5

Does a switch learns hosts mac address in these following scenarios:

  • Switch port configured as access and frames received tagged on different VLAN
  • Switch port configured as trunk and frames received tagged on non authorized trunk VLAN
  • Switch port configured as trunk without native VLAN and frames received not tagged
  • Switch port not configured (default), and frames received

And more global question, are these generals rules or does it depends of the vendors ?

10

It depends on the manufacturer. For Cisco switches:

Switch port configured as access and frames received tagged on different VLAN

Frame is dropped

Switch port configured as trunk and frames received tagged on non authorized trunk VLAN

Frame is dropped

Switch port configured as trunk without native VLAN and frames received not tagged

Frame is dropped

Switch port not configured (default), and frames received

The default configuration is access port on VLAN 1, so frame will be accepted and the switch will learn the MAC address.

  • Thanks. You confirm there are systematically no mac address learning in case of frames dropping ? – bdes31 Feb 28 at 14:59
  • @bdes31 When ingress frames are dropped due to an unauthorized VLAN ID, no MAC address is learned from them. Since the port isn't part of the VLAN anyway it wouldn't make sense to learn the MAC but not forward frames there. – Zac67 Feb 28 at 15:35

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