ES-4024A Series Switch Support Notes
2. Filtering Database Instability:
When multiple copies of a frame arrive at different ports of a switch, the MAC entry instability in Filtering Database will occur.
1.Host sends an unicast frame to Router (source MAC address is Host's MAC, destination MAC address is Router's MAC). Both Switch A and Switch B will receive this frame and learn MAC address of Host on Port 2.
2.Switch A has not yet learned the MAC address of Router. So Switch A will flood a copy of the received frame to Segment B.
3.When the copy of the frame from Switch A arrives at Switch B, Switch B will remove the first entry (Host MAC address on Port 2) in Filtering Database and add a new mapping of Host MAC address on Port 1. Switch B incorrectly learn Host MAC address on Port 1. Switch B can't forward frames properly because the instability of mapping MAC address to Port.
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