In essence you will need to create a script in your language / shell of choice to interrogate your server for currently loaded networking information, compare it to any changes made to the interfaces, routing tables, config files, and any other receptacle of networking options, and then run logic on the differences to determine if conditions exist that break access to any or all networks.
Since each networked device has a plethora of different interfaces, routes, protocols, physical and virtual infrastructure that are unique to your scenario, it's not exactly as easy to create a configtest as it is with Apache. (I use the word "easy" in relation to Apache with my filiform papillae stifly impressed against my buccal region)
In short, you'll be looking at creating a script on your own that checks for the conditions that you are most concerned with. And if you were intimately familiar enough with the networking resources on your servers to be able to make that kind of script, you'd probably not need that kind of script. Okay, that's not exactly true, but it sounded good.
How are good are you with perl?