3Com® VCX V7111 VoIP Gateway User Guide 373 When setting ANY IP to the acSNMPManagerIP (this is the older parameter, not thetable parameter), two more parameters are SET to ENABLE. snmpManagerIsUsed.0and snmpManagerTrapSendingEnable.0 are both set to 1.SNMP NAT TraversalA NAT placed between the gateway and the element manager calls for traversal solutions: Trap source port: all traps are sent out from the SNMP port (default 161). A managerreceiving these traps can use the binding information (in the UDP layer) to traverse theNAT back to the device.The trap destination address (port and IP) are as configured in the snmpTargetMIB. acKeepAliveTrap: this trap is designed to be a constant life signal from the device to themanager allowing the manager NAT traversal at all times. TheacBoardTrapGlobalsAdditionalInfo1 varbind has the devices serial number.The destination port (that is, the manager port for this trap) can be set to be different thanthe port to which all other traps are sent. To do this, use theacSysSNMPKeepAliveTrapPort object in the acSystem MIB or the ini file parameterKeepAliveTrapPort.The trap is instigated in three ways: Using an ini file parameter (SendKeepAliveTrap = 1). This ensures that the trap iscontinuously sent. The frequency is set using the 9/10 of theacSysSTUNBindingLifeTime object. After the STUN client has discovered a NAT (any NAT). If the STUN client cannot contact a STUN server.The two latter options require the STUN client be enabled (EnableSTUN). Also, oncethe acKeepAlive trap is instigated it does not stop. The manager can see the NAT type in the MIB:3Com(5003).acProducts(9).acBoardMibs(10).acSystem(10).acSystemStatus(2).acSysNetwork(6).acSysNAT(2).acSysNATType(1) The manger also has access to the STUN client configuration:3Com(5003).acProducts(9).acBoardMibs(10).acSystem(10).acSystemConfiguration(1).acSysNetworkConfig(3).acSysNATTraversal(6).acSysSTUN(21) acNATTraversalAlarm: When the NAT is placed in front a device that is identified as asymmetric NAT, this alarm is raised. It is cleared when a non-symmetric NAT or no NATreplace the symmetric one.SNMP Administrative State ControlNode MaintenanceNode maintenance for the Gateway is provided by an SNMP interface. The acBoardMIBprovides two parameters for graceful and forced shutdowns of the Gateway:
