Recently in Internet Category

The Geopolitics of Iranian Connectivity

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As Iran celebrates the anniversary of the 1979 Islamic Revolution, it seems like an opportune time to look in on the evolving state of their Internet connectivity. When we last looked, after the disputed elections in June 2009, the picture was one of uneasy stability: logically diverse but physically constrained transit via the United Arab Emirates, backup transit via Turkey. Today, a third way out of the bottle is visible in the routing table: substantial amounts of Internet transit have materialized through a Russian provider. And there, in those obscure entries in the global Internet routing table, may lie echoes of Iran's larger geopolitical strategy.

Remember when the telephone company came to your house to hook up your phone and gave you a new phone number? This new number was how your friends and family were going to contact you. You counted on the telephone company to ensure that someone hadn't already been issued that number, because if they had, various problems would ensue. What would happen when your mom tried to call your number if it was also assigned to someone else? Could you directly call the other party to work out the problem? Well, in the BGP realm, something similar has been happening with autonomous system numbers (ASNs).

Organizations need an ASN to run BGP and route on the Internet. They are each assigned globally unique ASN(s) by their local Regional Internet Registry (RIR), who get them from IANA. A few weeks ago, the NANOG folks noticed that AS1712 had been registered by two different organizations (in France and Texas) that were both using the number to announce their separate network prefixes. ARIN issued a statement conveying that they were aware of the problem and were working to resolve it. We took a look at the data and found that AS1712 isn't the only dually-assigned ASN out there. In fact, even a root server didn't escape unscathed.

Lights Out in Rio

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When the power goes out to a large part of Brazil, as happened last night shortly after 10pm, it's going to have an impact on telecommunications.

Staring Into The Gorge: Router Exploits

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gorge.jpgI'm writing this blog entry from the campground at Vermont's beautiful Quechee Gorge, where I took the kids after work. Yes, Renesys is located smack in the middle of some of the nicest hiking, camping, and climbing on earth. No, you shouldn't move here, Northern New England has enough out-of-staters already, thanks. Unless, that is, you are an unusually talented web developer, have worked as a peering coordinator, or know the Internet transit industry inside-out, in which case you should send me your CV, posthaste. thanks, --jim





Here We Go Again.

Imagine an innocent BGP message, sent from a random small network service provider's border router somewhere in the world. It contains a payload that is unusual, but strictly speaking, conformant to protocol. Most of the routers in the world, when faced with such a message, pass it along. But a few have a bug that makes them drop sessions abruptly and reopen them, flooding their neighbors with full-table session resets every time they hear the offending message. The miracle of global BGP ensures that every vulnerable router on earth gets a peek at the offending message in under 30 seconds. The global routing infrastructure rings like a bell, as BGP update rates spike by orders of magnitude in the blink of an eye. Links congest. Small routing hardware falls over and dies. It takes hours for things to return to normal.

Internet connectivity is a good thing. Many of us depend on it for everything from our livelihoods to our entertainment. However, the Internet is very fragile and even the The New York Times is worried about it. But they're primarily concerned with overloads that can occur when everyone on the planet does the same thing at roughly the same time, such as surfing for news about Michael Jackson. Unfortunately, we will never avoid all such scenarios. Physical systems are designed around average and typical peak loads, not around extremely high loads associated with very unlikely events. Who would pay for that?

And this applies to other complex systems besides the Internet. I was in India during 9/11 and, for two days, I could not make a traditional phone call to the US. Why? Everyone in India knows someone in NYC, and they all picked up the phone at the same time to check in on them. The circuits were so overloaded, I couldn't even get the friendly "Your call cannot be completed as dialed" message.

No system is ever going to be engineered for insanely high loads. If everyone in your town decides to take a shortcut through your neighborhood to avoid an accident on the highway, you are going to have trouble getting out of your driveway. But rather than give up and wait it out, there is something you can do in advance and at reasonable cost: build a second driveway to a different street on the other side of your house, one that isn't fed by the same access roads from the highway. This blog is about building such redundancy into your Internet connectivity, so you aren't disconnected by a single failure. And while it's good that the New York Times and various governments are watching the problem, if your business depends on the Internet, you're largely on your own to audit and verify that you are buying a sufficient level of redundancy for your budget. A lot of fragility problems could be solved by more informed consumers performing the necessary due diligence.

The Proxy Fight for Iranian Democracy

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If you put 65 million people in a locked room, they're going to find all the exits pretty quickly, and maybe make a few of their own. In the case of Iran's crippled-but-still-connected Internet, that means finding a continuous supply of proxy servers that allow continued access to unfiltered international web content like Twitter, Gmail, and the BBC.

Iran and the Internet: Uneasy Standoff

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We've received enough interest about our previous notes on Iranian Internet connectivity that I wanted to give a brief update, and some reflections.

Strange Changes in Iranian Transit

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Many media sources have reported outages in Iranian mobile networks and Internet services in the wake of Friday's controversial elections. We took a look at the state of Iranian Internet transit, as seen in the aggregated global routing tables, and found that the story is not as clear-cut as has been reported.

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Our weblog is written by a variety of Renesys employees. They run the gamut from senior execs and engineers to sales guys. Anyone who has something to say that could be informative or of interest to our customers and visitors, says it here.

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This page is an archive of recent entries in the Internet category.

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