Abstract: A method for transmitting fragmented packets, a communication system and tunnel equipment are disclosed herein to enable fragmented packets to traverse the NAT or firewall. The method includes: the first tunnel equipment receives an IP fragmented packet and converts it into a non-fragmented packet, and transmits the non-fragmented packet to the second tunnel equipment through a UDP tunnel. The system includes: a first tunnel equipment, a second tunnel equipment, and a UDP tunnel which connects the first tunnel equipment with the second tunnel equipment. The first funnel equipment is adapted to: receive an IP fragmented packet and convert it into a non-fragmented packet, and transmit the non-fragmented packet to the second tunnel equipment through a UDP tunnel. The second tunnel equipment is adapted to receive the packet from the first tunnel equipment. In addition, a tunnel equipment is disclosed herein. Through the present invention, fragmented packets can traverse the firewall.

Abstract: The present invention discloses a method for traversing Network Address Translation (NAT) or Firewall (FW) devices, including: setting up a User Datagram Protocol (UDP) tunnel between a first device and a second device, wherein the first device and the second device are on the two sides of the NAT or FW device; and transmitting, via the UDP tunnel, a packet originated from one of the two devices to the other of the two devices through the NAT or FW device. With the method provided in the present invention, packets can traverse the NAT or FW device without any modification to the NAT or FW device.