Cisco GPRS Tunneling Protocol T3 Tunnel Timer

1.3.6.1.4.1.9.9.188.1.1.3

When the GSN behaves as SGSN, the T3-TUNNEL timer is used for mobility management. When a roaming MS moves from one SGSN(Old SGSN) to a another SGSN(New SGSN), this timer is started by the 'Old SGSN'. While the timer is running, the T-PDUs received by the 'Old SGSN' (from the GGSN), and any buffered T-PDUs are forwarded to the 'New SGSN'. When the GSN behaves as GGSN, the GGSN starts this timer after receiving a Update PDP Context request message from 'New SGSN'. An Update PDP context request shall be sent by SGSN as part of mobility management intimating that MS has moved to this SGSN. While the timer is running, the GGSN will not be forwarding any PDUs to the requesting 'New SGSN'.