Soundbite: How NGNs become legacy

"New networks are born with a simplicity that gives them a natural advantage to serve the changing nature of traffic. To achieve unification and meet new traffic demands, designers, often with different objectives, begin to make changes to expand the base technology, and thereby increase the complexity of the new network. As each change is made, the network begins to be weighed down by its own success. Every design choice removes a degree of freedom, solving an immediate problem but eliminating potential solutions to other problems that lie in the future. Then, once again, the nature of traffic changes, and the entropy of the network makes it brittle and incapable of flexing to meet the new end. The ageing next-generation network is recast as a legacy network, only suited to old traffic types."

G Keith Cambron, president and CEO of AT&T Labs, Inc., who calls such a force of network transformation, network entropy. Source: IEEE Communications magazine, Oct 2006.