Use iRules to query number of active connections against a node

A few additional things to consider:

1. A "node" is simply an IP address, while a (pool) "member" is defined by an IP and port/service. If you wanted to know the number of connections to a node on a given port, then you'd be specifying a pool member.

    

2. There is no functionality, currently, within iRules to see the number of connections to a given node or member, so any solution would likely require diving into the management plane from the iRule.

    

3. There are a number of ways to do the above, from iStats, to some method of updating a session table entry. In any case, you would need some asynchronous management plane process to update that data, which means it would never be "real time", and probably not so effective given that you're looking for a number of active, transient TCP connections.

    

4. While this is certainly possible, I would never recommend it. Reaching into the management plane from an iRule for a piece of information, randomly and seldomly may be okay, but doing so in every HTTP request would probably decimate the memory usage of the management plane.