Users Guide

the network. The following example shows the structure of a frame with a tag header. The VLAN ID is inserted in the tag
header.
Figure 121. Tagged Frame Format
The tag header contains some key information that Dell Networking OS uses:
• The VLAN protocol identifier identifies the frame as tagged according to the IEEE 802.1Q specifications (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 1,518 bytes
as specified 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 traffic and to forward information to ports associated
with a specific VLAN ID. Tagged interfaces can belong to multiple VLANs, while untagged interfaces can belong only to one
VLAN.
Configuration Task List
This section contains the following VLAN configuration tasks.
• Creating a Port-Based VLAN (mandatory)
• Assigning Interfaces to a VLAN (optional)
• Assigning an IP Address to a VLAN (optional)
• Enabling Null VLAN as the Default VLAN
Creating a Port-Based VLAN
To configure a port-based VLAN, create the VLAN and then add physical interfaces or port channel (LAG) interfaces to the
VLAN.
NOTE
: The Default VLAN (VLAN 1) is part of the system startup configuration and does not require configuration.
A VLAN is active only if the VLAN contains interfaces and those interfaces are operationally up. As shown in the following
example, VLAN 1 is inactive because it does not contain any interfaces. The other VLANs contain enabled interfaces and are
active.
NOTE
: In a VLAN, the shutdown command stops Layer 3 (routed) traffic only. Layer 2 traffic continues to pass through the
VLAN. If the VLAN is not a routed VLAN (that is, configured with an IP address), the shutdown command has no affect on
VLAN traffic.
When you delete a VLAN (using the no interface vlan vlan-id command), any interfaces assigned to that VLAN are
assigned to the Default VLAN as untagged interfaces.
To create a port-based VLAN, use the following command.
• Configure a port-based VLAN (if the VLAN-ID is different from the Default VLAN ID) and enter INTERFACE VLAN mode.
CONFIGURATION mode
interface vlan vlan-id
To activate the VLAN, after you create a VLAN, assign interfaces in Layer 2 mode to the VLAN.
Virtual LANs (VLANs) 848