LT groups and dynamic LT allocation

In SWIFT terminology, the first 8 characters of a 9-character LT name are called a destination. LTs that share a destination can be combined into LT groups. Using LT groups has the following advantages:
  • You can arrange for several LTs to share a common outbound-message workload. For example, if you create a group containing the LTs IBMADEFFA and IBMADEFFB, each of these LTs can process messages that have the FIN destination IBMADEFF with the LTID A or B. If one session fails, the other can process the outbound messages that the other LT is unable to process, thereby increasing overall availability.

    It can happen that several LTs in an LT group try to process the same outbound message. Only one LT will be able to process the message; the others will each register a failed attempt and will try to process other outbound messages. If an LT is unable to obtain and process an outbound message before it exhausts its allotted number of retry attempts, its session is aborted. To reduce the likelihood of this happening, ensure that at most four of the LTs that comprise an LT group are engaged in active sessions at the same time.

  • You can create LTs that are to be used exclusively by applications, and that are independent of the LTs used to establish sessions. For example, you can configure an LT with the ID IBMADEFFX, and add it to the same group as IBMADEFFA and IBMADEFFB. Applications specify that a message is to be processed by the LT IBMADEFFX, but the message is processed by IBMADEFFA or IBMADEFFB. This provides you with a way to change or add LTs without having to update your application code.

You can use LTs that are not in an LT group concurrently with LTs that are. Using LT groups does not affect the processing of inbound messages.

To increase availability on the receiving side, you can share delivery subsets. This capability can be activated by means of SWIFTNet system messages. For more information, refer to SWIFT User Handbook.

If an LT stops due to an error, any outbound messages being processed by that LT are locked. To send locked messages, either:
  • Re-establish the session
  • Issue the reset command to free the message for sending by another LT of the same group

If you change the name of an LT group, remember that messages stored in the outbound application message store (table DNF_OAMS) that contain the old LT group name are not processed until the reset command is issued.