Welcome!

Containers Expo Blog Authors: Yeshim Deniz, Pat Romanski, Elizabeth White, Liz McMillan, Ravi Rajamiyer

Related Topics: SDN Journal, Containers Expo Blog, @CloudExpo

SDN Journal: Blog Feed Post

SDN: Network Scalability’s Secret Sauce By @LMacVittie | @CloudExpo #SDN #Cloud

Scaling things seems like such a simple task, doesn’t it?

Scaling things seems like such a simple task, doesn’t it? Open a new checkout line. Call a new teller to the front. Hire another person.

But under the covers in technology land, where networking standards rule the roost, it really isn’t as simple as just adding another “X”. Oh, we try to make it look that simple, but it’s not. Over the years we (as in the industry ‘we’) have come up with all sorts of interesting ways to scale systems and applications within the constraints that IP networking places upon us.

One of those constraints is that physical (L2) and logical (L3) addresses have a one-to-one mapping. Oh, I know it looks like packets are routed based on IP address but really, they aren’t. They’re routed based on physical (MAC) addresses. And every switch (and router) keeps track of that mapping. 10.1.1.1? That goes to physical device A. 10.1.1.2? That goes to physical device B.

apartment routing

That makes scalability a lot harder than you might think because horizontal scaling uses clusters of things, all with their own IP-MAC combination. After all, if a user makes a request to 10.0.0.1, it’s going to be mapped somewhere to a single, specific device. When you’re trying to distribute traffic across multiple devices (to scale) means somehow figuring out how to remap those associations. And while you could do that, it would totally destroy network performance and throughput.

Think of the router like a building. When it’s a house it probably has one name (logical) and one address (physical). It’s easy to route to it, we know where it is.

But if we’re trying to scale up housing, we might replace the house with an apartment building. Now we have one logical (names) going to the multiple physical (address). They can’t all share the same logical address. The post man can get to the right address, but can’t figure out how to find Bob to deliver the mail.

So we add a bellman (proxy, load balancer, ADC) to the equation and give him the logical and physical address. All the apartments get their own physical and logical address (like “Apt 3”) and we ask the bellman to deliver the mail to not only Bob but Alice and Mary and Frank, too.

We give the bellman a Virtual IP (VIP) address to represent the cluster of “things” (apartments). That’s how we mask the complexity of actually distributing load across multiple devices (servers, apps, instances). That user doesn’t talk directly to any app instance or server; it talks to the VIP, which in turn determines to which instance to forward the request.  Because we’re sitting in the middle, we can exploit the one-to-one mapping between the physical and the logical by presenting ourselves as the endpoint and then distribute requests and traffic across a cluster to achieve really high scale of all sorts of things. The IP-MAC association is preserved and there’s no need for tricks to get around it.

But (and you knew there was a but coming, didn’t you?) there are times when that one-to-one mapping thing gets in the way. After all, a VIP is still an IP, and it is constrained by the same one-to-one mapping requirement. So when you need to scale the VIP by adding more devices (cause your apartment building is really flourishing and one bellman just isn’t enough anymore), you run into the same problem as we just ran into when we tried to scale the app. To which node in the VIP cluster should traffic be routed? Who gets to hold the VIP address so the upstream router or switch knows where to send those packets? Turns out the solution is similar in nature, we have to go upstream to figure out how to fix it.

Except upstream is a standard switch or router that expects –nay, it demands – a one-to-one mapping between physical (L2) and logical (L3) addresses.

This is where SDN comes in handy and provides some secret (network) scalability sauce.

One of the neat things about OpenFlow-based SDN is its use of OpenFlow and in particular the use of match/action programmability. Rather than hard-coding routes in the configuration, OpenFlow-enabled devices are able to programmatically consult a flow table that allows it to match attributes – like source IP address – with an action, like forwarding to a specific port or changing the destination MAC (physical) address.

You see where I’m going with this, right?

By taking advantage of this capability we can use an upstream, OpenFlow-enabled SDN switch to change the destination MAC (physical) address based on matching attributes. That means that we can work around that pesky one-to-one mapping problem that might prevent us from scaling out the bellman (proxy). But that’s not all we need. Scalability today is one part technical and another part operational. We can’t maintain operational efficiency if we have to manually adjust flow tables whenever we add (or remove) a proxy based on demand. So we need some magic, and that magic is programmability.

Whenever the cluster changes (a proxy is added or removed) we need to be able to update the upstream (SDN) switch so it knows how to distribute traffic to the proxies. To do that, we use programmability to use the control-plane separation inherent in SDN and update the flow tables, keeping them accurate so traffic is directed appropriately automagically. So not only can we increase the size of the apartment building, but we can scale out the number of bellmen we need make sure mail is delivered to the right apartment at the right time.

It turns out that in large implementations – like those you might find in a service provider’s network – that this is a really handy thing to be able to do, especially as Network Functions Virtualization (NFV) takes hold and app services are increasingly delivered via virtual appliances. Scalability becomes critical by necessity; virtual appliances are increasing capacity at breakneck speed but still aren’t able to match their purpose-built hardware counterparts. Scale of “the network”, therefore, is key to keeping up with demand and keeping costs down. But to do that requires some magic, and that magic turns out to be SDN.

You can dig even deeper into just such a solution by taking a gander at my colleague Christian Koenning’s blog right here on DevCentral, or go straight to the source and check out the iApp/iRule solution we’ve developed to automagically handle this scenario.

Happy Scaling!

Read the original blog entry...

More Stories By Lori MacVittie

Lori MacVittie is responsible for education and evangelism of application services available across F5’s entire product suite. Her role includes authorship of technical materials and participation in a number of community-based forums and industry standards organizations, among other efforts. MacVittie has extensive programming experience as an application architect, as well as network and systems development and administration expertise. Prior to joining F5, MacVittie was an award-winning Senior Technology Editor at Network Computing Magazine, where she conducted product research and evaluation focused on integration with application and network architectures, and authored articles on a variety of topics aimed at IT professionals. Her most recent area of focus included SOA-related products and architectures. She holds a B.S. in Information and Computing Science from the University of Wisconsin at Green Bay, and an M.S. in Computer Science from Nova Southeastern University.

IoT & Smart Cities Stories
We are seeing a major migration of enterprises applications to the cloud. As cloud and business use of real time applications accelerate, legacy networks are no longer able to architecturally support cloud adoption and deliver the performance and security required by highly distributed enterprises. These outdated solutions have become more costly and complicated to implement, install, manage, and maintain.SD-WAN offers unlimited capabilities for accessing the benefits of the cloud and Internet. ...
Business professionals no longer wonder if they'll migrate to the cloud; it's now a matter of when. The cloud environment has proved to be a major force in transitioning to an agile business model that enables quick decisions and fast implementation that solidify customer relationships. And when the cloud is combined with the power of cognitive computing, it drives innovation and transformation that achieves astounding competitive advantage.
DXWorldEXPO LLC announced today that "IoT Now" was named media sponsor of CloudEXPO | DXWorldEXPO 2018 New York, which will take place on November 11-13, 2018 in New York City, NY. IoT Now explores the evolving opportunities and challenges facing CSPs, and it passes on some lessons learned from those who have taken the first steps in next-gen IoT services.
Founded in 2000, Chetu Inc. is a global provider of customized software development solutions and IT staff augmentation services for software technology providers. By providing clients with unparalleled niche technology expertise and industry experience, Chetu has become the premiere long-term, back-end software development partner for start-ups, SMBs, and Fortune 500 companies. Chetu is headquartered in Plantation, Florida, with thirteen offices throughout the U.S. and abroad.
DXWorldEXPO LLC announced today that ICC-USA, a computer systems integrator and server manufacturing company focused on developing products and product appliances, will exhibit at the 22nd International CloudEXPO | DXWorldEXPO. DXWordEXPO New York 2018, colocated with CloudEXPO New York 2018 will be held November 11-13, 2018, in New York City. ICC is a computer systems integrator and server manufacturing company focused on developing products and product appliances to meet a wide range of ...
SYS-CON Events announced today that DatacenterDynamics has been named “Media Sponsor” of SYS-CON's 18th International Cloud Expo, which will take place on June 7–9, 2016, at the Javits Center in New York City, NY. DatacenterDynamics is a brand of DCD Group, a global B2B media and publishing company that develops products to help senior professionals in the world's most ICT dependent organizations make risk-based infrastructure and capacity decisions.
René Bostic is the Technical VP of the IBM Cloud Unit in North America. Enjoying her career with IBM during the modern millennial technological era, she is an expert in cloud computing, DevOps and emerging cloud technologies such as Blockchain. Her strengths and core competencies include a proven record of accomplishments in consensus building at all levels to assess, plan, and implement enterprise and cloud computing solutions. René is a member of the Society of Women Engineers (SWE) and a m...
Nicolas Fierro is CEO of MIMIR Blockchain Solutions. He is a programmer, technologist, and operations dev who has worked with Ethereum and blockchain since 2014. His knowledge in blockchain dates to when he performed dev ops services to the Ethereum Foundation as one the privileged few developers to work with the original core team in Switzerland.
@DevOpsSummit at Cloud Expo, taking place November 12-13 in New York City, NY, is co-located with 22nd international CloudEXPO | first international DXWorldEXPO and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time t...
Headquartered in Plainsboro, NJ, Synametrics Technologies has provided IT professionals and computer systems developers since 1997. Based on the success of their initial product offerings (WinSQL and DeltaCopy), the company continues to create and hone innovative products that help its customers get more from their computer applications, databases and infrastructure. To date, over one million users around the world have chosen Synametrics solutions to help power their accelerated business or per...