Virtual Path Hopping to overcome Network Failures due to Control Plane Failures in Connection Oriented Networks

摘要

Real time traffic will be a predominant traffic type in the next generation communication IP networks and the future applications will demand for 100% reliability and availability of networks. The guarantees of QoS expected can be achieved by connection oriented networks such as MPLS. The control plane and the data plane of MPLS are logically separated. Therefore any failures in the control plane not necessarily should affect the communication sessions in the data plane. Label Distribution Protocol (LDP) which is preferred over RSVP as a control plane protocol in MPLS, uses TCP in the transport layer for most of its message transmissions. TCP will reset all the participating peers, at any terminations of LDP sessions, leading the applications to terminate the corresponding data plane communications. If the Keep Alive timers of the LDP peers expire without receiving Protocol Data Units (PDU) from the neighboring peers, it terminates the LDP session resulting in a network failure due to control plane failure. None of the existing restoration schemes distinguish this type of control plane failures from the normal data plane path/link failures. It is found that about 50% of the network failures are of this type and if they can be avoided without disturbing the data plane, it will improve the availability and the reliability of the connection oriented networks drastically. In this paper a novel idea of Virtual Path Hopping (VPH) is proposed, which can avoid all the control plane failures from affecting the communications in the data plane. The computer simulations performed, prove that it is possible to avoid about 50% re-routings due to failures in the data plane and this explains that the control plane failures are looked after by the VPH concept.