Category Archives for "Russ White"

CLKscrew: Another side channel you didn’t know about

Network engineers focus on protocols and software, but somehow all of this work must connect to the hardware on which packets are switched, and data is processed. A big part of the physical side of what networks “do” is power—how it is used, and how it is managed. The availability of power is one of the points driving centralization; power is not universally available at a single price. If cloud is cheaper, it’s probably not because of the infrastructure, but rather because of the power and real estate costs.

A second factor in processing is the amount of heat produced in processing. Data center designers expend a lot of energy in dealing with heat problems. Heat production is directly related to power usage; each increase in power consumption for processing shows up as heat somewhere—heat which must be removed from the equipment and the environment.

It is important, therefore, to optimize power usage. To do this, many processors today have power management interfaces allowing software to control the speed at which a processor runs. For instance, Kevin Myers (who blogs here) posted a recent experiment with pings running while a laptop is plugged in and on battery—

Reply from 2607:f498:4109::867:5309:  Continue reading

Reaction: Centralization Wins

Warning: in this post, I am going to cross a little into philosophy, governance, and other odd subjects. Here there be dragons. Let me begin by setting the stage:

Decentralized systems will continue to lose to centralized systems until there’s a driver requiring decentralization to deliver a clearly superior consumer experience. Unfortunately, that may not happen for quite some time. —Todd Hoff @High Scalability

And the very helpful diagram which accompanies the quote—

The point Todd Hoff, the author makes, is that five years ago he believed the decentralized model would win, in terms of the way the Internet is structured. However, today he doesn’t believe this; centralization is winning. Two points worth considering before jumping into a more general discussion.

First, the decentralized model is almost always the most efficient in almost every respect. It is the model with the lowest signal-to-noise ratio, and the model with the highest gain. The simplest way to explain this is to note the primary costs in a network is the cost of connectivity, and the primary gain is the amount of support connections provide. The distributed model offers the best balance of these two.

Second, what we are generally talking about here Continue reading

Research: Facebook’s Edge Fabric

The Internet has changed dramatically over the last ten years; more than 70% of the traffic over the Internet is now served by ten Autonomous Systems (AS’), causing the physical topology of the Internet to be reshaped into more of a hub-and-spoke design, rather than the more familiar scale-free design (I discussed this in a post over at CircleID in the recent past, and others have discussed this as well). While this reshaping might be seen as a success in delivering video content to most Internet users by shortening the delivery route between the server and the user, the authors of the paper in review today argue this is not enough.

Brandon Schlinker, Hyojeong Kim, Timothy Cui, Ethan Katz-Bassett, Harsha V. Madhyastha, Italo Cunha, James Quinn, Saif Hasan, Petr Lapukhov, and Hongyi Zeng. 2017. Engineering Egress with Edge Fabric: Steering Oceans of Content to the World. In Proceedings of the Conference of the ACM Special Interest Group on Data Communication (SIGCOMM ’17). ACM, New York, NY, USA, 418-431. DOI:

Why is this not enough? The authors point to two problems in the routing protocol tying the Internet together: BGP. First, they state that BGP is not Continue reading