SDN has made waves in the world of network management. With its cost-saving benefits, many network engineers are incorporating it into their network design plans.
Especially as network speeds continue to rise, it’s important to understand what SDN has to offer. Before you decide whether it’s right for your business or client, you must know how it could streamline your management and compare it to other options.
SDxCentral defines SDN as “a new approach to designing, building, and managing networks that separates the network’s control (brains) and forwarding (muscle) planes to better optimize each.”
Rather than utilize several networking applications and monitoring tools that are managed individually, SDN separates control logic to off-device computers in order to centralize network control. Software-defined networking also requires you to have a method of communication between the control plane and data plane. This new design methodology empowers you to manage network services through abstraction of lower-level functionality.
With SDN, you have a high level of flexibility in terms of dictating switches, routers, and underlying systems and how your forwarding plane handles your network traffic and relays information.
Customizable and cost-effective, SDN has become more prevalent as bandwidth has increased and applications have become more complex. With directly programmable network control, you have the power to decide how network traffic and data flow through your network.
In total, SDN streamlines the design, deployment, management, and scalability of your network while mitigating the risk of human error and automating provisioning processes.
A critical component to the design of a virtual network (such as SDN) or a physical network is the network TAP. According to Network World, “The Open Networking Foundation (ONF) announced a Sample Tap application in March 2014, and OpenFlow version 1.4 already includes a use case for configuring switches with an NPB-like functionality.” That said, it was not created with the purpose of replacing packet broker functionalities, but more so as an educational tool to help programmers gain experience with OpenFlow.
Whether network packet brokers are virtualized or not, the TAP is essential to your visibility plane and your ability to properly manage your network.
A TAP is placed between two ends of your network to pass complete packet copies of traffic flowing between devices – or in this case, between the control (SDN) and forwarding devices/software. When installed, your traffic flows through the network TAP uninterrupted.
Regardless of whether you stick with a physical network environment or go the route of SDN, your network visibility is dependent on having a TAP to connect your virtual and physical network components. Be proactive in designing your network with this critical network device. Without it, you’re risking the benefits that SDN provides.
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If the inline security tool goes off-line, the TAP will bypass the tool and automatically keep the link flowing. The Bypass TAP does this by sending heartbeat packets to the inline security tool. As long as the inline security tool is on-line, the heartbeat packets will be returned to the TAP, and the link traffic will continue to flow through the inline security tool.
If the heartbeat packets are not returned to the TAP (indicating that the inline security tool has gone off-line), the TAP will automatically 'bypass' the inline security tool and keep the link traffic flowing. The TAP also removes the heartbeat packets before sending the network traffic back onto the critical link.
While the TAP is in bypass mode, it continues to send heartbeat packets out to the inline security tool so that once the tool is back on-line, it will begin returning the heartbeat packets back to the TAP indicating that the tool is ready to go back to work. The TAP will then direct the network traffic back through the inline security tool along with the heartbeat packets placing the tool back inline.
Some of you may have noticed a flaw in the logic behind this solution! You say, “What if the TAP should fail because it is also in-line? Then the link will also fail!” The TAP would now be considered a point of failure. That is a good catch – but in our blog on Bypass vs. Failsafe, I explained that if a TAP were to fail or lose power, it must provide failsafe protection to the link it is attached to. So our network TAP will go into Failsafe mode keeping the link flowing.
Single point of failure: a risk to an IT network if one part of the system brings down a larger part of the entire system.
Heartbeat packet: a soft detection technology that monitors the health of inline appliances. Read the heartbeat packet blog here.
Critical link: the connection between two or more network devices or appliances that if the connection fails then the network is disrupted.