STP prevents loops by blocking redundant paths, but misconfigurations or STP timer changes can cause loops to reform unexpectedly. Our existing design is quite simple, it consists of several switches acting as layer 2 (around 6-7) and all of them are connected to a switch through single interface trunk ports. This switch is connected to a firewall which is the gateway for all VLANS defined, which are extended in all the. The loop prevention feature of most switches is "Rapid Spanning Tree Protocol" or RSTP. It's normally impossible to get a bridging loop without another switch at the end. I have recently been told by a consultant that access layer loops can be prevented without spanning tree on host ports by using Layer 3 routing.
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