User`s manual

Mediant 2000 & TP-1610 & TP-260
SIP User's Manual 326 Document #: LTRT-68805
15.10 SNMP NAT Traversal
A 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 manager
receiving these traps can use the binding information (in the UDP layer) to traverse
the NAT 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
the manager allowing the manager NAT traversal at all times. The
acBoardTrapGlobalsAdditionalInfo1 varbind has the device’s serial number.
The destination port (i.e., the manager port for this trap) can be set to be different than
the port to which all other traps are sent. To do this, use the
acSysSNMPKeepAliveTrapPort object in the acSystem MIB or the ini file parameter
KeepAliveTrapPort.
The Trap is instigated in three ways:
• Via an ini file parameter (SendKeepAliveTrap = 1). This ensures that the trap is
continuously sent. The frequency is set via the 9/10 of the
acSysSTUNBindingLifeTime object.
• After the STUN client has discovered a NAT (any NAT).
• If the STUN client cannot contact a STUN server.
Note: The two latter options require the STUN client be enabled (EnableSTUN).
Also, once the acKeepAlive trap is instigated it does not stop.
 The manager can view the NAT type in the MIB:
audioCodes(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:
audioCodes(5003).acProducts(9).acBoardMibs(10).acSystem(10).acSystemConfigura
tion(1).acSysNetworkConfig(3).acSysNATTraversal(6).acSysSTUN(21)
 acNATTraversalAlarm: When the NAT is placed in front a device that is identified as
a symmetric NAT, this alarm is raised. It is cleared when a non-symmetric NAT or no
NAT replace the symmetric one.