Generic Routing Encapsulation

from The Free On-line Dictionary of Computing (8 July 2008)

Generic Routing Encapsulation
GRE

   <networking, protocol> (GRE) A {protocol} which allows an
   arbitrary network protocol A to be transmitted over any other
   arbitrary network protocol B, by encapsulating the {packets}
   of A within GRE packets, which in turn are contained within
   packets of B.

   Defined in {RFC 1701} and {RFC 1702} (GRE over IP).

   (1998-07-19)