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Networking & Communications

The ongoing SDN race

Some of the larger vendors that were seen as slow in the SDN race--compared to some of the smaller firms--took the wraps off their offerings one after another in the past few months.

In August, Huawei launched its SDN-programmable S12700 Agile switch series, touting it as a next-generation product designed for managing campus networks.

The firm said its Agile switch is designed with its own Ethernet network processor that can handle different software tasks. It also claimed that the product will offer better performance over rival switches built with application-specific integrated circuit (ASIC) chips, but at a still affordable low price.

The big boys tackle SDN

In less than two months' time, both Juniper and Cisco also unveiled their SDN offerings. Juniper announced the availability of Juniper Networks Contrail, a network virtualization and intelligence SDN offering in mid-September. Contrail comprises all the components needed to create a virtual overlay network: SDN controller, vRouter, and analytics engine, the firm said.

Cyberport in Hong Kong, according to Juniper, is one of the organizations that evaluated Contrail. Cyberport CTO David Chung said the organization expects Contrail to provide seamless integration with its existing network.

Hard on the heels of Juniper, Cisco introduced the Cisco Network Convergence System (NCS) a week later. NCS is a network fabric family designed to serve as the foundation of a massively scalable, smarter and more adaptable Internet, said Cisco, adding that the system's programmability and virtualization capabilities enable service providers to accelerate the transition to SDN and network function virtualization.

SDN isn't new

Despite these vendors' recent push and the debate around the acronym in the past year, SDN isn't something new.

"The separation of the control plane [which makes decisions about where traffic is sent] and the forwarding plane [which forwards traffic to a selected destination] in SDN was developed more than 10 years ago, said Liu Shaowei, president, Huawei Enterprise Networking Product Line at Huawei Enterprise Networking Congress 2013 held in Shanghai early this year. "And that's only a small part of the SDN framework."

According to him, traditional networks are horizontally open and standardized while every network element can interconnect with neighboring nodes. But in the vertical direction, a network is closed and structureless, making it difficult to develop applications and deploy services vertically, he added.

"SDN helps realize vertical openness, standardization, and programmability on the entire network," said Liu. "This allows users to efficiently and conveniently access network resources."

SDN isn't OpenFlow

All these sound like OpenFlow. While SDN leverages OpenFlow capabilities, they aren't the same, said Douglas Murray, senior VP, Asia Pacific, Japan & Greater China, Juniper. "OpenFlow is a communications interface between the control and forwarding layers, while SDN is an architecture," he said.

According to the Open Networking Foundation (ONF), SDN as an architecture decouples the network control and forwarding functions, enabling the network control to become directly programmable and the underlying infrastructure to be abstracted for applications and network services.

The ONF is a user-driven organization dedicated to the promotion and adoption of SDN through open standards development.

According to Liu, SDN can help protect customer investment. "When the forwarding plane is programmable, organizations can customize their campus networks through software and application development rather than buying new hardware from vendors," he said.

As SDN encourages a transition from ASIC to programmability on the forwarding plane, networks and switches will become more agile in meeting changing traffic demand, he added.

When and where SDNs make sense

But SDN isn't for everybody, said US-based networking consultant and analyst Kurt Marko.

"It's unclear right now how valuable SDN will be to the typical enterprise datacenter," he said. "What's more clear is the technology's value for service providers and big cloud providers because their network traffic can be much more variable and unpredictable depending on what kinds of data are running over them, what types of applications are used and what types of end-user profiles they see," Marko pointed out.

"In an enterprise datacenter, however, the network traffic tends to be more uniform and stable. There's not so much of a high variability in the load, and they're already built to handle any big traffic spikes and react to those automatically," he said.

Where SDN has more potential in the enterprise is to replace network application hardware like load balancers, firewalls and other hardware that handles higher-level networking issues instead of individual packets of traffic, said Marko.

Five key considerations

In addition, organizations must assess themselves in deciding whether or not the benefits of SDN are worth their effort or investment. There are five considerations for IT shops evaluating SDNs, according to IT management software company SolarWinds:

1) The organization's access to personnel and capital resources

If an IT shop doesn't have network engineering expertise, or personnel is stretched thin, SDN is not the project to undertake, Castelino said.

SDN deployments are done in parallel with the production environment, test, evaluated, validated and tested again before they are cut over to the production network. It takes time, people and money.

2) The size of an organization's network

While there is not a distinct bare metal server or virtual machine threshold for implementing an SDN or not, the rule of thumb is hundreds of IP addresses. "For 50 IP addresses, it's not worth the change," he said. "For hundreds of IP addresses, you might need the automation."

3) The level of complexity of an organization's network

If there are requirements for a lot of network slicing or segmentation for security and isolation, you might be a good candidate for an SDN. If there are lots of virtual LANs to configure and manage, or there are VLANs that require more automation than others, SDNs might be a good fit.

4) The number of virtual machines within an organization's network

"If you're not at a few hundred, you're probably early," Castelino said. He reiterates that if an organization is running hundreds of workloads, it might be worth taking a look at SDNs. Below that level, and with SDN's immaturity, it might be "way too early" to look at.

5) The organization's need to simplify security measures and control access to applications

The benefit of SDN is that things get done the same way all the time, through policy, even though the environment is dynamic and always changing. Security and network access control in a dynamic environment can be a nightmare. It's important to get policy enforcement right in this regard not only to ease operation but to ensure information stays where it should.

Additional reporting by IDG News Service

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