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Configuring VLANs 649
trunk port are forwarded on the native VLAN. Packets received on another
interface belonging to the native VLAN are transmitted untagged on a
trunk port.
• General — General ports can act like access or trunk ports or a hybrid of
both.
VLAN membership rules that apply to a port are based on the switchport
mode configured for the port. Table 21-2 shows the behavior of the three
switchport modes.
When a port is in General mode, all VLAN features are configurable. When
ingress filtering is on, the frame is dropped if the port is not a member of the
VLAN identified by the VLAN ID in the tag. If ingress filtering is off, all
tagged frames are forwarded. The port decides whether to forward or drop the
frame when the port receives the frame.
VLAN Tagging
Dell Networking series switches support IEEE 802.1Q tagging. Ethernet
frames on a tagged VLAN have a 4-byte VLAN tag in the header. VLAN
tagging is required when a VLAN spans multiple switches, which is why trunk
ports transmit and receive only tagged frames.
Table 21-2. Switchport Mode Behavior
Mode VLAN Membership Frames
Accepted
Frames Sent Ingress
Filtering
Access One VLAN Untagged/
Tagged
Untagged Always On
Trunk All VLANs that exist in
the system (default)
Untagged/
Tagged
Tagged an d
Untagged
Always On
General As many as desired Tagged or
Untagged
Tagged or
Untagged
On or Off
NOTE: A stack of switches behaves as a single switch, so VLAN tagging is not
required for packets traversing different stack members.