The VMware Smart Assurance Service Assurance Manager Adapter Platform User Guide describes the operation of an SNMP Trap Adapter configured as a trap exploder. The operation is based on the parameter settings in the trapd.conf file described in “Trap adapter configuration file: trapd.conf” on page 85.

Note:

A trap exploder is also known as a “trap forwarder.”

In a VoIP Availability Manager deployment, the SNMP Trap Adapter configured as a trap exploder receives SNMPv1, v2c, and v3 traps from the managed IPv6 or IPv4 network systems on its trap listening port (9000 by default) and:

  • Forwards copies of received Avaya and Nortel VoIP traps to VoIP Availability Manager—to be used by VoIP Availability Manager for analysis purposes.

  • Forwards copies of received network traps to IP Availability Manager—to be used by IP Availability Manager for analysis purposes.

  • Optional: Forwards copies of received useful or interesting VoIP traps to the VoIP Notification Trap Adapter—to be used by users for informational purposes.

  • Optional: Forwards copies of received useful or interesting non-VoIP traps to the SNMP Trap Adapter configured as a trap receiver—to be used by users for informational purposes.

    For a managed network environment containing dual-stack devices, the SNMP Trap Adapter might receive IPv6 and IPv4 traps from the same device.

    The SNMP Trap Adapter configured as a trap exploder authenticates and decrypts received SNMPv3 traps, converts them to SNMPv2c traps, and forwards the SNMPv2c traps to the configured destinations. The SNMP Trap Adapter uses the authentication and privacy credentials obtained from a seed file (typically a copy of the seed file maintained by IP Availability Manager for discovery purposes) to authenticate and decrypt SNMPv3 traps.

    When a trap arrives, the SNMP Trap Adapter translates the trap in accordance to SNMP Trap Adapter translation of incoming traps to forwarded traps and reads the uncommented FORWARD entries in the trapd.conf file to determine which destinations should receive the forwarded trap. When the criteria of the trap matches the criteria of a FORWARD entry, the SNMP Trap Adapter sends a copy of the forwarded trap to each destination specified in the FORWARD entry.

     
Table 1. SNMP Trap Adapter translation of incoming traps to forwarded traps

Incoming trap message version

Forwarded trap message version

Comments or conditions requiring special processing

v1

v1

If the agent-addr field in an incoming trap is 0.0.0.0 (indicating an invalid IPv4 address) and the source IP address in the IP packet header is IPv4, the adapter discards the trap.

If the agent-addr field in an incoming trap is 0.0.0.0 and the source IP address in the IP packet header is IPv6, the adapter adds two VMware Smart Assurance private variable-bindings (varbinds) named smSnmpTrapInetAddressType and smSnmpTrapInetAddress to the varbind list of the forwarded trap. Together, the private varbinds hold the source IPv6 address of the original trap.

v2c

v2c

The adapter sets a standard varbind named snmpTrapAddress.0 to the value of the source IP address in the IP packet header:

  • If the snmpTrapAddress.0 value is 0.0.0.0 (indicating an invalid IPv4 address) and the source IP address in the IP packet header is IPv4, the adapter discards the trap.

  • If the snmpTrapAddress.0 value is NOT 0.0.0.0 (indicating a valid IPv4 address), the adapter adds the snmpTrapAddress.0 varbind to the varbind list of the forwarded trap. The varbind holds the source IPv4 address of the original trap.

  • If the snmpTrapAddress.0 value is 0.0.0.0 and the source IP address in the IP packet header is IPv6, the adapter adds two VMware Smart Assurance private varbinds named smSnmpTrapInetAddressType and smSnmpTrapInetAddress to the varbind list of the forwarded trap. Together, the private varbinds hold the source IPv6 address of the original trap.

v3

Because the agent-addr field in an SNMPv1 trap message can represent only IPv4 (32-bit) addresses, the SNMP agent on an IPv6 device will set the agent-addr field in a generated v1 trap to the null IP address 0.0.0.0.

Similarly, because the standard trap-forwarding MIBs can represent only IPv4 addresses, any trap forwarder processing a v2c or v3 trap received from an IPv6 device will set the standard snmpTrapAddress.0 varbind to the null IP address 0.0.0.0.

In either case, the traditional trap forwarder will discard the trap because the source device address is not preserved in the forwarded trap. Forwarding such a trap would be futile because the target trap receiver would not be able to determine the source device address of the trap.