Apparatus for controlling tunneling loop detection

Abstract

Disclosed is a technique whereby a packet transferring apparatus (particularly, a tunnel entry point made to carry out packet encapsulation) becomes capable of detecting a tunneling loop signifying that a packet loops along the same route while undergoing encapsulation. With this technique, at packet transfer, a loop detection module of a router according to the present invention stores a TEL value (value of tunnel encapsulation limit for limiting the number of times of duplication of tunnel) set in an encapsulation header of this packet or stores a TEL value set in an encapsulation header of a packet sent back as an ICMP error. In addition, the loop detection module analyzes an increase / decrease variation pattern of the stored TEL value relative to time and, in a case in which the pattern agrees with a unique pattern (sawtooth-like pattern) appearing at the occurrence of a tunneling loop, estimates that a tunneling loop has occurred.

Description

technical field [0001] The invention relates to a device for controlling tunneling loop detection for controlling packet encapsulation (packet tunneling) in a packet-switched data communication network. Background technique [0002] A large number of protocols belonging to the Internet protocol suite utilize packet encapsulation (or packet tunneling). Packet encapsulation in IPv6 (Internet Protocol Version 6) is mainly defined in Non-Patent Document 1 below. [0003] For example, in a virtual private network (VPN), the utilization of tunneling technology occurs whereby two or more networks at different locations can be connected to each other in order to establish a large-scale private network. [0004] Also, in case of mobility support for Mobile IPv6 (MIPv6), the mobile node is always reachable at its own home address by using tunneling between the mobile node and the home agent. [0005] In the case of IPv6 Network Mobility Support (NEMO), a mobile router establishes a ...

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Problems solved by technology

[0045] Moreover, the method disclosed in Patent Document 1 is not suitable for routers that process several thousand packets per second

[0046] Furthermore, with the methods disclosed in Patent Documents 2 and 3, the following problem occurs: the computational cost required to go to great lengths to prevent the occurrence of loops is not worth it, especially, in the case where the probability of occurrence of loops is rather low

For this reason, tunneling protocols are not suitable for complete and complex loop avoidance mechanisms

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