* The abstract world of virtual circuits
Over the past 30 or so years, we’ve undergone a drastic metamorphosis from a “physical” to a “virtual” reality in almost all phases of networks. Sure, there always has been and always will be some form of a “real” network at “Layer 1” based on light pulses on fiber, electrical changes in a “wire” of some form, or a radio signal of some form. But beyond that, we’re becoming increasingly virtual at all networking layers.
Many of you – perhaps half of our readers – may have never lived in the “real” world of telecommunications. No, that isn’t intended as a slam on your experience. But the reality of the situation is that the industry underwent a fundamental transformation as it moved from “real” time-division multiplexing as the primary networking form to the “virtual” world of packet-switched services.
We’re making this “real” vs. “virtual” distinction based largely on whether the user/purchaser of the service has unique, dedicated access to the transmission capability or whether the transmission capability is based on some form of virtual circuit. With moving to the use of “virtual circuits,” the user traded a (relatively) fixed path with (relatively) fixed resources for a pair of addresses – and a hope/belief/expectation that the provider of the service would transport information reliably from one location to another.
At the WAN level, this transition meant the need for both a new level of trust and a new management mindset. With “real” circuits, it was easy to define whether a service was delivered or not. It either “worked” or it didn’t. And something as simple as an LED could be used to indicate whether physical connectivity existed.
In the abstract world of virtual circuits, however, the entire concept of connectivity changed. Now there are packets (of some format) submitted to a network, and there is no fixed, predefined path. And while the benefits of virtual circuits in virtual networks are obvious, they do indeed take a different level of management and a totally different mind-set for troubleshooting. For instance, when connectivity is “lost” between two points, one must look at various possible paths, which path failed, and why an alternate path was not chosen.
But even more likely, a “failure” will not be a binary event. Rather than having a complete loss of service, degraded service – which will probably be degraded on a sporadic basis – is much more likely. Consequently, increasingly complex and sophisticated management tools are needed to ensure that you’re getting the level of service that you’re paying for.
The good news is that these tools abound, and we’ll discuss some of these in the next newsletter.
