Fate-sharing places state needed by a communicating endpoint with that endpoint, so that failure of an unrelated forwarding component need not erase the state of an ongoing exchange. This can help communication recover after a route change when a path becomes available again. It does not mean every router lacks state or that communication can survive loss of all paths.[ref]
The design philosophy of the DARPA Internet protocols by David D. Clark. §4: survivability and placement of essential connection state
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