Built and personally maintained: the as-built record of every switch, router, fiber interconnection unit, port and patch in the main data center, carried to revision 21 and kept current through the consolidation.
The identifier is the location
The foundation is a naming convention in which the name tells you where the thing is. MDC.DTC.NR7.R1.S.01 resolves to main data center, downtown campus, network row 7, rack 1, switch 1. Nothing has to be looked up to know where to walk.
On top of that sits a full path notation, stringing source device and port, jumper type, and destination device and port into a single line — and recorded in both directions. That redundancy is deliberate. A technician standing at either end of a link reads the same fact rather than inferring it from the other end’s entry, and the two directions disagreeing is itself a signal that something changed and was not written down.
The record ran to roughly 330 identified devices, ports and patch positions across ten rows and 33 fiber interconnection units, over a 6509 VSS core pair, 4503 distribution and 3750 stacks, with the layer 2 and layer 3 port-channels between them.
Why this is the document that matters
Most estates have a logical diagram and a spreadsheet that stopped being true some years ago. Both are usually accurate about intent and silent about reality.
The physical layer is where an outage actually happens. A strand is pulled, a patch is moved during a late-night change and put back one position over, a port is reused because it looked free. None of that shows up on a logical diagram, and all of it shows up at two in the morning. A room where nobody can say with certainty which strand goes where is a room that cannot be changed safely, which in practice means a room that stops being changed at all until something forces the issue.
Revision 21 is the point. The value is not in having drawn it once; it is in fifteen years of somebody actually updating it.
Outcome
A room where any technician could say with certainty which strand went where — which is what makes a room safe to change.