Jim Cowie

Author Archives: Jim Cowie

Someone Disconnects North Korea – Who?


North Korea went off the Internet Monday, 22 December 2014, at 16:15 UTC (01:15 UTC Tuesday in Pyongyang) after more than 24 hours of sustained weekend instability. Dyn continually measures the connectivity and performance of more than 510,000 individual networks worldwide, identifying impairments to Internet commerce. It’s a rare event these days when an entire country leaves the Internet (as Egypt did, or Syria). Even so, when North Korea’s four networks went dark, we were not entirely surprised, based on the fragility of their national connectivity to the global Internet.


Who caused this, and how? A long pattern of up-and-down connectivity, followed by a total outage, seems consistent with a fragile network under external attack. But it’s also consistent with more common causes, such as power problems. Point causes such as breaks in fiberoptic cables, or deliberate upstream provider disconnections, seem less likely because they don’t generate prolonged instability before a total failure. We can only guess. The data themselves don’t speak to motivations, or distinguish human factors from physical infrastructure problems.

As the sun rises in Pyongyang, the national Internet disconnection continues. An outage of this duration is not without precedent for North Korea. As we’ve written before, Continue reading

Renesys Team Launches Dyn Research


Welcome to the new Dyn Research Blog!   We’re certainly glad you’re here, and we hope you like the snazzy new look.

Since the Renesys team joined Dyn in May, the number one question we’ve received is “will you keep publishing the blog?”   The answer is yes, absolutely, and we hope to bring you some diverse perspectives on Internet performance from other members of the Dyn technical team as well.    Please do let us know what you think of the new Dyn Research Blog, and feel free to suggest topics you’d like us to cover.


A moment for reflection

Looking back over the eight years that we’ve been publishing our observations about Internet structure and operations, I’m struck mostly by how you, our audience, have evolved and grown.    In the early days, news about Internet infrastructure appealed to a pretty narrow group of readers within the network operations community.   We never had to buy beer at conferences like NANOG, but the rest of the world was more or less content to ignore the dirty details of IPv6, peering and depeering, Net Neutrality, and the evolution of the IP wholesale transit industry.

A Continue reading

Internet Touches Half Million Routes: Outages Possible Next Week

There was minor consternation in Internet engineering circles today, as the number of IPv4 networks worldwide briefly touched another magic “power of 2″ size limit. As it turns out, 512K (524,288 to be exact, or 2-to-the-19th power) is the maximum number of routes supported by the default TCAM configuration on certain aging hardware platforms.

The problem is real, and we still haven’t seen the full effects, because most of the Internet hasn’t yet experienced the conditions that could cause problems for underprovisioned equipment. Everyone on the Internet has a slightly different idea of how big the global routing table is, thanks to slightly different local business rules about peering and aggregation (the merging of very similar routes to close-by parts of the Internet address space). Everyone has a slightly different perspective, but the consensus estimate is indeed just under 512K, and marching higher with time.

The real test, when large providers commonly believe that the Internet contains 512K routes, and pass that along to all their customers as a consensus representation of Internet structure, will start later this week, and will be felt nearly everywhere by the end of next week.

Enterprises that rely on the Internet for delivery of Continue reading

Brazil’s Winning Internet

Another World Cup is in the books, and it’s fair to say that most people will remember 2014 for the inglorious and improbable performance of the host nation, losing 7-1 and 3-0 in its semifinal and consolation matches. Brazil’s sad exit capped off a year of soul-searching about the nation’s massive investment in hosting the World Cup (and the Olympics yet to come).

But Brazil shouldn’t lose sight of one important silver lining to their World Cup cloud: the startlingly vibrant development of the Brazilian Internet, and the critical role Brazil now plays in the Internet connectivity and ICT development of South America.

Preparations for the World Cup and the Olympics may have helped light a fire under Brazil’s Internet infrastructure providers. Here’s a plot of the growth of the set of autonomous systems (that is, enterprises and service providers who originate IPv4 address space under their own registered Autonomous System Number) in Brazil over time. For comparison, we’ve also included the same statistic for South Africa. By this measure, the two World Cup host countries couldn’t be more different! brazil0

Brazil and South Africa invite comparison because of their many parallels: Continue reading

Renesys, Dyn Join Forces

Today, we’re announcing the acquisition of Renesys by Dyn, the leading provider of Internet Performance solutions. Dyn and Renesys represent the perfect combination of Internet Intelligence assets from Renesys and Traffic Management and Message Management solutions from Dyn. We’re excited to become part of the Dyn team!

Those who know both companies may ask, “What took you so long?” Our headquarters are located blocks apart in beautiful downtown Manchester, New Hampshire, and the two founding teams have known each other for years. Dyn and Renesys share a surprising amount of cultural DNA – building scalable global infrastructure, understanding the economics and performance of the Internet at a deep technical level, and helping our customers deliver smarter, faster service worldwide.

Why Renesys? Why Dyn?

Renesys builds network performance management products for the Internet. We help enterprises tackle the strategic and operational challenges of delivering service over the public Internet, to consumers and businesses beyond the firewall. We operate a best-in-breed global Internet measurement platform, performing over a billion measurements each day to assess the Internet’s health and function. Anywhere in the world, when a decision maker needs insight into local Internet infrastructure, performance impairment, economics, competition, or strategy, we Continue reading