Irule Switch statment & Datagroup question

It selects a single node based on the client source IP. Concretely, if the source IP from the client is "10.10.10.10" the call to class match matches the first record (the record with the key "10.10.0.0/16"). The -value flag tells the class command to return the record value if there is a match (or the empty string if there is no match). So, in this example case, the variable PAN_node is set to "A1" (the value of the matching class record). The switch matches "A1", so the command node 10.29.170.5 executes. This instruct the load-balancing engine to specifically proxy (or forward, depending on the Virtual Server type) to that node.

In Tcl, a switch does not fall through like it does in C. The code block for the first matching case is executed, then the switch terminates (unless '-' is substituted in place of the code block, which is not the case here).