Packet CPU usage remains consistently at 100%
High Loopback traffic is observed on the node

Problem Cause

1. The appliance obtains the server’s MAC address from the monitor bound to the service. However, custom user monitors (monitors of type USER), which use scripts stored on the NetScaler appliance, do not learn a server’s MAC address. If you use only custom monitors in a DSR configuration, for each request the virtual server receives, the appliance attempts to resolve the destination IP address to a MAC address (by sending ARP requests). Because the destination IP address is a virtual IP address owned by the NetScaler appliance, the ARP requests always resolve to the MAC address of the NetScaler interface. Therefore, all traffic received by the virtual server is looped back to the appliance. If you use user monitors in a DSR configuration, you must also configure another monitor of a different type (for example, a PING monitor) for the services, ideally with a longer interval between probes, so that the MAC address of the servers can be learned.