Brocade Network OS Administrator’s Guide v4.1.1 - Manual (Page 393)

Service and transport VF classification with native VLANs
This section addresses two ways to classify service and transport VFs with native VLANs: a default
native VLAN mode, and a nondefault native VLAN mode.
Default-native-VLAN trunk mode
When a port is configured in normal trunk mode, a default native VLAN exists. Consequently, the native
VLAN complies with the existing native VLAN configuration and forwarding behavior in this mode. The
normal behavior for the existing native VLAN is as follows:
• Default native VLAN 1 exists when the port first enters this mode.
• The default native VLAN always exists (either as VLAN 1 or any 802.1Q VLAN ID) and cannot be
deleted.
• A tagged native VLAN is always forwarded and cannot be discarded, unless it is blocked by STP.
• Egress tagging behavior depends on acceptable ingress frame types:
‐ Tagged egress is enabled only if the acceptable ingress frame type is tagged only.
‐ Untagged egress is enabled only if the acceptable ingress frame type includes untagged
frames.
‐ Egress tagging cannot preserve ingress frame encapsulation.
The following commands are applicable to native VLANs (802.1Q VLANs or service VFs):
• [no] switchport trunk native vlan vid [ctag ctag]
• [no] dot1q tag native (global configuration mode)
• [no] switchport trunk tag native-vlan (interface subtype configuration mode)
The first command is used to define a native 802.1Q VLAN or a native service or transport VF. The last
two commands are used to control the ingress acceptable frame and egress tagged behavior. The
802.1Q native VLAN classifications and the role of the respective commands are summarized below.
802.1Q native VLAN classifications TABLE 63
Ingress allowed frame type Egress
tagging:
Untagged
only Egress
tagging:
Tagged only CLI commands
None N/A N/A None (tagged 802.1Q native VLAN is always
forwarded)
Untagged only No N/A
None (tagged 802.1Q native VLAN is always
forwarded)
Tagged only N/A Yes switchport trunk native vlan vid,
switchport trunk tag native-vlan,
AND dot1q tag native
Untagged and tagged Yes No switchport trunk native vlan vid,
no switchport trunk tag native-vlan,
OR no dot1q tag native
The service VF classification rules are similar to those for native VLAN classification, but with the
following exceptions:
Service and transport VF classification with native VLANs
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