mahir:

Sometimes it’s good to remember the oldies. One of the most important network diagram in the modern history designed by researcher Paul Baran in RAND Corporation. 

Baran suggested a third alternative—a distributed network—a communication network which will allow several hundred major communications stations to talk with one another after an enemy attack. (Baran, Rand Memorandum 3420-PR, CH.1) A distributed network would have no centralized switch. Each node would be connected to several of its neighboring nodes in a sort of lattice-like configuration. Therefore, each node would have several possible routes to send data. If one route or neighboring node was destroyed, another path would be available.