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FierceTelecom.com 10 9 M ay 2 0 13 M ay 2 0 13 FierceTelecom something like GMPLS outside the data center for control, but GMPLS doesn't talk to the SDN controller," he said. "At the same time, SDN is not going to replace GMPLS because there is just too much maturity there. SDN is more likely to be an overlay that fits with what GMPLS provides. Going back to the Ethernet example, carriers shunned that technology for many years before accepting it. SDN may face no such discrimination, as carriers in many cases may be under pressure from the likes of Google and alternative cloud service providers to adopt more efficient and flexible service provisioning processes. Google was the first company to demonstrate SDN applied on a WAN basis, though some vendors who serve traditional carriers scoff at the suggestion that Google's project was a realistic representation of SDN at a WAN-size scale, since carriers like AT&T have many more nodes and much more complex network environments than Google. Still, carriers such as NTT, AT&T, Telefonica, Verizon, CenturyLink and others are confident enough in the potential benefits of transport SDN that they are already traveling the path toward adoption. "Traditional carriers right now are slow-rolling transport SDN," said Adva's Theodoras. "The No. 1 rule they follow with adopting anything new is not to break the network in the process. It will be a gradual transition for them." Transport SDN is beginning to make its way into networks, but is largely still in the pilot stage. Late last year, Infinera worked with the federal government's Energy Science's Network on a testbed that essentially was a proof-of- concept for the OTS, and how SDN could leverage the existing control functionality of GMPLS. Meanwhile, Adva in late April announced it was involved in a testbed at Marist College with IBM in which three simulated data centers were connected over the optical network by a common SDN controller. These projects and other are setting the stage of transport SDN to be an active area in the next year or so. "We're still in the early days of transport SDN," Infinera's Capuano said. "There is still a lot to be figured out." l components, like ASICs, dedicated to packet forwarding. They will typically run software developed by the original equipment manufacturer (OEM) for their proprietary hardware platform. Virtual switches are based on industry-standard, high-volume volume servers, and the software runs in either a virtual machine (VM) or a hypervisor on a standard server. One software option is to deploy Open vSwitch* (OVS), a production quality, multilayer virtual switch licensed under the open source Apache 2.0 license and now part of the Linux* kernel. Multiple vendors are supplying SDN controller software, all of which support OpenFlow*, one of the first standard communications interfaces defined between the control and forwarding layers (i.e., switch in the node layer) of an SDN architecture. 1 SwitCh Co-ExiStENCE Both physical and virtual switches have a place in SDN architecture. Figure 1 illustrates a hybrid SDN network that combines ToR switches (with and without OpenFlow) and virtual switches based on Open vSwitch. The ability to mix and match switch types provides investment protection for network operators. See Figure here. SwitCh CompAriSoN Why would network operators deploy both physical and virtual switches? Physical switches generally deliver faster packet forwarding throughput than virtual switches; but on the other hand, they do not scale as well or as easily. For instance, virtual switches can support a larger number of tunnels and flows (in excess of one million), they can be deployed on any general-purpose server in the network, and their capacity can be easily increased by adding more VMs. iNtEL ® rEFErENCE DESiGNS For phYSiCAL AND VirtUAL SwitCh DESiGNS Equipment manufacturers will be able to take advantage of two Intel reference designs to develop physical and virtual switches for deployment in the SDN node layer, called respectively: • Intel ® Open Network Platform Switch Reference Design (Intel ® ONP Switch Reference Design) (Available now) • Intel ® Open Network Platform Server Reference Design (Intel ® ONP Server Reference Design) (Availability target: 3Q13) Both of these designs support Open Networking Software (ONS), which includes OpenFlow and a rich API designed to provide a variety of Layer 1, Layer 2 and Layer 3 features. l Software-Defined Networking (SDN) was the buzz at the Mobile World Congress 2013, with many predicting an imminent revolutionary transformation in network architecture. However, a critical factor in convincing network operators to get onboard is to ensure there's a bridge to legacy systems, thus protecting their prior investments. For example, the industry needs interoperability between today's purpose-built, physical switches and tomorrow's software-based, virtual switches running on high-volume servers. Working to make this a reality, industry leaders and special interest groups (SIGs) are developing solutions that allow both types of switches to co-exist. thE SDN NoDE LAYEr SDN architecture consists of four layers, called orchestration, network applications, network controller and node. The SDN node layer performs the data plane (i.e., forwarding) functions of the network using computing devices that have been abstracted for applications and network services, allowing them to treat the network as a logical or virtual entity.1 This layer supports both physical and virtual switches, thereby addressing existing and emerging switch types. phYSiCAL AND VirtUAL SwitChES Physical switches, such as top-of- rack (ToR) switches, are usually built with application-specific silicon The Co-existence of Physical and Virtual switches in sDn sponsored Content 1 Source: "Software-Defined Networking: The New Norm for Networks," ONF White Paper, April 13, 2012, pg. 7, 11, 8, https://www.opennetworking. org/images/stories/downloads/white-papers/wp-sdn-newnorm.pdf. 2 Source: http://www.bigswitch.com/products/big-virtual-switch-network-virtualization. We're still in the early days of transport sDn. There is still a lot to be figured out." mike capuano, vice presiDent of corporate marketing at infinera

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