Original URL: https://www.theregister.co.uk/2013/10/24/datacentre_software_defined_networking/

Tracing the direction of data centre travel

Traffic management

By Trevor Pott

Posted in Networks, 24th October 2013 13:17 GMT

Interview The data centre has been evolving constantly but for almost 15 years networking has not. But even networking will have to adapt to the times eventually, so The Register sat down with Brocade's Julian Starr to understand where we are and where we are going.

Starr's first statement after the inititial pleasantries was: "What you care about is that the data flows, not how."

This serves as an excellent summation of Brocade's views.

Feel the fabric

My last major look at the future of networking was discussing OpenFlow with Renato Recio from IBM. Starr's statement sounded like something from within OpenFlow's remit, so I started there.

Starr's response was passionate: he is obviously a strong believer in OpenFlow and related software defined networking (SDN) technologies.

Starr is a quite a fan of networking fabrics. He sees traditional networks as full of problems. They do not handle a lost link or too much congestion well.

“What we should see is what we see in the storage world today: that you can track your recovery time in real time,” he says.

“Remove spanning tree and move towards a fabric-style platform and a lot of things start to go away. As you move to Trill, OpenFlow and proper SDN, there is a simplification of the platform

Starr views OpenFlow in terms of programmability, monitoring and transparency. Programmability is evident in that OpenFlow is basically "a big brain that tells you how your network should be”.

He talks about the programmability of Brocade's switches. "If you automate you can orchestrate; the goal of RESTful APIs is to do that, to have a set of common APIs that can be managed as part of a common infrastructure,” he says.

Monitoring and transparency are critical as "nobody is going to be able to determine the impacts of failure and resilience if you can't see where traffic is flowing”.

This has a direct impact on business analysis capabilities, an area Starr views as increasingly important.

Quick response

Transparency and monitoring feed back into the programmability aspect of OpenFlow in the form of automation. Networks should be responsive to changes, not just in the physical architecture (such as new links being added or servers disconnected) but to traffic flows.

Our data centres are increasingly virtualised. Network traffic becomes dynamic in a way that didn't exist before. Workloads talk among themselves without presenting that information to end-users, constantly moving from one physical host to another, changing the servers they communicate with as the day moves on.

According to Starr this has real-world impacts on how the software behind the software-defined data centre is crafted.

"Some of those models and decision-making structures become hard to code. We are going to see a sort of resurgence of management tools," he says.

Go with the flows

In a virtualised environment, we have generalised the hardware and wrapped up the operating system, applications and so forth into a neat little container. We move this back and forth and it is easy to conceptualise.

Network flows can be envisioned in much the same way. Instead of looking at network traffic as a stream of packets with QoS, filters, layer 2 routing, layer 3 routing and so forth, we start to look at it as communication between one system and another, abstracting the messy details of how.

“The goal of virtualisation is to make everything look the same,” says Starr.

We don't care how the data gets there, only that it does get there

This is not too dissimilar from what SDN is trying to achieve in the network space. Ultimately, Starr believes that network flows will move like virtual machines.

We don't care how the data gets there – what QoS is required, what filters it passes through, what switches or routers it visits along the way – only that it does get there and at the speeds we specified.

Analysis of network flows can help with other aspects of the data centre as well. "We have a resource broker that looks at the hypervisor, looks at the transaction load going to the server and measure response time in real time,” says Starr.

Look at those response times and model them. If peaks occur you can spot them, ramp up additional virtual machines, plug into the application controller, spread out the load, bring the response time down and then spin things back down when the load drops.

“You can really optimise the infrastructure. We can do that today, but there are always things we can do to help drive that forwards.," says Starr.

Ready to roll

All that sounds great but how many companies are ready to take advantage of that automation? Brocade views reaching the SDN ideal as an incremental process.

“If you have to buy a TV tomorrow, you don't buy one that is not HD ready. I think of it in terms of maturity,” says Starr.

“The premise behind the maturity model is that every time you buy a new device you take a step to the right – fully dynamic, billable by the second and so on. One of the places that the maturity model is taking us is that people are less concerned about brand. It's a value add, a 'solution'.

"In the network world what matters is that a network is ready for this IP backplane. From rack to rack to row to row to DC to DC, these three-tier architectures that are 20 years old don't deliver what is required.

“That's why we need things that behave like a fabric. This IP backplane is about adding automation and interaction with the surrounding infrastructure, so that you build intelligence into the network."

It doesn't end there, according to Starr. "That doesn't have to be the whole gamut of SDN. You can also build in application awareness, awareness of what's connected to it,” he says.

“There are two mentalities. There are the 800lb gorillas who say 'you will build a network this way for this application’. Then there are others on the other end that build in discovery and look for what is attached.

"Nobody really builds application-ready infrastructure anymore. Having a network that you can configure quickly is part of that. It doesn't have to be a full SDN capability; there can be baby steps towards it."

A network that detects the workloads attached to it and automatically configures itself to suit? Sounds intriguing.

Worth the price

Building in extra features that you won't necessarily use seems likely to drive up the cost. Why would a business pay for something it is not using, no matter what the potential might be?

Starr maintains that “HD ready" pieces are important for moving the network forward. He wants to see support for overlay coming to more networks.

“When people start using SDN they are going to start using tunnels. One of the key points is the visibility of flows and the ability to do something about it,” he says.

"That visibility is important. Those kind of stepping stones are important. You might not necessarily go down that programmability route, that OpenFlow route, or use those features today, but you can get some value from your infrastructure and be ready for tomorrow."

In Starr's view it is all about choice. "It is about what you choose to do in the networking world and having a commonality of management, something that can be deployed very easily. For example, our load-balancing platform will be delivered as a virtual machine or as a hardware client,” he says.

“If you get it as a hardware client you can partition it. You can say 'I will build it and they will come’. You can build a large hardware model or start with virtual machines and grow as it goes."

Starr says Brocade has very much embraced the concept of SDN, whether it is hardware from a load-balancing and routing perspective or a hardware choice.

The middle way

Some customers will need a very large platform, some will want to deploy a single virtual machine to a customer. Those things "will meet in the middle because of things like Intel's DPDK.

Even with networking gear built to work with SDN, Starr sees room for price differentiation. "I think there are differences between standards,” he says.

“You can have an IP backplane and remove a lot of the historical constraints, but where you start to see differences between vendors is depth of queue – which has quite a large difference for certain types of traffic. No drop, buffer depth, queuing capabilities have an impact on performance and cost per port."

Starr thinks SDN has a lot in store not just for the enterprise or the cloud service provider but for the mid-market as well.

If Brocade can deliver on its vision, then he is probably right. Adaptable switches that work together in a fabric but can still do it old school if needed seem like a great way to bridge the gap between the old and the new.

The data centre keeps on evolving. ®