iRules and nPath?

Perhaps there's more complexity there than you let on, but a NAT should not be involved in proxying the connection to the real servers/pool members: NAT provides one-to-one translations for direct connections, and typically does not play into the load balancing traffic flows.

 

 

LTM virtual servers by default send the original client request to the selected pool member's IP:port without changing anything else. Client address, host header and URI are unmodified. Only destination IP and port are changed.

 

 

If you've configured a SNAT (to translate the client/source address before proxying to the pool member), the response traffic from that pool member must traverse the BIG-IP to reverse the SNAT before the response is returned to the client.

 

 

If you've configured an iRule that performs a SNAT or requires any other response processing (such as HTTP_RESPONSE event logic), the response traffic must traverse the BIG-IP.

 

 

A primary feature of nPath configuration is that response traffic does NOT traverse the BIG-IP

 

 

**An nPath configuration is fully compatible with a standard virtual server referencing a server pool, as long as destination address translation and port translation are DISABLED.

 

 

**nPath is NOT compatible with SNAT, since SNAT traffic must return to BIG-IP.

 

 

**nPath is compatible with iRules that never need to see the response traffic

 

 

Hope that answers your question.

 

 

/deb