Abstract: In order to improve safety and reliability of SGSN, core equipment of global system for mobile communication for railway GSM-R data service in railway mobile communication system was studied,activation process of PDP, GTP version of SGSN equipment and setting of PDP activation timer in GSM-R network were analyzed.According to actual operation of current network and fault case analysis, processing mechanism of parameters was studied in detail, and parameter combination scheme and protocol coordination with other equipment were explored.The results show that fault between SGSN and GGSN can be effectively reduced by reasonable configuration of SGSN GTP and PDP activation timer.Avoid service impact caused by network delay and protocol mismatch between devices, and improve the safety and stability of network.

Key words: serving GPRS support node (SGSN), timer, global system for mobile communication for railway(GSM-R), data traffic, packet data protocol (PDP), general wireless packet service tunneling protocol (GTP)