Managing network equipment in the data center often requires a direct serial port connection. There are special servers (Console Servers) made for this purpose that allow remote access to your serial terminal (console) lines via your network (ip management of serial port devices). Care must be used in securing each console server to limit physical and IP access. Using a separate management network, firewall rules, secure connections, strong passwords, good locks (physical access control systems), alarm systems, and other security measures are recommended.
When low-level things break in the data center, a console server is one of the most helpful tools to have available. Add one to your network rack if it fits your budget. A high-level description of “console server” is available on Wikipedia at http://en.wikipedia.org/wiki/Console_server.
Some vendors to consider include Avocent (formerly Cyclades) Advanced Console Server (ACS) or Perle IOLAN Serial Terminal Server (STS). Prices for a 1U console server seem to start around $900 (4-port budget model). Cisco serial terminal “access server” products can be used for terminal services too. The discontinued 2509/2511 are available for low prices on eBay, but you won’t get Cisco support or security software updates (support ended in 2005). For a supported Cisco product, the Network Module (NM) line cards NM-16A and NM-32A can be used in newer routers for serial terminals (NM-16A sixteen port card seems to cost around $2,750).