36. Overlay Networks

It was not too long ago that people just spoke about the network without qualifiers. Today, however, you typically hear about the network in terms of an overlay network or underlay network, especially with regard to the data centers and clouds. In cloud-based data centers, overlays act as independent networks that sit on top of the physical infrastructure, which is the underlay network, but they also provide the means to provision and orchestrate networks alongside other virtual resources.

This all starts to sound like software-defined networking (SDN) or network virtualization (NV), but you must be careful not to confuse terms, because overlay networks are not necessarily either of these technologies. For instance, a network ...

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