C 001. Intro into the IPv4/IPv6 Application Support from the Software/System Point of View.
Dear friend,
Being a long-time network engineer, I’ve seen (and done) it all: talking about about IPv6, designing and implementing IPv6 in production service providers and data center networks, holly wars IPv6 vs IPv4, industries saying they aren’t going to use IPv6 ever, and many others. For some network engineers, it could be even quite an “innovation” project (I clearly remember some senior person told me back in 2018 that introduction of IPv6 is an innovation; quite a statement in the 20-years anniversary of IPv6). But today I want to talk about it from a different angle.
How Is Network Relevant for Software?
In many cases every day we rely on the software, which works over Internet: whatever you need to buy or sell some goods, order a table in your favorite cafe, book ticket to train to visit your friends. Connected world is around us and, if for whatever reason it breaks, our life immediately becomes much more difficult. That’s because the applications rely on the Internet and their capability to provide you the service depends on their capabilities to connect from your smartphone or laptop to the application servers. And this capability is significantly affected by Continue reading
Why Distributedness is a Measure of Digital Maturity
Digital maturity takes a lot of work and a variety of skill sets. That’s why multi-cloud networking (MCN) exists as a market and why it continues to gain traction.ARP Details Behind the Scenes
When figuring out how unnumbered IPv4 interfaces work, Daniel Dib asked an interesting question: How does ARP work when the source and destination IPv4 address are not in the same segment (as is usually the case when using unnumbered interfaces)?
TL&DR: ARP doesn’t care about subnets. If the TCP/IP stack needs to find a MAC address of a node it thinks is adjacent, ARP does its best, no matter what.
ARP Details Behind the Scenes
When figuring out how unnumbered IPv4 interfaces work, Daniel Dib asked an interesting question: How does ARP work when the source and destination IPv4 address are not in the same segment (as is usually the case when using unnumbered interfaces)?
TL&DR: ARP doesn’t care about subnets. If the TCP/IP stack needs to find a MAC address of a node it thinks is adjacent, ARP does its best, no matter what.
The Network Times 2023-08-27 09:59:00
Available at Leanpub and Amazon
About This Book
A modern application typically comprises several modules, each assigned specific roles and responsibilities within the system. Application architecture governs the interactions and communications between these modules and users. One prevalent architecture is the three-tier architecture, encompassing the Presentation, Application, and Data tiers. This book explains how you can build a secure and scalable networking environment for your applications running in Microsoft Azure. Besides a basic introduction to Microsoft Azure, the book explains various solutions for Virtual Machines Internet Access, connectivity, security, and scalability perspectives.
Azure Basics: You will learn the hierarchy of Microsoft Azure datacenters, i.e., how a group of physical datacenters forms an Availability Zone within the Azure Region. Besides, you learn how to create a Virtual Network (VNet), divide it into subnets, and deploy Virtual Machines (VM). You will also learn how the subnet in Azure differs from the subnet in traditional networks.
Internet Access: Depending on the role of the application, VMs have different Internet access requirements. Typically, front-end VMs in the presentation tier/DMZ are visible on the Internet, allowing external hosts to initiate connections. VMs in the Application and Data tiers are rarely accessible from Continue reading
Case Study: NGINX + Certbot with Ansible
About this series
In the distant past (to be precise, in November of 2009) I wrote a little piece of automation together with my buddy Paul, called PaPHosting. The goal was to be able to configure common attributes like servername, config files, webserver and DNS configs in a consistent way, tracked in Subversion. By the way despite this project deriving its name from the first two authors, our mutual buddy Jeroen also started using it, and has written lots of additional cool stuff in the repo, as well as helped to move from Subversion to Git a few years ago.
Michael DeHaan [ref] founded Ansible in 2012, and by then our little PaPHosting project, which was written as a set of bash scripts, had sufficiently solved our automation needs. But, as is the case with most home-grown systems, over time I kept on seeing more and more interesting features and integrations emerge, solid documentation, large user group, and eventually I had to reconsider our 1.5K LOC of Bash and ~16.5K files under maintenance, and in the end, I settled on Ansible.
commit c986260040df5a9bf24bef6bfc28e1f3fa4392ed
Author: Pim van Pelt <[email protected]>
Date: Thu Nov 26 23:13:21 2009 +0000
Continue readingChoosing the Underlay Protocol in a VXLAN Network
When building a VXLAN network, what are the considerations for choosing the underlay protocol such as OSPF, IS-IS, or BGP? You obviously want the design to be supported by your vendor of choice. Your staff should also be able to support the design. Although I think it’s reasonable to expect from a Network Engineer that they have some level of knowledge in OSPF and BGP and that this should not be the main deciding factor. Let’s dive into the different protocols and walk through their characteristics and how they can be used as underlay protocols in a VXLAN network. I will compare OSPF to BGP as ISIS basically provides all the benefits of OSPF with some additional ones, but with less support from vendors, and it’s a protocol less known by most Engineers.
OSPF
Protocol overview – OSPF is a link state protocol that builds a Link State Database (LSDB) and runs the Shortest Path First (SPF) algorithm based on Dijkstra’s work to calculate the shortest path. It relies on flooding Link State Advertisements (LSAs). All routers in an area need an identical LSDB.
Ajacencies and transmitting protocol packets – OSPF transmits packets over IP in IP protocol 89. It Continue reading
SEC To CEOs: Report Your Breaches
The SEC now requires publicly traded companies to report "material" security incidents. But what does "material" mean and how might this new requirement affect infosec practices at these companies?
The post SEC To CEOs: Report Your Breaches appeared first on Packet Pushers.
Networking Is Fast Enough
Without looking up the specs, can you tell me the PHY differences between Gigabit Ethernet and 10GbE? How about 40GbE and 800GbE? Other than the numbers being different do you know how things change? Do you honestly care? Likewise for Wi-Fi 6, 6E, and 7. Can you tell me how the spectrum changes affect you or why the QAM changes are so important? Or do you want those technologies simply because the numbers are bigger?
The more time I spend in the networking space the more I realize that we’ve come to a comfortable point with our technology. You could call it a wall but that provides negative connotations to things. Most of our end-user Ethernet connectivity is gigabit. Sure, there are the occasional 10GbE cards for desktop workstations that do lots of heavy lifting for video editing or more specialized workflows like medical imaging. The rest of the world has old fashioned 1000Mb connections based on 802.3z ratified in 1998.
Wireless is similar. You’re probably running on a Wi-Fi 5 (802.11ac) or Wi-Fi 6 (802.11ax) access point right now. If you’re running on 11ac you might even be connected using Wi-Fi 4 (802.11n) if you’re Continue reading
Heavy Networking 696: EVPN Fundamentals (And Some VXLAN) With Tony Bourke
EVPN/VXLAN is our topic on today's Heavy Networking. What is it? What’s it for? Should you deploy it? Since you’ve probably already got a network, how do you add EVPN to it? Do you need special hardware? How does EVPN impact your security design? And what are the fundamentals? Our guest with the answers is IT instructor Tony Bourke.
The post Heavy Networking 696: EVPN Fundamentals (And Some VXLAN) With Tony Bourke appeared first on Packet Pushers.