Research And Implementation On The Self-Recovery Of BFD-based MPLS Network

The traditional IP network now fails to serve the need of bearer real-time service in an effective way with its best-effort service against the backdrop of ever-increasing Internet service traffic and gradually diversified network service. There is an urgent need to guarantee the network continuity and Quality-of-Service (QoS) against network fault in order to obtain ideal service availability to help the automatic detection of network failure and recovery from that failure. As the core technology for the future backbone network, Multi-Protocol Label Switching (MPLS), by means of label-swapping technique, is expected to offer the Quality-of-Service (QoS) and traffic engineering more effective and potential than ever before. The MPLS network automatically resumes the interrupted service and maintains the robustness and efficiency of the network as a whole even in the case of node failure or link failure. The self-recovery technology of MPLS network is used to protect the network feasibility and stability in terms of fault detection technique and fault recovery.It takes at least several seconds or even a couple of minutes for the current recovery mechanism of the IP-based routing protocol, thus leading to a great deal of packet loss, the bad quality of service and the degradation of network performance. Due to the traditional IP network's undesirable capability of accurate fault detection for real-time applications like voice and for lack of intermittent recovery ability below second level, it is imperative to put fault detection and repairment for network into effect in accordance with the expansion of VoIP application. The self-recovery technology of MPLS network can, in response to the network fault, offer a reaction time less than IP layer and quickly detect the network fault and recover from that fault to remain the continuity of the network service. This paper, on the basis of in-depth discussion on the fault detection technique of the MPLS network, significantly reduces the detecting time of MPLS self-recovery to millisecond level by adopting Bidirectional Forwarding Detection (BFD) as the fault detection technique of MPLS network, and by careful design and realization of MPLS BFD as well as its application into multi-core router.There needs to be a better scheme for fault recovery after the network is detected by MPLS. Of all the recovery schemes, there are two most famous ones, namely Makam and Haskin. Makam almost avoids the problem of packet reorder but suffers packets loss and relatively long protection time, while Haskin provides quick path switch but suffers severe problem of packet reorder as soon as the network traffic is redirected into the original working path to backup path after successful repair on working path. Thus, it has become the key point on how to develop a new type of fault recovery scheme so as to speed up the fault recovery while avoiding packet loss and packets disorder.This paper offers a new kind of fault recovery scheme, namely the BFD-based fault recovery scheme on the basis of the research into the existing recovery schemes. The BFD-based fault recovery scheme possesses local repair mechanism to set up backup path so that the network traffic is quickly redirected into backup path once fault occurs, thus effectively avoiding packet loss and packet delay caused by traffic switch. This paper presents a new type of solution to the problem of packet disorder, namely utilizing disorder-control-label to control packets order and to avoid packet disorder. Tested in a real experimental network, the new type of fault recovery scheme is proved to be quick in fault recovery and effective in avoiding packet loss and packet delay.