAN, or SRv6?
Did you know that some vendors use the ancient MPLS/VPN (RFC 4364) control plane when implementing L3VPN with SRv6?
That’s just one of the unexpected tidbits I discovered when explaining why you can’t compare BGP, EVPN, and SRv6.
Network CI/CD Pipeline – GitLab Variables
Hi all, welcome back to our Network CI/CD blog series. In the previous posts, we covered what CI/CD is and why you need it for Network Automation. We also covered GitLab basics and how to set up your first pipeline. In this post, we’ll look into how to keep your credentials secure by hiding them from the repository and using GitLab variables. Let’s get to it!
GitLab Variables
In GitLab CI/CD, variables play an important role in managing dynamic values throughout your pipeline. These variables can store anything from environment-specific settings to sensitive information like credentials. By using variables, you can easily manage and change values without hardcoding them in your scripts or playbooks.
GitLab provides a secure way to store sensitive data such as passwords or API tokens. You can define these variables in your project’s Settings > CI/CD > Variables section, and they will be securely injected into your pipeline during runtime.
If you recall, in our previous examples, we had the username and password hardcoded in the Ansible variables file. This is not secure at all, and you should never expose sensitive information like credentials directly in your repository. By using GitLab variables, you can securely Continue reading
Hedge 242: The Myth of the Coder
In the early days of computer programming, some thought there was a difference between a coder and a programmer. Did this division ever really exist, and are there similar divisions in network engineering?
NetPicker – A Great Network Configuration Backup Tool
Hi everyone, welcome back to the Packetswitch blog. Today, we're going to look into NetPicker, a tool that not only performs Network Compliance Tests but also takes backups of your network devices. In this post, we'll walk you through downloading and installing NetPicker, adding devices, taking backups, and setting up backup schedules.
Is It Free?
As of September 2024, according to NetPicker’s pricing page, there’s a ‘Free for Life’ plan that allows unlimited backup of your device configurations and unlimited automated tests for up to 10 devices. This means you can manage backups for all of your devices without spending a penny. If you need to run tests on more than 10 devices, you’ll likely need to consider purchasing a license.
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Disclaimer - NetPicker sponsors my blog as of writing this post. However, the opinions expressed here are entirely my own, and they have not influenced the content of this article.
Download and Installation
To get started with NetPicker, navigate to their website and fill out the form with your name and email. After you complete this step, you'll receive an email with detailed installation instructions. You have two main options for installation.
- Download an OVA Continue reading
IPB159: IPv6 Basics – Router Advertisements
Our series on IPv6 basics continues with Router Advertisements (RAs) within the Neighbor Discovery Protocol. We look at how hosts bootstrap onto a network using ICMPv6, discuss the timing of sending out an RA, and then cover the configuration of RAs, including key flags and options. We also talk about the importance of understanding the... Read more »Wireshark tid-bit: Looking for the smoking gun
It’s not always the network which is at fault but it is usually the network that is the assumed culprit. Wireshark can be a vital tool when troubleshooting difficult scenarios or prove that the network is not root cause. The purpose of this post is to ask questions and promote out of the box thinking […]EVPN Designs: Scaling IBGP with Route Reflectors
In the previous blog posts, we explored the simplest possible IBGP-based EVPN design and tried to figure out whether BGP route reflectors do more harm than good. Ignoring that tiny detail for the moment, let’s see how we could add route reflectors to our leaf-and-spine fabric.
As before, this is the fabric we’re working with:
Bringing insights into TCP resets and timeouts to Cloudflare Radar
Cloudflare handles over 60 million HTTP requests per second globally, with approximately 70% received over TCP connections (the remaining are QUIC/UDP). Ideally, every new TCP connection to Cloudflare would carry at least one request that results in a successful data exchange, but that is far from the truth. In reality, we find that, globally, approximately 20% of new TCP connections to Cloudflare’s servers time out or are closed with a TCP “abort” message either before any request can be completed or immediately after an initial request.
This post explores those connections that, for various reasons, appear to our servers to have been halted unexpectedly before any useful data exchange occurs. Our work reveals that while connections are normally ended by clients, they can also be closed due to third-party interference. Today we’re excited to launch a new dashboard and API endpoint on Cloudflare Radar that shows a near real-time view of TCP connections to Cloudflare’s network that terminate within the first 10 ingress packets due to resets or timeouts, which we’ll refer to as anomalous TCP connections in this post. Analyzing this anomalous behavior provides insights into scanning, connection tampering, DoS attacks, connectivity issues, and other behaviors.
A global assessment of third-party connection tampering
Have you ever made a phone call, only to have the call cut as soon as it is answered, with no obvious reason or explanation? This analogy is the starting point for understanding connection tampering on the Internet and its impact.
We have found that 20 percent of all Internet connections are abruptly closed before any useful data can be exchanged. Essentially, every fifth call is cut before being used. As with a phone call, it can be challenging for one or both parties to know what happened. Was it a faulty connection? Did the person on the other end of the line hang up? Did a third party intervene to stop the call?
On the Internet, Cloudflare is in a unique position to help figure out when a third party may have played a role. Our global network allows us to identify patterns that suggest that an external party may have intentionally tampered with a connection to prevent content from being accessed. Although they are often hard to decipher, the ways connections are abruptly closed give clues to what might have happened. Sources of tampering generally do not try to hide their actions, which leaves hints of Continue reading
MSS, MSS Clamping, PMTUD, and MTU
Maximum Segment Size (MSS) and MSS clamping are concepts that can be confusing. How do they relate to the MTU (Maximum Transmission Unit)? Before we setup a lab to demonstrate these concepts, let’s give some background. Note that this entire post assumes a maximum frame size of 1518 bytes, the original Ethernet definition, and does not cover jumbo frames.
Ethernet frame
Almost all interfaces today are Ethernet. The original 802.3 standard from 1985 defined the minimum size- and maximum size frame as the following:
- minFrameSize – 64 octets.
- maxFrameSize – 1518 octets.
With a maximum frame size of 1518 octets (bytes), that leaves 1500 bytes of payload as the Ethernet frame adds 18 bytes, 14 bytes of header and 4 bytes of trailer. The Ethernet frame is shown below:
IP header
An IPv4 IP header adds at least 20 bytes to the frame. The IPv4 header is shown below:
Note that more than 20 bytes can be used if the header has IP options. With no options in the IP header, there’s 1480 bytes remaining for the L4 protocol such as UDP or TCP.
TCP header
TCP also adds a minimum of 20 bytes, meaning that the maximum payload Continue reading
D2DO250: The Realities of Responsible Disclosure in the Cloud
Cloud security and responsible disclosure are the focus of today’s conversation with guest Kat Traxler. Kat shares her insights on identifying vulnerabilities in cloud services, particularly Google Cloud, and the importance of curiosity in her research. The episode explores the role of bug bounty programs and the shift towards issuing CVEs for cloud vulnerabilities. Lastly,... Read more »Routing Table and BGP RIB on SR Linux
Ages ago, I described how “traditional” network operating systems used the BGP Routing Information Base (BGP RIB), the system routing table (RIB), and the forwarding table (FIB). Here’s the TL&DR:
- Routes received from BGP neighbors are stored in BGP RIB.
- Routes redistributed into BGP from other protocols are (re)created in the BGP RIB.
- BGP selects the best routes in BGP RIB using its convoluted set of rules.
- Best routes from the BGP RIB are advertised to BGP neighbors
- Best routes from the BGP RIB compete (based on their administrative distance) against routes from other routing protocols to enter the IP routing table (system RIB)
- Routes from the system RIB are copied into FIB after their next hops are fully evaluated (a process that might involve multiple recursive lookups).