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,
10-Mar-201910:51 - last edited on 21-Nov-202221:35 by JimmyPackets
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.
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?
