In a perfect world, network engineers and people who design and manage networks should focus on what they want the network to achieve instead of the device-level interactions. In my first job as an intern for a local ISP, wide-eyed and excited, I received my first assignment to install a router on a customer's site to turn up their fractional frame relay link (remember those?). How would I do that? I asked. I was handed a standard operating procedure for turning up frame relay links. I went to the customer site, blindly typed in the commands and looked at the green lights flash, and then I happily packed my bag and patted myself on the back for a job well done. As exciting as that first assignment was, I did not fully understand what I was doing. I was simply following instructions without thinking about the implication of the commands I was typing in. How would I troubleshoot something if the light was red instead of green? I think I would have called back to the office.
Of course, network engineering is not about typing in commands onto a device, but it is about building a way that allows services to be delivered from one point to another with as little friction as possible. The commands we have to use and the output that we have to interpret are merely a means to an end. I would like to hereby argue that we should focus as much on the intent of the network as possible for an intent-driven networking and abstract ourselves from the device-level interaction on an as-needed basis.
In using an API, it is my opinion that it gets us closer to a state of intent-driven networking. In short, because we abstract the layer of a specific command executed on destination device, we focus on our intent instead of the specific command given to the device. For example, if our intend is to deny an IP from entering our network, we might use access-list and access-group on a Cisco and filter-list on a Juniper. However, in using API, our program can start asking the executor for their intent while masking what kind of physical device it is they are talking to.