Static Virtual LANs (VLANs)

VLAN Operating Rules

protocol VLAN that does not already include the ARP VLAN protocol, the switch displays this message:

Indicates a protocol VLAN configured with IPv4, but not ARP.

Deleting Static VLANs: On the switches covered in this guide you can delete a VLAN regardless of whether there are currently any ports belonging to that VLAN. (The ports are moved to the default VLAN.)

Adding or Deleting VLANs: Changing the number of VLANs supported on the switch requires a reboot. (From the CLI, you must perform a write memory command before rebooting.) Other VLAN configuration changes are dynamic.

Inbound Tagged Packets: If a tagged packet arrives on a port that is not

atagged member of the VLAN indicated by the packet’s VID, the switch drops the packet. Similarly, the switch will drop an inbound, tagged packet if the receiving port is an untagged member of the VLAN indicated by the packet’s VID.

Untagged Packet Forwarding: To enable an inbound port to forward an untagged packet, the port must be an untagged member of either a protocol VLAN matching the packet’s protocol or an untagged member of

aport-based VLAN. That is, when a port receives an incoming, untagged packet, it processes the packet according to the following ordered crite- ria:

a.If the port has no untagged VLAN memberships, the switch drops the packet.

b.If the port has an untagged VLAN membership in a protocol VLAN that matches the protocol type of the incoming packet, then the switch forwards the packet on that VLAN.

c.If the port is a member of an untagged, port-based VLAN, the switch forwards the packet to that VLAN. Otherwise, the switch drops the packet.

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