Simulation of the SCTP Failover Mechanism
Some features of SCTP provide opportunities for creating redundancies for signalling over IP networks. This paper presents the behaviour of SCTP in failover scenarios, based on literature review and simulations. Simulations were carried out using NS2 in a multi-homing environment. It was found, as expected, that when failover took place, the undelivered chunks were retransmitted to the secondary path while new messages were still transmitted to the primary path until the error count was exceeded whereupon the primary path was declared inactive and a new primary path was chosen. The simulations raised some concerns regarding the duration of failover for different PRL values. *
On the Use of SCTP in Failover-Scenarios
The new general purpose transport protocol SCTP (Stream Control Transmission Protocol) has been developed for transport of signaling data, such as Signaling System No. 7 MTP level 2 or 3 user primitives, over IP networks. Since this application has especially high requirements towards the underlying transport protocol concerning reliability and fast recognition and recovery from failures, SCTP-based transmission must provide a high degree of network level fault tolerance. In our contribution we look at a typical link failure scenario in a multi-homed setup, and investigate two options for fast recovery from such an event, namely seamless SCTP switch-over, and a user level switch-over as has been suggested for the MTP Level 2 peer adaptation layer. Moreover, we will analyze necessary parameter settings for fast recovery from the failure situation. 1
Prediction of a representative point for rail temperature measurement by considering longitudinal deformation
Monitoring rail temperature is very important for determining the safe running speed of trains and to prevent buckling. In general, the maximum variation of the internal rail temperature can be >7 ℃ depending on the point of measurement. However, there is as yet no sufficient information about how to predict the measurement point to represent the thermal deformation due to temperature distribution. In this study, the authors report a new point, called the representative measurement point, at which the rail temperature can be measured. This point considers the average deformation of the rail through structural analysis by adopting experimental and actual rail temperature data. The authors designed and installed a measurement system similar to an actual rail environment. Using the system, various data were acquired (internal/surface rail temperature and weather data) for 10 months. On the basis of these data, an analysis was done to calculate the average deformation point through thermal analysis. Finally, the representative measurement point was proposed as the position at which the average deformation point converges regardless of weather or seasons. The authors believe that the method described herein is advantageous in that it could be used in a high-accuracy temperature-monitoring system and for predicting thermal deformation and buckling.