Editing Ethernet (section)

===Switching loop===
{{main|Switching loop}}
A switching loop or bridge loop occurs in [[computer network]]s when there is more than one [[Layer 2]] ([[OSI model]]) path between two endpoints (e.g. multiple connections between two [[network switch]]es or two ports on the same switch connected to each other). The loop creates [[broadcast radiation|broadcast storms]] as broadcasts and [[multicast]]s are forwarded by switches out every [[Computer port (hardware)|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.<ref>{{Cite web|title=Layer 2 Switching Loops in Network Explained|url=https://www.computernetworkingnotes.com/ccna-study-guide/layer-2-switching-loops-in-network-explained.html|access-date=January 8, 2022|website=ComputerNetworkingNotes|language=en-gb|archive-date=January 8, 2022|archive-url=https://web.archive.org/web/20220108032858/https://www.computernetworkingnotes.com/ccna-study-guide/layer-2-switching-loops-in-network-explained.html|url-status=live}}</ref>

A physical topology that contains switching or bridge loops is attractive for redundancy reasons, yet a switched network must not have loops. The solution is to allow physical loops, but create a loop-free logical topology using the SPB protocol or the older STP on the network switches.{{citation needed|date=April 2020}}