Russ

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Responding to Readers: Questions on Microloops

Two different readers, in two different forums, asked me some excellent questions about some older posts on mircoloops. Unfortunately I didn’t take down the names or forums when I noted the questions, but you know who you are! For this discussion, use the network show below.

In this network, assume all link costs are one, and the destination is the 100::/64 Ipv6 address connected to A at the top. To review, a microloop will form in this network when the A->B link fails:

  1. B will learn about the link failure
  2. B will send an updated router LSP or LSA towards D, with the A->B link removed
  3. At about the same time, B will recalculate its best path to 100::/64, so its routing and forwarding tables now point towards D as the best path
  4. D, in the meantime, receives the updated information, runs SPF, and installs the new routing information into its forwarding table, with the new path pointing towards E

Between the third and fourth steps, B will be using D as its best path, while D is using B as its best path. Hence the microloop. The first question about microloops was—

Would BFD help prevent the microloop (or Continue reading

Weekend Reads 030218:

It’s been said that software is “eating the world.” More and more, critical systems that were once controlled mechanically, or by people, are coming to depend on code. This was perhaps never clearer than in the summer of 2015, when on a single day, United Airlines grounded its fleet because of a problem with its departure-management system; trading was suspended on the New York Stock Exchange after an upgrade; the front page of The Wall Street Journal’s website crashed; and Seattle’s 911 system went down again, this time because a different router failed. The simultaneous failure of so many software systems smelled at first of a coordinated cyberattack. Almost more frightening was the realization, late in the day, that it was just a coincidence. —James Somers @The Atlantic

The charges, and the confirmation that the Russians had used social media in an attempt to influence the 2016 election, is likely to fuel the call for government regulation of Twitter, Facebook and other social media outlets. When tweets and posts can hurt democracy, America should do something, right? Wrong. —Paul Levinson @Connecting

As we start to connect durable goods such as cars, medical devices, and electricity meters to the Internet, Continue reading

Reaction: Billing by the Hour

A very common mistake I see among engineers of all stripes is a failure to fully appreciate the value of time—both what it is worth, and how to make your time more valuable.

What I normally see is something like this—I should be making $x/hour, because I have this specific experience, or that specific skill set. This focus on hourly pay, however, is actually counter productive. For instance, I recently ran across an article in a publication for graphic designers and illustrators (a world I have followed since I lived it in many years ago)—

Billing by the hour is the most popular pricing method across the world in most industries. Of course, there are many web designers/developers out there who make a great living by using the hourly billing method, but in my opinion, value-based billing is far better than hourly billing. —Kyle Prinsloo @Web Designer Depot

To begin, what does Kyle mean when he says to “bill by value” rather than billing by the hour? Once, when I went into a lawyers office, I noticed he had a sign on the wall that said, “Lawyers don’t charge by the bullet.” The point the lawyer was making Continue reading

Weekend Reads 022318: Copyright, walls, and botnets

Rejecting years of settled precedent, a federal court in New York has ruled [PDF] that you could infringe copyright simply by embedding a tweet in a web page. Even worse, the logic of the ruling applies to all in-line linking, not just embedding tweets. If adopted by other courts, this legally and technically misguided decision would threaten millions of ordinary Internet users with infringement liability. —Daniel Nazer @EFF

Security advances throughout the centuries have been mostly technical adjustments in response to evolving weaponry. Fortification — the art and science of protecting a place by imposing a barrier between you and an enemy — is as ancient as humanity. From the standpoint of theory, however, there is very little about modern network or airport security that could not be learned from a 17th century artillery manual. That should trouble us more than it does. —Jack Anderson

Akamai’s Fourth Quarter, 2017 State of the Internet, was released today in which it states that the analysis of more than 7.3 trillion bot requests per month has found a sharp increase in the threat of credential abuse, with more than 40 percent of login attempts being malicious. Additionally, the report warns DDoS attacks Continue reading

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