a) Application Transport Network Data Link Physical b) Application : message Transport : segment Network : datagram/packet Data Link : frame Physical : bit stream c) End-system: up to Application Layer d) Router: up to Network layer e) Link layer switch: up to data link layer Solution a) Application Transport Network Data Link Physical b) Application : message Transport : segment Network : datagram/packet Data Link : frame Physical : bit stream c) End-system: up to Application Layer d) Router: up to Network layer e) Link layer switch: up to data link layer.