Many devices also support running OpenFlow in a hybrid mode, meaning OpenFlow can be deployed on a given port, virtual local area network VLAN , or even within a normal packet-forwarding pipeline such that if there is not a match in the OpenFlow table, then the existing forwarding tables MAC, Routing, etc.
What this means is OpenFlow is a low-level protocol that is used to directly interface with the hardware tables e. OpenFlow is a low-level protocol that manipulates flow tables, thus directly impacting packet forwarding. OpenFlow was not intended to interact with management plane attributes like authentication or SNMP parameters. This is not unlike the granularity offered by Policy Based Routing. The advent of OpenFlow meant that we could now achieve the same granularity with traffic forwarding decisions, but in a vendor-neutral way.
There is a long history of technology and research that predates OpenFlow, although OpenFlow is the technology that started the SDN revolution. Why OpenFlow? Martin Casado had a job working for the national government while he was attending Stanford. During his time working for the government, there was a need to react to security attacks on the IT systems after all, this is the US government. Casado quickly realized that he was able to program and manipulate the computers and servers as he needed.
The actual use cases were never publicized, but it was this type of control over endpoints that made it possible to react, analyze, and potentially re- program a host or group of hosts when and if needed. After all, each network device was closed locked from installing third-party software, as an example and only had a command-line interface CLI. In reality, the way networks were managed had never changed in over 20 years except for the addition of CLI commands for new features.
From Telnet to SSH source: Big Switch Networks All joking aside, the management of networks has lagged behind other technologies quite drastically, and this is what Casado eventually set out to change over the next several years.
Other technologies almost always have more modern ways of managing a large number of devices for both configuration management and data gathering and analysis—for example, hypervisor managers, wireless controllers, IP PBXs, PowerShell, DevOps tools, and the list can go on. Some of these are tightly coupled from vendors as commercial software, but others are more loosely aligned to allow for multi-platform management, operations, and agility.
If we go back to the scenario while Casado was working for the government, was it possible to redirect traffic based on application? Did network devices have an API? The answers were largely no across the board. The initial OpenFlow spec was the result of Martin Casado experiencing these types of problems firsthand. While the hype around OpenFlow has died down since the industry is starting to finally focus more on use cases and solutions than low-level protocols, this initial work was the catalyst for the entire industry to do a rethink on how networks are built, managed, and operated.
Thank you, Martin. What Is Software Defined Networking? Are they the same thing, different things, or neither? Having reference examples and designs streamlines the understanding of what Cloud was and is, but even before these terms did exist, it could be debated that when you saw Cloud, you knew it.
Are they really SDN? Not really. OpenFlow Even though we introduced OpenFlow earlier, we want to highlight a few more key points you should be aware of related to OpenFlow. What has actually happened, though, is that vendors who use OpenFlow in their solution examples include Big Switch Networks, HP, and NEC have developed OpenFlow extensions due to the pace of standards and the need to provide unique value-added features that the off-the-shelf version of OpenFlow does not offer.
When OpenFlow is used, you do gain the benefit to getting more granular with how traffic traverses the network, but with great power comes great responsibility. This is great if you have a team of developers. For most other organizations, the use of OpenFlow or any other given protocol will be less important than what an overall solution offers to the business being supported.
OpenFlow is just the main protocol being used to accomplish this functionality. It refers to taking functions that have traditionally been deployed as hardware, and instead deploying them as software. These smaller devices become much more manageable from an individual device perspective. The preceding scenario uses virtual appliances as the form factor for NFV-enabled devices. This is merely an example. Modernize and optimize network management with APIs and automation Legacy network management approaches dont scale adequately and cant be automated well.
This guide will help meet tomorrows challenges by adopting network programmability based on Application Programming Interfaces APIs. Using these techniques, you can improve efficiency, reliability, and flexibility; simplify implementation of high-value technologies; automate routine administrative and security tasks; and deploy services far more rapidly.
Four expert authors help you transition from a legacy mindset to one based on solving problems with software. Share from cover. Share from page:. More magazines by this user. Close Flag as Inappropriate. You have already flagged this document. Thank you, for helping us keep this platform clean. The editors will have a look at it as soon as possible. Matt Oswalt.
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