Lifting the Fog Around the Stupid Network – iPlane
“Deliver the Bits, Stupid.”
- David Isenberg – Rise of the Stupid Network
Stupidity is a virtue – for networks.
But not all networks should be stupid – only the underlying IP network our applications are built on.
Case in point: the overlay networks implemented by today’s new breed of distributed applications are getting smarter and smarter – and this is a very good thing. But overlay networks have been severely limited by the fogginess of the stupid network.
The fog of the stupid network is unknown loss, unknown latency, unknown bandwidth. Packets get dropped into the ether and there only are a few strategies an application developer can turn to in dealing with issues of latency, loss or congestion. The common techniques revolve around passive mechanisms for dealing with network conditions as they occur. Jitter buffering and streaming media throttling fit this description. Good techniques – but not good enough.
The solution to this problem is not to get rid of the stupid network, but to map it. Lift the fog.
That’s what the Systems and Networking team at UW has done with iPlane. Instead of making guesses with path-local information (think ping, traceroute) about properties of the network that are essentially non-local, applications can make direct use of a global view of these properties.
iPlane consists of two pieces:
- A set of mechanisms for collecting network connectivity and path information and supplementing the resulting map with hints that implies routing (location, topology, and other details)
- A simple query interface to the resulting map database
The iPlane team was kind enough to provide me with access to an early version of the query interface – it’s rough around the edges but has huge potential for improving the performance of today’s most interesting new applications (Joost comes to mind).
iPlane is a leap ahead of the baby steps made so far towards active techniques for dealing with poor network conditions. Skype attempts to route voice traffic through relay peers – but as any Skype user knows the resulting call quality can still run the whole range from very good to very bad. Many P2P networks preferentially remain connected to faster hosts while disconnecting from under-performers – but this behavior, while able to improve download speeds, is based on simple heuristics and “converges” towards more optimal sets of download hosts fairly slowly. iPlane will enable application overlay networks to go far beyond these techniques.
Check out the excellent talk on iPlane by Tom Anderson on Google TechTalks.
Jeff
