Russ

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Worth Reading: Automatically detecting peering infrastructure outages

Given the high concentration of interconnections, the uptime of peering infrastructures is crucial for overlay Internet applications. Facilities and IXPs strive to meet Service Level Agreements (SLAs) of ‘five nines’ (five minutes downtime per year), and ‘four nines’ (50 minutes downtime per year). However, outages still occur due to power failures, human errors, attacks, and natural disasters. —Vasileios Giotsas @APNIC

The Universal Fat Tree

Have you ever wondered why spine-and-leaf networks are the “standard” for data center networks? While the answer has a lot to do with trial and error, it turns out there is also a mathematical reason the fat-tree spine-and-leaf is is used almost universally. There often is some mathematical reason for the decisions made in engineering, although we rarely explore those reasons. If it seems to work, there is probably a reason.

The fat-tree design is explored in a paper published in 2015 (available here at the ACM, and now added to my “classic papers” page so there is a local copy as well), using a novel technique to not only explore why the spine-and-leaf fat-tree is so flexible, but even what the ideal ratio of network capacity is at each stage. The idea begins with this basic concept: one kind of network topology can be emulated on top of another physical topology. For instance, you can emulate a toroid topology on top of a hierarchical network, or a spine-and-leaf on top of of hypercube, etc. To use terms engineers are familiar with in a slightly different way, let’s call the physical topology the underlay, and the emulated topology the overlay. Continue reading

Weekend Reads 042718: Mostly Security and Privacy

The Internet Corporation for Assigned Names and Numbers (ICANN) launched the Uniform Rapid Suspension System (URS) (2013) in anticipation of the marketing of new gTLDs that became available from November 2013. It is one of four new rights protection mechanisms (RPMs) designed to combat cybersquatting. —Gerald M. Levine @CircleID

Digital attackers are targeting organizations in the energy sector like never before. For example, just a few weeks ago, the FBI and Department of Homeland Security issued a joint report describing a massive Russian hacking campaign to infiltrate America’s critical infrastructure. In a first, the US government publicly blamed Russia’s government for attacks on energy infrastructure. —Ray Lepina @tripwire

About a decade ago, Kaminsky proved that vulnerabilities of the DNS can be exploited. If the DNS is corrupt (for instance by ‘cache poisoning’), the end user can be directed to a malicious website. This can be risky when sensitive (personal) information is exchanged, or a financial transaction is done. Mail security is also tied to (the security of) the DNS. A network attacker can spoof the DNS records of a mail server, to redirect mail connections to a malicious server. —Rene Bakker @APNIC

When we must depend on a system, not Continue reading

On the Web: Openfabric at IPspace

I was over at ipspace to talk to Ivan and several other folks about openfabric. This is one of those situations where… Well, the algorithm openfabric uses to calculate fabric location has changed slightly in the last week. Welcome to the world of networking technology. ?

As always, we started with the “what’s wrong with what we have right now, like using BGP as a better IGP” question, resulting in “BGP is becoming the trash can of the Internet”. You can probably guess the next set of intro questions: “Do we need policies and traffic engineering in a high-speed data center fabric?” Finally, we got to discussing OpenFabric, starting with how OpenFabric uses link-state database to modify IS-IS flooding behavior and thus reduces the total amount of flooding in a data center fabric. Next step: how do you know where it’s safe to reduce flooding? You have to figure out whether you’re a leaf or spine, and there are two ways in OpenFabric to solve that challenge.

Whatever is vOLT-HA?

Many network engineers find the entire world of telecom to be confusing—especially as papers are peppered with a lot of acronyms. If any part of the networking world is more obsessed with acronyms than any other, the telecom world, where the traditional phone line, subscriber access, and network engineering collide, reigns as the “king of the hill.”

Recently, while looking at some documentation for the CORD project, which stands for Central Office Rearchitected as a Data Center, I ran across an acronym I had not seen before—vOLT-HA. An acronym with a dash in the middle—impressive! But what is, exactly? To get there, we must begin in the beginning, with a PON.

There are two kinds of optical networks in the world, Active Optical Networks (AONs), and Passive Optical Networks (PONs). The primary difference between the two is whether the optical gear used to build the network amplifies (or even electronically rebuilds, or repeats) the optical signal as it passes through. In AONs, optical signals are amplified, while ins PONs, optical signals are not amplified. This means that in a PON, the optical equipment can be said to be passive, in that it does not modify the optical signal in Continue reading

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