Russ

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IPv6 Standardization

The IETF published RFC8200 last week, which officially makes IPv6 an Internet Standard. While this move was a long time coming—IPv6 has now reached about 20% deployment—a more interesting question is: what has changed since RFC2460, which was a draft standard, was published in 2013? After all, the point of moving from the experimental to the draft standard to the internet standard states is to learn more about the protocol as it operates on the wire, and to make changes to improve deployability and performance.

Where would you look to determine what these changes might be? The IETF draft tracker tool, of course. If you look at the data tracker page for RFC8200, you will find a tab called history. From there, you have the option of looking at the revision differences, as shown below.

When you click on the wdiff button, you will see something like this—

In this case, I went back to the original version of the RFC2460bis draft (which just means the draft was designed to replace RFC2460). There are earlier versions of this draft from before it was accepted as a working group document, but even this comparison should give you some idea of the Continue reading

Administravia 20170703

Just a short note: I’ve updated the sixty book section of the site with a new plugin designed to keep track of book libraries. Along the way, I’ve added an Amazon affiliate code, so maybe I can buy a cup of hot chocolate and a piece of banana nut bread at some point in the future. ? The look should really be a bit nicer, though, and it is easier to add books to this system than manually adding them as I was doing before.

Remember that the idea of sixty books is not that there are actually 60 books on the list, but rather this is what I read in an average year—and hence what I am challenging you to work up to.

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Random Thoughts on Grey Failures and Scale

I have used the example of increasing paths to the point where the control plane converges more slowly, impacting convergence, hence increasing the Mean Time to Repair, to show that too much redundancy can actually reduce overall network availability. Many engineers I’ve talked to balk at this idea, because it seems hard to believe that adding another link could, in fact, impact routing protocol convergence in such a way. I ran across a paper a while back that provides a different kind of example about the trade-off around redundancy in a network, but I never got around to actually reading the entire paper and trying to figure out how it fits in.

In Gray Failure: The Achilles’ Heel of Cloud-Scale Systems, the authors argue that one of the main problems with building a cloud system is with grey failures—when a router fails only some of the time, or drops (or delays) only some small percentage of the traffic. The example given is—

  • A single service must collect information from many other services on the network to complete a particular operation
  • Each of these information collection operations represent a single transaction carried across the network
  • The more transactions there are, the Continue reading
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