 The loop creates broadcast storms as broadcasts and multicasts are forwarded by switches out every port, the switch or switches will repeatedly rebroadcast the broadcast messages flooding the network.Since the Layer 2 header does not support a "time to live" (TTL) value, if a frame is sent into a looped topology, it can loop forever.A physical topology that contains switching or bridge loops is attractive for redundancy reasons, yet a switched network must not have loops.