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Kunal_Borkar_11's avatar
Kunal_Borkar_11
Icon for Nimbostratus rankNimbostratus
Mar 06, 2019

ISO 8583 Load Balancing

we have below requirement for load Balancing of ISO 8583 traffic,

 

ISO messages require special handling to determine the start and end of the messages. A message will have its first two bytes as header. In this two bytes the length of the message body will be mentioned. Hence when a load-balancer port starts listening, it has to read the first two bytes. Get the contents of these two bytes in HEX, convert it to decimal to get the length of the message body. Read till the end of the message, depending on the message length. Route the message(both header and body) to a destination internal application Server and continue listening. Please find below example,

 

Example of a complete ISO message including header and body bytes: [1,56,48, 50, 48, 48, 70, 50, 49, 67, 54, 52, 56, 49, 48, 56, 69, 49, 48, 48, 48, 56, 48, 48, 48, 48, 48, 48, 48, 48, 48, 54, 48, 48, 48, 49, 48, 48, 49, 54, 52, 54, 53, 53, 55, 51, 49, 55, 50, 52, 49, 57, 53, 53, 52, 55, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 53, 49, 48, 48, 48, 48, 48, 49, 50, 49, 48, 48, 50, 51, 56, 51, 54, 49, 54, 51, 55, 51, 52, 49, 50, 51, 48, 50, 49, 49, 50, 54, 48, 49, 49, 48, 53, 54, 48, 56, 49, 49, 48, 48, 54, 54, 50, 50, 48, 49, 56, 56, 57, 49, 50, 51, 52, 53, 54, 55, 56, 57, 49, 57, 57, 57, 56, 49, 50, 51, 52, 49, 49, 49, 49, 57, 57, 48, 56, 56, 57, 57, 48, 56, 56, 57, 84, 69, 82, 77, 73, 78, 65, 76, 79, 87, 78, 69, 82, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 67, 104, 101, 110, 110, 97, 105, 32, 32, 32, 32, 32, 32, 84, 78, 73, 78, 48, 49, 49, 48, 53, 49, 48, 48, 53, 65, 84, 77, 48, 49, 48, 50, 49, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 55, 49, 49, 49, 48, 50, 49, 57, 55, 56, 53, 53, 48, 52, 54, 49, 57, 55, 49, 50, 48, 51, 54, 52, 52, 51, 52, 49, 57, 51, 49, 54, 57, 56, 56, 55, 51, 51, 51, 56, 55, 50, 57, 55, 49, 51, 54, 50, 48, 51, 56, 48, 48, 49, 48, 48, 50, 52, 53, 48, 48, 50, 48, 48, 51, 77, 79, 66, 48, 52, 53, 48, 48, 52, 65, 66, 67, 68, 48, 53, 49, 48, 48, 53, 65, 84, 77, 48, 49]

 

First two bytes (header): [1, 56]

 

First two bytes in HEX: 0138

 

First two bytes in decimal: 312

 

Message body length: 312

 

Bytes to be sent to destination Application port : 2+312 = 314

 

Please help with I-rule and LTM configuration.

 

application delivery
iRules
LTM
  • Stanislas_Piro2's avatar
    Stanislas_Piro2
    Icon for Cumulonimbus rankCumulonimbus
    Mar 10, 2019

    You can try this code:

     

    when CLIENT_ACCEPTED {
   prevent first packet to be released to server before CLIENT DATA inspected (CLIENT_DATA Event)
  TCP::collect
}
when CLIENT_DATA {
  if {[binary scan [TCP::payload] S length] == 1 && [expr { ($length & 0xffff) +2 }] == [TCP::payload length]} {
    log local0. "This packet length meets header length value : Header value : [expr { ($length & 0xffff) }] / Packet Length : [TCP::payload length]"
     release packet to server... the data length equals the data header length value.
    TCP::release
     Allow to load balance per packet
    TCP::notify request
      prevent next packet to be released to server before CLIENT DATA inspected (loop on CLIENT_DATA Event)
    TCP::collect
  } else {
     Packet length doesn't meet Header length value... this is not a valid ISO 8583 packet.
    log local0. "This packet length doesn't meet header length value... this is not a valid ISO 8583 packet. reject the connection"
    reject
  }
}
when USER_REQUEST {
   We don't expect a response, so let's just signal one
   and detach to make oneconnect happy (message-based)
  TCP::notify response
  LB::detach
}

    This code supports oneconnect profile assigned to the virtual server and load balance to server message-based and not connection-based.

     

    • wlopez's avatar
      wlopez
      Icon for Cirrocumulus rankCirrocumulus
      Oct 26, 2022

      We tried this iRule on a virtual server with the oneconnect profile but it didn't work.

      Does anyone have a working iRule and setup to load balance ISO8583 transactions that are received through a single tcp connection on the virtual server?