Packet Pushers: The New Network Challenge

A couple of weeks ago Scott Morris, Ethan Banks, and I sat down to talk about a project I’ve been working on for a while—a different way of looking at reaching for and showing your skills as a network engineer.

Today’s Heavy Networking explores ideas for designing a new networking certification program. The concept is built around a network design challenge that focuses on broad, systems-oriented knowledge.

You can listen over at Packet Pushers, or download the show directly here.

Measuring the Core

This last week I was a guest on the TechSequences podcast with Leslie and Alexa discussing the centralization of the routed infrastructure in the ‘net. When that episode posts, I’ll cross post it here (but, of course, you should really just subscribe to their podcast, as they always have interesting guests—I’ll have Leslie and Alexa on the Hedge at some point, as well). The topic is related to this post on CircleID about the death of transit, which was a reaction to Geoff Huston’s article on the death of transit some time before.

All that to say… while reading through some research papers this week, I ran into a recent (2018) paper where Carisimo et al. try out different ways of measuring which autonomous systems belong to the “core” of the ‘net. They went about this by taking a set of AS’ “everyone” acknowledges to be “part of the core,” and then trying to find some measurement that successfully describes something all of them have in common.

The result is the k-metric, which measures the connectivity of an AS’ peers. If an AS has peers who are just as connected as they are, then k-metric is high. Otherwise, the k-metric is low. It does make sense this measure would be able to pick out “core” AS’, because it picks out the set of most highly interconnected AS’ in the ‘net.

Once they determined the k-metric is a good way to determine which AS’ are in the core of the ‘net, they calculated the membership of the core over time. Their graph is below.

The way the chart is laid out is a little difficult to see, but the green is transit providers and the blue is content providers. Certainly enough, the percentage of content providers in the core of the ‘net, in terms of sheer connectivity, has increased over time. These same content providers now account for some 80% (or more?) of the traffic on the ‘net. All this means is the centralization of content is visible in objective measurements, so its a real thing. Content providers are currently “only” 20% of the core but given their traffic levels this is a much bigger deal than it seems. There are many parts of the world where the population or access density is not high enough for large content providers to justify building out so they touch the last mile. If communities build out last mile optical networks, however, its likely these large content providers will consume ever-larger percentages of the “core” AS’.

Troubleshooting Theory Live Webinar: May 8

Troubleshooting is a fundamental skill for all network engineers, from the least to most experienced. However, there is little material on correct and efficient troubleshooting techniques in a network engineering context, and no (apparent) live training in this area. Some chapters in books exist (such as the Computer Networking Problems and Solutions, published in December 2017), and some presentations in Cisco Live, but the level of coverage for this critical skill is far below what engineers working in the field to develop solid troubleshooting skills.

Working from Home: Myth and Reality

The last few weeks have seen a massive shift towards working from home because of the various “stay at home” orders being put in place around the world—a trend I consider healthy in the larger scheme of things. Of course, there has also been an avalanche of “tips for working from home” articles. I figured I’d add my own to the pile.

A bit of background—I first started working from home regularly around twenty years ago, while on the global Escalation Team at Cisco. I started by working from home one day a week, to focus on projects, slowly increasing over time, ultimately working from the office one day a week when I transitioned to the Deployment and Architecture Team. Since that team was scattered all over the world—we had a few folks in Raleigh, two in Reading (England), one Brussels, one in Scott’s Valley, and one or two in the San Jose (California) area, we had to learn to work together remotely if we had any hope of being effective. Further, we (as a family) have home-schooled “all the way through”—my oldest daughter is nearing the end of high school, currently overlapping with some college work. I have always had the entire family at home most of the time.

So, forthwith, some thoughts and experiences, including some you might not have ever heard, and some myth busting along the way.

Probably the most common piece of advice I hear is you should set a schedule and stick to it. On the other hand, the most common thing people like about working from home is the flexibility of the schedule. Somehow no-one ever seems to put these two together and say “hey, one of these things just doesn’t belong here!” (remember that old song, courtesy of public television). When you are working from home, setting a fixed schedule similar to being in an office is precisely the wrong thing to do. This is a myth.

Instead, what you should do is to try to intentionally carve out several hours a day of “quiet time” to get things done. This might be different times in the day for your house, and its not likely to be consistent on a daily, weekly, or monthly basis. The most productive times of the day are going to shift—get used to it. Most of my family are late sleepers or tend to get up in the morning and do “quiet things,” so the mornings tend to be much more productive for me than the afternoons. This isn’t always true; sometimes the evenings are quieter. There are few days, however, when there isn’t some quiet time during each day.

The key to scheduling is to plan project work for these quiet times, whenever they happen to be. Given the schedule of my house, I get up in the morning and immediately dive into project work. I leave email and reading RSS feeds for the afternoon, because I know I won’t be able to concentrate as well during those time. On the other hand, I try not to get frustrated if my routine is broken up—just put off the project work until the time when it is quiet. Roll with the punches, rather than trying to punch against the rolls, when it comes to time. The only fixed point should be to think about how many hours of quiet time you need per week and figure out how to get it.

Don’t worry about having 8 hours solid, or whatever. Take breaks to eat lunch with family or friends. Take breaks to have a cup of hot liquid. Run out to the store in the afternoon. Exercise in the middle of the day. Take advantage of the flexible schedule to break work up into multiple pieces, rather than being glued to an office desk for 8 hours, regardless of your productivity level through that time. This is not the office—don’t act like it is.

The second most common piece of advice I hear is find a space and stick to it. This is not a myth—it is absolutely true. I have a table in the basement in one place, and a dedicated room as an office in another. When we go on vacation as a family, I either make certain to have a large enough room to have space to work, or I scope out someplace I can “set up shop” someplace in the hotel. Space is just that important.

Sometimes you hear get the right equipment. This, also, I can attest to. Tools, however, are a bit of an obsession for me; I will spend hours perfecting a tool, even if it does not, ultimately, save me as much time as I originally thought. I am a stickler for the right monitory, chair, desk space, footrests, and keyboards. I play with lighting endlessly; I have finally settled on a setup with a dim monitor, dim room lighting, bias lighting behind the monitor, and a backlit keyboard. I’ve concluded that reducing the sheer amount of light being poured into my eyes, across the board, helps increase the amount of time I can keep working. Some people prefer two monitor setups—I prefer a single large monitor (31in right now). I don’t use a mouse, but a Wacom tablet. I’ve recently added an air purifier to my office space—I think this makes a difference. I don’t have a trash can close by—its useful to force myself to get up every now and again. Your physical environment is a matter of personal preference but pay attention to it. This will probably have as much impact on your productivity as anything else you do.

Overall, don’t let other people tell you what tools are the best. I’ve been told for more years I can remember that I should stop using Microsoft Word for long-form writing. You should switch to markdown, you should switch to Scrivener, you should use FocusWriter… Well, whatever. I’ve written … around 13 books, and I have two more in progress. I’ve written thousands of blog posts and articles. I’ve written thousands of pages of research papers, and I’m currently working on my dissertation. All in Microsoft Word. I’ve tried other tools, but ultimately I’ve found that Word, with my own customized interface settings, to be just as fast or faster than anything else I’ve worked with.

One thing you almost never hear is a team change. If one person is remote, act like everyone is. There is nothing more disruptive, or less useful, than having one person on the phone while everyone else is sitting in a conference room. If one person has to dial in, everyone should dial in. Setting up times to “just hang out” as a “meeting” is also sometimes helpful. If you have a fully remote team, dedicate “in real life” time to doing things you cannot do on meetings, and dedicate meeting time to things you cannot do through email, a chat app, or some other means.

Finally, some people are neat nicks while others are sloppy. I tend towards the extreme neat end of things, arranging even my virtual desktop “just so” (I actually do not have any icons on my desktop at all, and I’m very picky about what I put in my start menu and/or command bar).

The key thing is, I think, to pay attention to what helps and what doesn’t, and not be afraid to experiment to find a better way.

Live Webinar: How the Internet Really Works

I’m teaching a live webinar, How the Internet Really Works, next Friday on You can register here. I’ve expanded this from a three-hour webinar to a four-hour webinar, which means I’m adding about 30’ish slides, and redoing a few bits and pieces of the presentation. In fact, I’m revamping a few of my webinars, creating two new ones, rebuilding two of them as livelessons, and working on some new material with Ethan as well.

Please join me this next Friday—first time with the new slides, so it should be interesting.