Vlan Tagging - Dell PowerConnect 7048P Manual

Powerconnect 7000 series stackable layer 2 and 3 switches

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Table 21-2. Switchport Mode Behavior

VLAN Membership

All VLANs that exist

in the system

As many as desired

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

PowerConnect 7000 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.

A stack of switches behaves as a single switch, so VLAN tagging is not

required for packets traversing different stack members.

Tagging may be required when a single port supports multiple devices that are

members of different VLANs. For example, a single port might be connected

to an IP phone, a PC, and a printer (the PC and printer are connected via

ports on the IP phone). IP phones are typically configured to use a tagged

VLAN for voice traffic, while the PC and printers typically use the untagged

When a port is added to a VLAN as an untagged member, untagged packets

entering the switch are tagged with the PVID (also called the

of the port. If the port is added to a VLAN as an untagged member, the port

does not add a tag to a packet in that VLAN when it exits the port.

Configuring VLANs