This excerpt is from David Hucaby CCNP Switch - page 356, "when the local SPAN is enabled, STP is disabled on the destination port. This allows STP BPDUs to be captured and monitored but also allows the possibility for a bridging loop to form. NEVER CONNECT A SPAN SESSION'S DESTINATION PORT BACK INTO AN ACTIVE NETWORK". If STP is disabled why can't we connect port back and what disruption will it do to the network?