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The Hedge #74: Brian Keys and the Complexity of User Interfaces
Crossing from the domain of test pilots to the domain of network engineering might seem like a large leap indeed—but user interfaces and their tradeoffs are common across physical and virtual spaces. Brian Keys, Eyvonne Sharp, Tom Ammon, and Russ White as we start with user interfaces and move into a wider discussion around attitudes and beliefs in the network engineering world.
You Can Always Add Another Layer of Indirection (RFC1925, Rule 6a)
Many within the network engineering community have heard of the OSI seven-layer model, and some may have heard of the Recursive Internet Architecture (RINA) model. The truth is, however, that while protocol designers may talk about these things and network designers study them, very few networks today are built using any of these models. What is often used instead is what might be called the Infinitely Layered Functional Indirection (ILFI) model of network engineering. In this model, nothing is solved at a particular layer of the network if it can be moved to another layer, whether successfully or not.
For instance, Ethernet is the physical and data link layer of choice over almost all types of physical medium, including optical and copper. No new type of physical transport layer (other than wireless) can succeed unless if can be described as “Ethernet” in some regard or another, much like almost no new networking software can success unless it has a Command Line Interface (CLI) similar to the one a particular vendor developed some twenty years ago. It’s not that these things are necessarily better, but they are well-known.
Ethernet, however, goes far beyond providing physical layer connectivity. Because many applications rely Continue reading
On Using the Right Word
A while back, I was sitting in a meeting where the presenter described switching from a “traditional, hierarchical data center fabric” to a spine-and-leaf (while drawing CLOS, in all capital letters, on the whiteboard). He pointed out that the spine-and-leaf design is simpler because it only has two tiers rather than three.
There is so much wrong with this I almost winced in physical pain. Traditional hierarchical designs are not fabrics. Spine-and-leaf fabrics are not CLOS, but Clos, fabrics. Clos fabrics have three stages, not two—even if we draw them “folded” so you only see two apparent levels to the fabric. In fact, all spine-and-leaf fabrics always have an odd number of stages, and they are stages, not tiers.
More recently, I heard someone talking about an operating system that was built using microservices. I thought—“that would be at neat trick.” To build something with microservices does not just mean a piece of software using modules—this would be modular application (or operating system) design. Microservices architectures break the application up into the most basic components possible and then scale each kind of component out (rather than up) by spinning new copies of each service as needed. I cannot imagine Continue reading
The Hedge #73: Daniel Teycheney and Open Source in Networking
Combining, or stitching together, open source projects to build something unique for your network is becoming more common. What does this look like in the real world? What are some of the positive and negative aspects of building things this way? How do open source projects interact with the commercial world? Daniel Teycheney joins Tom Ammon, Jett Tantsura, and Russ White to discuss open source software in networking, particularly around network monitoring and management.
Rethinking BGP on the DC Fabric (part 5)
BGP is widely used as an IGP in the underlay of modern DC fabrics. This series argues this is not the best long-term solution to the problem of routing in fabrics because BGP is not ideal for this use case. This post will consider the potential harm we are doing to the larger Internet by pressing BGP into a role it was not originally designed to fulfill—an underlay protocol or an IGP.
My last post described the kinds of configuration required to make BGP work on a DC fabric—it turns out that the configuration of each BGP speaker on the fabric is close to unique. It is possible to automate configuring each speaker—but it would be better if we could get closer to autonomic operation.
To move BGP closer to autonomic operation in a DC fabric, there are several things we can do. First, we can allow a BGP speaker to peer with any other BGP speaker it receives an open message from—this is often called promiscuous mode. While each router in the fabric will still need to be configured with the right autonomous system, at least we won’t need to configure the correct peers on each router (including the Continue reading
The Hedge #72: Lisa Caywood and Marketectures
The open source world is not much different than the commercial world in terms of building marketectures rather than useable software—largely because open source projects still rely on sources of funding and material support to build and maintain a product. Many times, however, the focus on these marketectures get in the way of real work. Join Tom Ammon, Russ White, and Lisa Caywood as we discuss the problem of marketectures and the broader world of open source software.
Technologies that Didn’t: Directory Services
One of the most important features of the Network Operating Systems, like Banyan Vines and Novell Netware, available in the middle of the 1980’s was their integrated directory system. These directory systems allowed for the automatic discovery of many different kinds of devices attached to a network, such as printers, servers, and computers. Printers, of course, were the important item in this list, because printers have always been the bane of the network administrator’s existence. An example of one such system, an early version of Active Directory, is shown in the illustration below.
Users, devices and resources, such as file mounts, were stored in a tree. The root of the tree was (generally) the organization. There were Organizational Units (OUs) under this root. Users and devices could belong to an OU, and be given access to devices and services in other OUs through a fairly simple drag and drop, or GUI based checkbox style interface. These systems were highly developed, making it fairly easy to find any sort of resource, including email addresses of other uses in the organization, services such as shared filers, and—yes—even printers.
The original system of this kind was Banyan’s Streetalk, which did not have the Continue reading
Rethinking BGP on the DC Fabric (part 4)
Before I continue, I want to remind you what the purpose of this little series of posts is. The point is not to convince you to never use BGP in the DC underlay ever again. There’s a lot of BGP deployed out there, and there are lot of tools that assume BGP in the underlay. I doubt any of that is going to change. The point is to make you stop and think!
Why are we deploying BGP in this way? Is this the right long-term solution? Should we, as a community, be rethinking our desire to use BGP for everything? Are we just “following the crowd” because … well … we think it’s what the “cool kids” are doing, or because “following the crowd” is what we always seem to do?
In my last post, I argued that BGP converges much more slowly than the other options available for the DC fabric underlay control plane. The pushback I received was two-fold. First, the overlay converges fast enough; the underlay convergence time does not really factor into overall convergence time. Second, there are ways to fix things.
If the first pushback is always true—the speed of the underlay control plane Continue reading
Book Updates 0221
Someone recently asked me to suggest a list of books on thinking skills; I figured others might be interested in the list, as well, so … I decided to post it here. Further, I’ve added a few books to my “recommended book list” here on rule11; I thought I’d point those out, as well. My first suggestion, of course, is that if you want to improve your thinking skills, read. I don’t just mean technical stuff, I mean all over the place, in the form of books, and a lot.
So, forthwith, some more things to read.
Thinking Books
- Algorithms in a Nutshell
- The Inquiring Mind
- What Tech Calls Thinking
- Unintended Features
- The Elements of Reasoning
- Deep Work
- Being Logical
Recently Added Books
- From Counterculture to Cyberculture
- Escape from Reason
- The Rise and Triumph of the Modern Self
- Death in the City
- Rational Cybersecurity
- The Age of Access
- Curing Mad Truths
- Called to Freedom
You can find my list of recommended books here, and my goodreads profile, which lists a lot of the books I’ve read, I’m currently reading, and plan to read, here.
The Hedge #71: Nick Russo and Automating Productivity
When we think of automation—and more broadly tooling—we tend to think of automating the configuration, monitoring, and (possibly) the monitoring of a network. On the other hand, a friend once observed that when interviewing coders, the first thing he asked was about the tools they had developed and used for making themselves more efficient. This “self-tooling” process turns out to be important not just to be more efficient at work, but to use time more effectively in general. Join Nick Russo, Eyvonne Sharp, Tom Ammon, and Russ White as we discuss self-tooling.
History of FARNT with Laura Breeden
FARNT was a regional consortium of smaller network operators that eventually helped drive the adoption of TCP/IP and the global Internet, as well as helping efforts to commercialize Internet access. Join Donald Sharp and Russ White as Laura Breeden discusses the origins of FARNT, it’s importance in the adoption of early Internet technologies, and the many hurdles regional network operators had to overcome.
Laura is now the Board Chair at the National Digital Inclusion Alliance.
On the ‘net: The Art of Conviction
I was recently a guest on The Art of Conviction podcast, where we covered a bit of my background, some of the challenges I’ve faced in getting where I am, and then we moved into a discussion around my recently finished dissertation. I’m working to find places to publish more in the area of worldview and culture; I’ll point to those here as I can find a “home” for that side of my life.
You can find the recording here.
Beyond my episode, The Art of Conviction is a fascinating podcast; you should really subscribe and listen in.
Rethinking BGP on the DC Fabric (part 3)
The fist post on this topic considered some basic definitions and the reasons why I am writing this series of posts. The second considered the convergence speed of BGP on a dense topology such as a DC fabric, and what mechanisms we normally use to improve BGP’s convergence speed. This post considers some of the objections to slow convergence speed—convergence speed is not important, and ECMP with high fanouts will take care of any convergence speed issues. The network below will be used for this discussion.
Two servers are connected to this five-stage butterfly: S1 and S2 Assume, for a moment, that some service is running on both S1 and S2. This service is configured in active-active mode, with all data synchronized between the servers. If some fabric device, such as C7, fails, traffic destined to either S1 or S2 across that device will be very quickly (within tens of milliseconds) rerouted through some other device, probably C6, to reach the same destination. This will happen no matter what routing protocol is being used in the underlay control plane—so why does BGP’s convergence speed matter? Further, if these services are running in the overlay, or they are designed to discover Continue reading
The Hedge #70: FR Routing Update
FR Routing is a widely used and supported open source routing stack. In this episode of the Hedge, Alistair Woodman, Quentin Young, Donald Sharp, Tom Ammon, and Russ White discuss recent updates, additions to the CI/CD system, the release process, and operating system support. If you’re looking for a good open source, containerized routing stack for everything from route servers to DC fabrics and labbing to production, you should check out FR Routing.