We now live in an always-connected world, forcing networks to evolve in ways not anticipated even just a few short years ago. We asked Bishop & Associates’ Lisa Huff: What’s next in networking?
Programmability seems to be the latest network trend. Software-defined networks (SDN) and network functions virtualization (NFV), while hyped over the last five years, are starting to be reality. SDN is certainly being used in live networks inside the data center today, and NFV is being developed and standardized for telecom networks. How widespread these technologies will become remains to be seen, but both are here to stay. Let’s take a look at how they will be used.
Software-Defined Networking (SDN)
Software-defined networking (SDN) simply separates the network device control plane from its data-forwarding plane. This separation allows decoupling of the logical network services and capabilities from the underlying physical network. According to SSG-Now, “rather than having hard-coded software controlling proprietary hardware, SDN utilizes a software-based controller application to manage SDN-based network devices.”
So in a true SDN-based solution, instead of using Cisco’s or Juniper’s proprietary firmware, controllers, and operating systems, an open architecture SDN controller, like OpenFlow, would be used. Since the applications are now independent of the hardware, all network elements could be made flexible. For example, a virtual server deployment in an SDN-enabled application could bring up a firewall, set network line data rates, and change the configuration of the router, all without manual involvement. The Open Networking Foundation is currently standardizing SDN.
Open architecture SDN is still in its hype phase, but is now starting to be implemented in both telecom and data center networks. The Greenfield SDN solution is shown below.
Instead of the seven-layer OSI model, SDN simplifies it to three. Most current implementations of SDN, however, are hybrid, so they have some elements of SDN along with legacy networks. Currently, many SDN solutions remain proprietary. Several examples of products are summarized below:
Xsigo (now part of Oracle) released the first data center SDN product in 2009. Its I/O Director is a hardware and software device “that consolidates data center infrastructure and server I/O management.” It eliminates the server’s multiple Ethernet and Fibre Channel interfaces and uses a single high-speed Ethernet or InfiniBand link. Virtual Ethernet NICs and FC HBAs communicate over this link. A schematic of its solution is shown below.
While Oracle’s solution shows that it can be used in existing networks, there is also potential to eliminate existing routers and switches entirely. The implications of this are clear: First, FC HBA’s are eliminated from the servers in favor of an application-programming interface (API) that connects to the FC SAN, and then routing and switching functions can become APIs instead of hardware. Most network professionals do not think this will happen, mainly due to latency issues. Routers and switches can quickly move packets, while a “virtualized” router or switch may take as much as 10 times longer to do so. This is a non-starter in many network environments.
Mellanox’s products are based on SDN storage applications, which is why it has focused on both Ethernet and InfiniBand. Its implementation is shown below.
Vello Systems has a solution it says works for both the access/metro telecom network and inside the data center. Below is Vello’s example of what SDN can bring to the optical transport network.
This solution is targeted for the data center edge. In addition, Vello claims that it can be used to configure switches anywhere in a data center where there is a requirement for fine-grained bandwidth control. This unified Ethernet/DWDM solution uses OpenFlow and can provide end-to-end control within and across data centers. It can collapse the edge routers and LAN core routers into one network device. It is fully automated and programmable.
In February 2014, Vello deployed its solution in Pacnet’s network. According to a joint press release, Vello Systems’ innovative Connectivity Exchange software enables Pacnet Enabled Network (PEN) for enterprise and carrier customers to rapidly and cost-effectively create virtual, integrated, and intercontinental data centers. It has been installed in Australia, Hong Kong, Japan, Singapore, and the US.
SDN can offer an end-to-end programmable network. It can automate LAN/WAN provisioning across all applications. “An SDN-enabled data center network has the capability to monitor application states and change network resources and configurations on a continual basis, as needed,” according to SSG-NOW. The consequences of deploying SDN in the data center could entail eliminating some of the tried-and-true network elements, however. This could be why some of the large switch manufacturers are against widespread SDN installments.
Network Functions Virtualization (NFV)
There seems to be a bit of confusion in the industry about the difference between SDN and NFV. SDN was conceived in the campus network where researchers wanted to be able to test applications without having to manually update software on every network device. They developed a “programmable” network by separating control and forwarding functions, centralizing control, and using well-defined interfaces – APIs. This concept was then extended to the data center where server virtualization had already taken hold. Real implementations of SDN have started and are expected to become mainstream within the next year.
NFV was developed by communications service providers (CSPs) in order to accelerate the introduction of new services on their networks. The proprietary hardware elements that CSPs have used have made it cumbersome to quickly provision new services. The ultimate goal of NFV for the transport network is to consolidate network equipment types into standard servers, switches, and storage – to leverage simpler open network elements.
NFV is being standardized in the European Telecommunications Standards Institute (ETSI), while SDN is being standardized in the Open Networking Forum (ONF). These technologies will certainly work together to make an overall programmable network where SDN virtualizes the network and NFV virtualizes the appliances.
Large equipment manufacturers that have started to implement NFV include Brocade, Cisco, and Juniper. An example of Cisco’s Evolved Services Platform (ESP) is shown below.
Network consolidation and enhanced orchestration have been needed for many years, especially in telecom networks where it is very costly to turn up new services. Both SDN and NFV promise to help alleviate costly capital and operations expenditures and make the network flexible and programmable. Both AT&T and Verizon have embraced these technologies and are currently in trials to develop these next-generation networks.
Because SDN and NFV have the potential to drastically reduce the number of network elements, the volume of connectors and cables being used in networks could be drastically reduced. However, the network connections that remain will need to handle higher data rates, making them higher in value. In addition, as mentioned above, not all network engineers believe they can replace all routers and switches or even separate load-balancing equipment with SDN. This equipment is really efficient at what it does and they have not been persuaded that SDN will have the same efficiency. The bottom line is we will need to keep a close eye on how these technologies develop and how they will impact the number of ports, connectors, and cables used in next-generation networks.
- High-Speed Transmission Update: 200G/400G - July 18, 2016
- Ethernet Networking: The Proliferation of Data Rates - June 6, 2016
- The State of Data Center Networking Technologies - April 11, 2016