I'm looking for some suggestions as to software I can use to "map out" the numerous inter-dependencies between our large(ish) infrastructure base - the overall aim is to understand the impact of a failure to one or more of the components - be it a Server, Core Switch, WAN link, DNS, IIS etc., etc.
Some background: We've currently got quite a diverse range of both hardware and software out in the field with several hundred servers, several thousand users, numerous geographically separated offices most of which depend upon several 'hub' sites for delivery of various applications/DBs. Obviously, there are numerous WAN links in the mix, many critical applications depend upon multiple geographically disperse servers to function fully and there's the complication of the glue that binds the rest of the infrastructure together such as our DNS config, the Directory Service, links to the outside world.. While some of the inter-dependencies are obvious, some aren't or, at least, are difficult to quantify.
I'd like to be able to 'describe' the relationships and dependencies between two or more services and, ideally, the 'software' would give a visual representation of the same along with showing/indicating the effect of a specific failure in the chain.
Answer wise, I'm looking for recommendations based upon specific prior practical experience, rather than the results of a quick Google search! Also, note that I'm NOT looking for something that will traverse our network infrastructure and build a map based on subnet etc., I've already got that. The inter-dependencies of the hardware AND software & the ability to manually 'relate' disparate components are the critical things here..