Static Virtual LANs (VLANs)

Multiple VLAN Considerations

drops the packet. This is not a problem for a switch with a multiple forwarding database because the switch allows multiple instances of a given MAC address; one for each valid destination. However, a switch with a single forwarding database allows only one instance of a given MAC address. If (1) you connect the two types of switches through multiple ports or trunks belonging to different VLANs, and (2) enable routing on the switch having the multiple forwarding database; then, on the switch having the single forwarding database, the port and VLAN record it maintains for the connected multiple- forwarding-database switch can frequently change. This causes poor performance and the appearance of an intermittent or broken connection.

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