It is Easier to Move a Problem than Solve it (RFC1925, Rule 6)

Early on in my career as a network engineer, I learned the value of sharing. When I could not figure out why a particular application was not working correctly, it was always useful to blame the application. Conversely, the application owner was often quite willing to share their problems with me, as well, by blaming the network.

A more cynical way of putting this kind of sharing is the way RFC 1925, rule 6 puts is: “It is easier to move a problem around than it is to solve it.”

Of course, the general principle applies far beyond sharing problems with your co-workers. There are many applications in network and protocol design, as well. Perhaps the most widespread case deployed in networks today is the movement to “let the controller solve the problem.” Distributed routing protocols are hard? That’s okay, just implement routing entirely on a controller. Understanding how to deploy individual technologies to solve real-world problems is hard? Simple—move the problem to the controller. All that’s needed is to tell the controller what we intend to do, and the controller can figure the rest out. If you have problems solving any problem, just call it Software Defined Networking, or better yet Intent Based Networking, and the problems will melt away into the controller.

Pay no attention to the complexity of the code on the controller, or those pesky problems with CAP Theorem, or any protests on the part of long-term engineering staff who talk about total system complexity. They are probably just old curmudgeon who are protecting their territory in order to ensure they have a job tomorrow. Once you’ve automated the process you can safely ignore how the process works; the GUI is always your best guide to understanding the overall complexity of the system.

Examples of moving the problem abound in network engineering. For instance, it is widely known that managing customers is one of the hardest parts of operating a network. Customers move around, buy new hardware, change providers, and generally make it very difficult for providers by losing their passwords and personally identifying information (such as their Social Security Number in the US). To solve this problem, RFC8567 suggests moving the problem of storing enough information to uniquely identify each person into the Domain Name System. Moving the problem from the customer to DNS clearly solves the problem of providers (and governments) being able to track individuals on a global basis. The complexity and scale of the DNS system is not something to be concerned with, as DNS “just works,” and some method of protecting the privacy of individuals in such a system can surely be found. After all, it’s just software.

If the DNS system becomes too complex, it is simple enough to relieve DNS of the problem of mapping IP addresses to the names of hosts. Instead, each host can be assigned a single host that is used regardless of where it is attached to the network, and hence uniquely identifies the host throughout its lifetime. Such a system is suggested in RFC2100 and appears to be widely implemented in many networks already, at least from the perspective of application developers. Because DNS is “too slow,” application developers find it easier to move the problem DNS is supposed to solve into the routing system by assigning permanent IP addresses.

Another great example of moving a problem rather than solving it is RFC3215, Electricity over IP. Every building in the world, from houses to commercial storefronts, must have multiple cabling systems installed in order to support multiple kinds of infrastructure. If RFC3215 were widely implemented, a single kind of cable (or even fiber optics, if you want your electricity faster) can be installed in all buildings, and power carried over the IP network running on these cables (once the IP network is up and running). Many ancillary problems could be solved with such a scheme—for instance, power usage could be measured based on a per-packet system, rather than the sloppier kilowatt-hour system currently in use. Any bootstrap problems can be referred to the controller. After all, it’s just software.

The bottom line is this: when you cannot figure out how to solve a problem, just move it to some other system, especially if that system is “just software,” so the problem now becomes “software defined. This is also especially useful if moving the problem can be accomplished by claiming the result is a form of automation.

Moving problems around is always much easier than solving them.