till which layer the loopback packet goes . i mean to ask that the lowest layer till which packet travel and then come back. I read that it goes to data link layer . but is the point to send it to data link layer as the address 127 is know at the network layer. at the same page i also read that it will return as the address 127 will be known . which is know at network layer . so i m confussed till which point the packet will go .