27 posts tagged with "Azure"

I happened upon the diagram below within the pages on default outbound internet access and it seemed a little counterintuitive. The decision flow seems to suggest that a VM will use the egress IP of a NAT gateway preferably over an assigned PIP.

This is here primarily as a reminder to me; a note for when I need this again. You may already know this or you may find this useful to learn this.

Most people think of Azure Public Load Balancer as that thing that spreads web traffic across multiple servers. Fair enough - that's what it does best. But it's actually a Swiss Army knife for network address translation that can solve some tricky connectivity problems you might not expect.

I have found that Azure networking has been designed to be familiar to network engineers, even though a lot of the logical constructs are based on smoke and mirrors they largely behave like the things we're used to; a great example being the VNet that doesn't exist or the load balancer that is also a figment of our imagination. AWS Networking on the other hands seems to have been created by a bunch of developers high on peyote who thought they knew better than everyone else. This is why it took me a few years to pass the AWS Advanced Networking exam but only a few days to pass the Azure Networking Engineering Associate exam.

So here's something I definitely didn't see coming when I started my blog, I just got the email that I've been awarded Microsoft Most Valuable Professional (MVP) status for Cloud and Datacenter Management - On-Premises Networking.

In my previous post, I shared some basic latency tests across Azure networks. The results were pretty predictable: the closer things are physically, the faster they communicate. Not exactly groundbreaking.

But when I expanded my testing to include longer distances and different connection methods, I stumbled onto something genuinely surprising: PrivateLink connections can actually be faster than direct VNET peering - sometimes significantly so.

I had a look recently at Azure Subnet Peering which was mostly undocumented at the time except for a blog post by Jose Moreno, one of the gurus of Azure Networking.

When I set out to explore network latency in Azure, I had a simple goal: to understand how physical distance affects performance. After all, we've all heard that farther apart means slower connections. But I wanted specifics - exactly how much slower? And how consistent is that performance? I also wanted to see how long lived TCP connections performed across the Azure network.

I'm sharing what I've learned from my first round of tests, setting a baseline that we can build on later.

I like to point out to people that it's easier to train a network person on cloud than it is to train a cloud person on networks. It's a glib generalisation but it holds true for the most part because there is so much to networking that comes from history and quite a lot of grounding that a seasoned network engineer or architect will already understand. A big chunk of the AWS and Azure networking certification covers BGP and that's one of the reasons they are considered quite hard for some but quite easy for others. BGP is a topic that many very experienced network engineers in enterprise networking can get through their entire career without touching, but for those who operate at scale or work with MSP and telco networks it's bread and butter.

I've been exploring a pretty niche feature preview that you can find documented here. In some cases, you might want to expand the size of a subnet, but if you have a constrained IP space, you might not have contiguous space available. Here's what I've found you can do.

I found an interesting little field hidden in plain sight in Microsoft documentation. A clever chap recently said this to me: 'if you can figure out what problem the engineers were trying to solve then it makes it easier to understand why the product works the way it does'.

When you create a VNet in Azure or a VPC in AWS, you need to allocate a CIDR range for your subnets. There are key differences between these cloud providers when expanding networks, which can create challenges. Knowing these rules from the start helps you plan your CIDR ranges better. I'll start with what's similar across AWS and Azure, then look at the differences.

Make it make sense​

I will always be a network engineer, and that means some words have very specific meanings that have taken root in my soul. The terminology within ExpressRoute has bothered me for ages, and when speaking to a few people, I found that I'm not the only one who finds it unintuitive. To me, a circuit is a single link, but to Microsoft, a circuit is the pair of links and the associated peerings! Two thumbs up to that, Microsoft, or rather in your own language 'one ExpressRoute thumb'.

There seems to be an obsession over on Reddit about the Mandela Effect which was named after a collective but strongly held false memory that the eponymous Nelson Mandela had died in prison in the '80s. It seems that our minds can play tricks on us and sometimes things which we clearly remember turn out to be a shared fantasy. I feel a little like this about those weird two weeks in about April 2021, in midst of the 'rona years, where everyone on LinkedIn got Aviatrix certification for free and then shared it with their contacts so that they too could benefit from a free certification in an emerging technology vendor's product. The reason I'm not sure if it's a Mandela Effect is that I don't really think I've heard of anyone since who has actually used that certification for anything other than to pad out their Credly.

Counting prefixes the same way my wife counts my mistakes​

Anyone who has accidentally advertised too many prefixes and watched their ISP BGP peerings collapse (I'm looking at you, BT) knows that prefix limits are a common safeguard in networking. While exploring anycast configurations in Azure, I carefully noted the official Route Server prefix limit of 1,000 routes. However, I recently discovered something far more interesting in the fine print about how Azure actually calculates this limit.

A good friend of mine is taking his AZ-700 next week and asked me a few questions about Azure Traffic Manager, Azure Front Door and the WAF capabilities in Azure. Some of the questions in his practice exams were a bit confusing. As he's not only a good friend but also the kind chap who proof reads a lot of these blog posts, I thought I'd try to explain what the options are and when you'd use them. On a side note, if you fancy talking to a top tier network guy and all-round nice fella, I thoroughly recommend you look up Zain Khan.

Introduction​

When working with Azure cloud networking, I've noticed certain limitations, particularly around DNS capabilities for private networks. In this post, I'll explore an unconventional approach: using Amazon Route 53 to address some of Azure's DNS limitations. While this might seem controversial, it offers interesting solutions to two specific challenges: cross-region failover for private resources and closest-instance routing within private networks.

I had a conversation today about sharding in Azure. It's a fairly well-known thing in AWS but it's employed in Azure as well and has some important implications for workload placement in a few specific use cases. In this post, I'll explore the concept of AZ sharding, its implications for cross-subscription services, and techniques for mapping physical AZs to achieve optimal performance.

I've recently been exploring one of the sneaky under-the-radar features that could be a game changer in the near future: Azure Subnet Peering. This is a feature that's already there in the API but not really documented or productised yet.

Let's explore solutions for global site load balancing.

The Mystery Begins​

The reason I fell down the rabbit hole with regard to finding my public IP was because of a section in an old Azure networking book my friend was reading. It said:

To allow Azure internal communication between resources in Virtual Networks and Azure services, Azure assigns public IP addresses to VMs, which identifies them internally. Let's call these public IP addresses AzPIP (this is an unofficial abbreviation). You can check the Azure internal Public IP address bound to the VM with the command dig TXT short o-o.myaddr.google.com.

My Perspective​

After 20+ years implementing network and cloud infrastructure across finance, retail, healthcare, and public sector, I've seen a clear pattern: cloud success strongly links to an organisation's readiness. Yet surprisingly few organisations do thorough readiness checks before starting their cloud journey.

By far the stand out session for me at Ignite this year was Unveiling the latest in Azure Networking for a secure connected cloud | BRK240 which covered a lot of interesting announcements and enhancements in Azure Networking. Many of these are particularly relevant for projects I'm working on right now.

I wrote an article about a rather neat solution for global application delivery in Azure via anycast, however there are some limitations which exist to prevent transit routing in Azure that I'd like to discuss further.

Is it as great as Microsoft says or as bad as the customers say?​

When Microsoft unveiled Azure Virtual WAN, it was heralded as a revolutionary solution for simplifying complex networking scenarios in the cloud. The vision was compelling: a comprehensive service that would streamline branch connectivity to Azure, enable seamless hub-and-spoke architectures, provide automated routing with simplified security, and offer easy integration with SD-WAN appliances. For organisations grappling with the intricacies of cloud networking, this sounded like a panacea and I know plenty who fell for it. However, as many have discovered, the reality of implementing and managing Virtual WAN has proven far more challenging than initially anticipated.

Not all FQDN filters are built the same.

The glue you never knew you needed.

Introduction​

I've seen many organisations face the challenge of securely exposing services across various network boundaries. Whether it's sharing resources during a merger, providing services to customers, or managing internal shared services, the need for secure, private connections is paramount. Azure Private Link service is a powerful solution to these challenges, offering a way to enable private connectivity to services in Azure across organisational and networking boundaries without exposure to the public internet.