Administrator Guide

VLANs and Port Tagging
To add an interface to a VLAN, it must be in Layer 2 mode. After you place an interface in Layer 2 mode, it is automatically placed in
the default VLAN. Dell Networking OS supports IEEE 802.1Q tagging at the interface level to lter trac. When you enable tagging,
a tag header is added to the frame after the destination and source MAC addresses. The information that is preserved as the frame
moves through the network. The below gure shows the structure of a frame with a tag header. The VLAN ID is inserted in the tag
header.
Figure 15. Tagged Frame Format
The tag header contains some key information used by Dell Networking OS:
• The VLAN protocol identier identies the frame as tagged according to the IEEE 802.1Q specications (2 bytes).
• Tag control information (TCI) includes the VLAN ID (2 bytes total). The VLAN ID can have 4,096 values, but two are reserved.
NOTE: The insertion of the tag header into the Ethernet frame increases the size of the frame to more than the 1518
bytes specied in the IEEE 802.3 standard. Some devices that are not compliant with IEEE 802.3 may not support the
larger frame size.
Information contained in the tag header allows the system to prioritize trac and to forward information to ports associated with a
specic VLAN ID. Tagged interfaces can belong to multiple VLANs, while untagged interfaces can belong only to one VLAN.
Conguring VLAN Membership
By default, all Aggregator ports are member of all (4094) VLANs, including the default untagged VLAN 1. You can use the CLI or
CMC interface to recongure VLANs only on server-facing interfaces (1–32) so that an interface has membership only in specied
VLANs.
To assign an Aggregator interface in Layer 2 mode to a specied group of VLANs, use the vlan tagged and vlan untagged
commands. To view which interfaces are tagged or untagged and to which VLAN they belong, use the show vlan command
(Displaying VLAN Membership).
To recongure an interface as a member of only specied tagged VLANs, enter the vlan tagged command in INTERFACE mode:
Command Syntax
Command Mode Purpose
vlan tagged {vlan-id | vlan-range} INTERFACE Add the interface as a tagged member of one or more VLANs,
where:
vlan-id species a tagged VLAN number. Range: 2-4094
vlan-range species a range of tagged VLANs. Separate
VLAN IDs with a comma; specify a VLAN range with a dash;
for example, vlan tagged 3,5-7.
To recongure an interface as a member of only specied untagged VLANs, enter the vlan untagged command in INTERFACE
mode:
Interfaces
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