- There’s no layer-2 address in Fibre Channel frames (because FC is routing not bridging);
- Why is the multicast bit lowest bit (0x01) in first byte on Ethernet but highest bit (0x80) on Token Ring or FDDI;
- How some NIC manufacturers never got the memo on what OUI really means.
Remember the Cloud Models, Layers and Responsibilities video by Matthias Luft? He continued his introduction of cloud services with Cloud Services Hierarchy, explained the differences between infrastructure, platform, function and software as a service, and concluded with a there’s no free lunch message.
Here’s one of the secrets to AWS’s unprecedented scale and financial success: they figured out very early on that some services are not worth delivering. Most everyone else believes in building snowflake single-customer solutions to solve imaginary problems, effectively losing money while doing so.
After a brief coverage of the theoretical aspects of network addressing, it’s time to pay a brief visit to the early data-link-layer addressing solutions, from one address per datagram/frame (SDLC, HDLC) and ignore this address (PPP) to no address on P2P links (SLIP).
If you’re a regular reader of this blog, you’ve probably realized there’s still need for networking in public clouds, and mastering it requires slightly different set of skills. What could you as a networking engineer to get fluent in this different world? I collected a few hints in the last video in Introduction to Cloud Computing webinar.
In May 2021, Javier Antich ran a great webinar explaining the principles of Artificial Intelligence and Machine learning and how they apply (or not) to networking.
He started with a brief overview of AI/ML hype that should help you understand why there’s a bit of a difference between self-driving cars (not that we got there) and self-driving networks.
You wouldn’t believe the intricate network designs I created decades ago until I learned that having an uninterrupted sleep is worth more than proving I can get the impossible to work (see also: using EBGP instead of IGP in a 4-node data center fabric).
Once I started valuing my free time, I tried to design things to be as simple as possible. However, as my friend Nicola Modena once said, “Consultants must propose new technologies because they must be seen as bringing innovation,” and we all know complexity sells. Go figure.
After explaining the basics of (network) names, addresses and routes, I wasted a few minutes of everyone’s time discussing the theoretical aspects of layered addressing, and then got back to practical issues like address scopes, namespaces, and address provisioning.
The video ends with a simple (and unappreciated) truth: if you have a point-to-point link between two nodes you don’t need data-link-layer addresses. The consequences of that fact are left as an exercise for the viewer (or you can wait till the next video ;)
Even though you need plenty of traditional networking constructs to deploy a complex application stack in a public cloud (packet filters, firewalls, load balancers, VPN, BGP…), once you start digging deep into the bowels of public cloud virtual networking, you’ll find out it’s significantly different from the traditional Ethernet+IP implementations common in enterprise data centers.
For an overview of the differences watch the Public Cloud Networking Is Different video (part of Introduction to Cloud Computing webinar), for more details start with AWS Networking 101 and Azure Networking 101 blog posts, and continue with corresponding cloud networking webinars.
Whenever someone is promising a miracle solution, it’s probably due to them working in marketing or having no clue what they’re talking about (or both)… or it might be another case of adding another layer of abstraction and pretending the problems disappeared because you can’t see them anymore.
The name of a resource indicates what we seek, an address indicates where it is, and a route tells us how to get there.
You might wonder when that document was written… it’s from January 1978. They got it absolutely right 42 years ago, and we completely messed it up in the meantime with the crazy ideas of making IP addresses resource identifiers.
In the previous video in the Switching, Routing and Bridging section of How Networks Really Work webinar we compared transparent bridging with IP routing. Not surprisingly (given my well-known bias toward stable solutions) I recommended using IP routing as much as possible, but there are still people out there pushing large-scale transparent bridging solutions.
In today’s video we’ll look at some of the supposed use cases and stable solutions you could use instead of stretching a virtual thick yellow cable halfway across a continent.
In June 2020, a friend of mine asked me to do a short presentation on lessons learned during my 35 years of being a networking engineer. It went reasonably well, so I decided to turn it into a webinar, starting with regardless of what the disruptive marketers tell you, technology still matters.