Why Does the SPAN Session Create a Bridging Loop?
The creation of a bridging loop typically occurs when the administrator tries to fake the RSPAN feature. Also, a configuration error can cause the problem. This is an example of the scenario: There are two core switches that are linked by a trunk. In this instance, each switch has several servers, clients, or other bridges connected to it. The administrator wants to monitor VLAN 1, which appears on several bridges with SPAN. The administrator creates a SPAN session that monitors the whole VLAN 1 on each core switch, and, to merge these two sessions, connects the destination port to the same hub (or the same switch, with the use of another SPAN session). The administrator achieves the goal. Each single packet that a core switch receives on VLAN 1 is duplicated on the SPAN port and forwarded upward to the hub. A sniffer eventually captures the traffic. The only problem is that the traffic is also reinjected into core 2 through the destination SPAN port. The reinjection of the traffic int
