By adding the physical infrastructure to your network management system, you add location information that may not be available otherwise. You want to be sure that the system is dynamic (does not require a human to input changes). The changes should be discovered in real time adding to the security features of the system. In areas on a network where mobile devices are used, this is a great aid for troubleshooting, etc. You can’t fix it if you don’t know where it is! It also is a wonderful tool when you have responsibility for several remote sites; have to maintain documentation for compliance; etc. I would suggest checking out MapIT. It is feature rich, very green (low power), and will provide the benefits listed above.