Research: P Fat Trees

Link speeds in data center fabrics continue to climb, with 10g, 25g, 40g, and 100g widely available, and 400g promised in just a few short years. What isn’t so obvious is how these higher speeds are being reached. A 100g link, for instance, is really four 25g links bundled as a single link at the physical layer. If the optics are increasing in speed, and the processors are increasing in their ability to switch traffic, why are these higher speed links being built in this way? According to the paper under investigation today, the reason is the speed of the chips that serialize traffic from and deserialize traffic off the optical medium. The development of the Complementary metal–oxide–semiconductor, of CMOS, chips required to build ever faster optical interfaces seems to have stalled out at around 25g, which means faster speeds must be achieved by bundling multiple lower speed links.

Mellette, William M., Alex C. Snoeren, and George Porter. “P-FatTree: A Multi-Channel Datacenter Network Topology.” In Proceedings of the 15th ACM Workshop on Hot Topics in Networks, 78–84. HotNets ’16. New York, NY, USA: ACM, 2016. https://doi.org/10.1145/3005745.3005746.

The authors then point out that many data operators Continue reading

Worth Reading: Moving the Data Center to Base-8

The MTP (MPO-style) connector, launched in 1996, revolutionizes the design and deployment of cabling in the data center. Having 12 fibers in a single ferrule, it made dramatic progress in meeting the high-level challenges of speed, density and ease of installation. —Jennifer Cline And David Hessong @The Data Center Journal

Worth Reading: Always measure one level deeper

A good performance evaluation provides a deep understanding of a system’s behavior, quantifying not only the overall behavior but also its internal mechanisms and policies. It explains why a system behaves the way it does, what limits that behavior, and what problems must be addressed in order to improve the system. —John Ousterhout @CACM (requires subscription login)

Worth Reading: Iw4o6

The main issue with DS-Lite is the Network Address Translation (NAT) function that’s deployed at the carriers’ network. Since mapping between IPv4 and IPv6 addresses is per network-flow, DS-Lite is hard to scale. To solve this problem, lw4o6 proposes maintaining the per-subscriber state and moves the NAT function back to the customer premises equipment (CPE). —Diego Pino García @APNIC

Worth Reading: Water cooling making a comeback

Water cooling has come a long way since that time, and while air cooling of machinery has been a boon, allowing for simpler datacenters, in terms of thermal densities, we are getting back to the kind of heat buildup that forced water cooling on the datacenter to begin with. —Timothy Prickett Morgan @The Next Platform

Short Take: Culture and Technology

Worth Reading: A deep dive into STARTTLS everywhere

Unlike PGP and S/MIME, STARTTLS provides hop-to-hop encryption (TLS for email), not end-to-end. Without requiring configuration on the end-user’s part, a mailserver with STARTTLS support can protect email from passive network eavesdroppers. —Syndey Li @EFF

Worth Reading: How the Hippies Destroyed the Internet

Today’s Internet, with its techno-utopian culture,a connects with the 1960s counterculture movement. —Moshe Y. Vardi @CACM

Community Roundtable: MPLS Part 2

In this community roundtable over at the Network Collective, Jordan, Eyvonne, Nick, and I discuss some interesting use cases for MPLS. This is part of our ongoing series about protocols.

Remember to check out Network Collective memberships!

Worth Reading: Hyperledger

…there are a number of challenges to the widespread use of permissioned distributed ledger technologies (DLT). Key among them are problems associated with the lack of standards, the regulatory challenges and the lack of knowledge about DLT. @OpenSource

Weekend Reads 062918

The Internet and related digital systems that the United States did so much to create have effectuated and symbolized US military, economic, and cultural power for decades. The question raised by this essay is whether these systems, like the Roman Empire’s roads, will come to be seen as a platform that accelerated US decline. @The Hoover Institute

Article 13 reverses one of the key legal doctrines that allowed the Internet to thrive: the idea that computer networks are not “publishers” and are therefore not liable for the actions or statements of their users. This means that you can sue an individual user for libel or copyright infringement, but not the e-mail service or bulletin board or social media platform on which he did it. This immunity made it possible for computer networks to open a floodgate of content produced by independent individuals, without requiring service providers to serve as editors or moderators. —Robert Tracinski @The Federalist

The U.S. Supreme Court today ruled that the government needs to obtain a court-ordered warrant to gather location data on mobile device users. The decision is a major development for privacy rights, but experts say it may have limited bearing on the selling Continue reading

Looking Up

Worth Reading: The value of IT Analytics

Information technology operations analytics (ITOA) has emerged as a valuable practice that enables tech managers to increase efficiency. It uses data-science principles to perform pattern discovery, correlation, anomaly detection and root-cause analysis against data collected from underlying infrastructure and applications. —David Ishmael @The Data Center Journal

Worth Reading: A successor to OpenFlow?

Using OpenFlow, SDN was supposed to deliver a programmable interface to the network, thereby enabling real-time network control and innovation. In reality, it achieved only a fraction of what was promised. —Hayim Porat @ECI

Worth Reading: The power of hyperscale

The growth of cloud-IT adoption continues unabated. Today’s landscape of cloud providers is dominated by a small handful of companies based in the U.S. and China that deploy company-owned hyperscale data centers. For the foreseeable future, these few will account for much of the growth in the cloud-IT market as many businesses decide to give up owning their own data centers and move their applications to cloud platforms. —Marc Cram @The Data Center Journal

Chatting with Rachel Traylor about Math at CHINOG

Chatting with Eman Conde at CHINOG about Certifications

Worth Reading: A closer look at the IP Header

The IP identification field of the IP header (IP-ID) was introduced with RFC 791 in the early ’80s, to assist network-layer fragmentation and reassembly processes. —Flavia Salutari @APNIC

Worth Reading: Vulnerabilities are Guaranteed

The long years of experience have taught me through experience, hardware & software vulnerabilities are guaranteed. It is not a matter of “if” but when. —Barry Green

On the ‘web: Considerations in Network Complexity

One of my articles was published in the most recent Internet Protocol Journal:

Computer networks are complex—and getting more complex by the day. At one time, knowing the Internet Protocol (IP) was enough; today there are underlays, overlays, virtualized services, service chains, and a host of other technologies engineers need to plan around and for. With complexity on the rise, maybe it’s time to ask some fundamental questions, such as—what does complexity mean? Can complexity be solved? How can engineers manage complexity? @The Internet Protocol Journal

If you don’t subscribe to or read IPJ, you should—it’s a great source of information written by industry leaders and thinkers.