Deconstructing SoftLayer's Three-Tiered Network

July 24, 2013

When Sun Microsystems VP John Gage coined the phrase, "The network is the computer," the idea was more wishful thinking than it was profound. At the time, personal computers were just starting to show up in homes around the country, and most users were getting used to the notion that "The computer is the computer." In the '80s, the only people talking about networks were the ones selling network-related gear, and the idea of "the network" was a little nebulous and vaguely understood. Fast-forward a few decades, and Gage's assertion has proven to be prophetic ... and it happens to explain one of SoftLayer's biggest differentiators.

SoftLayer's hosting platform features an innovative, three-tier network architecture: Every server in a SoftLayer data center is physically connected to public, private and out-of-band management networks. This "network within a network" topology provides customers the ability to build out and manage their own global infrastructure without overly complex configurations or significant costs, but the benefits of this setup are often overlooked. To best understand why this network architecture is such a game-changer, let's examine each of the network layers individually.

SoftLayer Private Network

Public Network

When someone visits your website, they are accessing content from your server over the public network. This network connection is standard issue from every hosting provider since your content needs to be accessed by your users. When SoftLayer was founded in 2005, we were the first hosting provider to provide multiple network connections by default. At the time, some of our competitors offered one-off private network connections between servers in a rack or a single data center phase, but those competitors built their legacy infrastructures with an all-purpose public network connection. SoftLayer offers public network connection speeds up to 10Gbps, and every bare metal server you order from us includes free inbound bandwidth and 5TB of outbound bandwidth on the public network.

Private Network

When you want to move data from one server to another in any of SoftLayer's data centers, you can do so quickly and easily over the private network. Bandwidth between servers on the private network is unmetered and free, so you don't incur any costs when you transfer files from one server to another. Having a dedicated private network allows you to move content between servers and facilities without fighting against or getting in the way of the users accessing your server over the public network.

It should come as no surprise to learn that all private network traffic stays on SoftLayer's network exclusively when it travels between our facilities. The blue lines in this image show how the private network connects all of our data centers and points of presence:

SoftLayer Private Network

To fully replicate the functionality provided by the SoftLayer private network, competitors with legacy single-network architecture would have to essentially double their networking gear installation and establish safeguards to guarantee that customers can only access information from their own servers via the private network. Because that process is pretty daunting (and expensive), many of our competitors have opted for "virtual" segmentation that logically links servers to each other. The traffic between servers in those "virtual" private networks still travels over the public network, so they usually charge you for "private network" bandwidth at the public bandwidth rate.

Out-of-Band Management Network

When it comes to managing your server, you want an unencumbered network connection that will give you direct, secure access when you need it. Splitting out the public and private networks into distinct physical layers provides significant flexibility when it comes to delivering content where it needs to go, but we saw a need for one more unique network layer. If your server is targeted for a denial of service attack or a particular ISP fails to route traffic to your server correctly, you're effectively locked out of your server if you don't have another way to access it. Our management-specific network layer uses bandwidth providers that aren't included in our public/private bandwidth mix, so you're taking a different route to your server, and you're accessing the server through a dedicated port.

If you've seen pictures or video from a SoftLayer data center (or if you've competed in the Server Challenge), you probably noticed the three different colors of Ethernet cables connected at the back of every server rack, and each of those colors carries one of these types of network traffic exclusively. The pink/red cables carry public network traffic, the blue cables carry private network traffic, and the green cables carry out-of-band management network traffic. All thirteen of our data centers have the same colored cables in the same configuration doing the same jobs, so we're able to train our operations staff consistently between all thirteen of our data centers. That consistency enables us to provide quicker service when you need it, and it lessens the chance of human error on the data center floor.

The most powerful server on the market can be sidelined by a poorly designed, inefficient network. If "the network is the computer," the network should be a primary concern when you select your next hosting provider.

-@khazard

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