Extending the cloud to places that lack conventional connectivity is a problem. Think of an Azure Stack server in an oil rig or on a cruise liner, for example, or in a set of hard cases the back of a truck as part of a disaster relief response. Things get even more complicated when you consider edge processing systems, like Azure Databox Edge, where local processing pushes large data sets up to cloud systems for deeper analysis.
The demand for bandwidth isn’t going away — in fact, it’s only going to intensify. But the infrastructure isn’t available to put high-bandwidth fibre into rural locations, and laying all the necessary connections is economically prohibitive. It’s impossible to rely on universal service provisions for more than 1 or 2Mbps of ADSL over low-quality phone lines. While white spaces and other wireless technologies show promise, they’re only ways of getting data to the edge, not from the edge to the cloud.
Internet from the sky
The answer to the connectivity problem is an old one: satellite connectivity. Using a small base station, data can be transmitted via satellite to a public internet connection at a larger ground station facility. There’s no need to string miles of copper or fibre, and the base station can be either a permanent fixture or a portable device.
The public internet is not the best place for private data, and Azure has offered private connectivity through its ExpressRoute service for some time now. Using MLPS connectivity over leased fibre, it’s a fast way of turning Azure into an extension of your data centre. With ExpressRoute, each end of the connection is part of the same VNet, allowing you to connect local services directly to Azure.
Connecting to Azure via satellite
The network architecture of the new satellite extension to ExpressRoute is relatively simple. Instead of dropping an MLPS fiber connection into your data centre, Microsoft now terminates the fibre in the ground stations of selected satellite communications companies. Your data is transmitted over a standard satellite data connection from your site to the ground station, and then on to your selected Azure instances.
As all the satellite networking providers Microsoft works with use geostationary satellites, in most cases your data will be routed through a single ground station. However, if you’re using ExpressRoute from a mobile platform, say a ship, your data may well be routed through multiple ground stations. That shouldn’t be a problem; with the reach of Microsoft’s physical network your VNet can cover multiple endpoints.
It’s not the speed, it’s the latency that matters
The biggest issue facing any satellite internet connection is latency, with geostationary satellites adding approximately 500ms of latency to every packet transmission. It’s the equivalent of adding 46,000 miles of fibre to a connection, almost wrapping the equator twice! There are additional issues that you don’t get from fibre connections: you can expect to have a higher packet loss as available transmit power both from the ground and from the satellite can be low, and atmospheric conditions (especially rain and fog) can affect the overall available bandwidth as they interfere with microwave signals.
There are additional issues with mobile satellite terminals: it can be hard to get a lock on a satellite from a portable ground station or from an unstable platform like a ship or an aircraft, for example. In practice, a new generation of antennas reduces associated risks, but it’s important to realise that working with satellite connections is nothing like provisioning fibre in your data centre.
While that can be a problem for home and consumer connections, or anywhere real-time connectivity is required, for most industrial and commercial usage it’s much less of a problem as typical workloads involve streaming data to cloud applications for analysis, or for off-site backup. Treating a satellite ExpressRoute connection as a batch processing connection or a way of delivering events to a message queue makes a lot of sense, fitting well with expected usage patterns.
Connections to other Microsoft services
Users at a remote site can use ExpressRoute to connect to Microsoft services like Office 365, giving access to email and file shares. There’s even a secure option for Azure Government Cloud users, ensuring compliance with legal requirements for government services. Again, here latency is not a significant problem, as long as users are aware of slower saves and longer email send times. In addition, Microsoft states that its latency will be predictable as it reduces your exposure to the public internet.
SEE: Microsoft Azure: An insider’s guide (free PDF) (TechRepublic)
Satellite ExpressRoute connections aren’t limited to geostationary satellites, although you’re likely to find them the cheapest and easiest option for now. One provider offers support for medium earth orbit satellites, which can provide coverage in areas where geostationary coverage is poor, and Microsoft is planning to work with future constellations of low earth orbit smallsats. That last option is an interesting one, as planned networks like SpaceX’s Starlink will have many thousands of satellites offering inter-satellite switching via laser signaling. These future networks will have much lower latency, and thanks to their satellite-to-satellite connections may may even rival the performance of ground-based fibre networks.
Microsoft’s addition of satellite connectivity to its ExpressRoute portfolio is a recognition of the importance of the edge-to-cloud applications. We’ve seen it dramatically reducing the size of its edge-focused hardware from the multi-rack data centre-based Azure Stack to newer, rugged, half-rack-sized portable Azure Stack instances, and to single-server Azure Databox Edge hardware. Once hardware gets small enough and cheap enough, it’s going to be installed anywhere there’s space and anywhere you need that compute power. Providing connectivity to those devices, wherever they may be, is only the next step on Microsoft’s ubiquitous computing journey.
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