Preserving 802.1Q Vlan Tag Value For Lite Subinterfaces - Dell Z9500 Configuration Manual

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To provide lossless service for RRoCE, the QoS service policy must be configured in the ingress and egress directions on lite

sub interfaces.

Preserving 802.1Q VLAN Tag Value for Lite

Subinterfaces

This functionality is supported on the platform.

All the frames in a Layer 2 VLAN are identified using a tag defined in the IEEE 802.1Q standard to determine the VLAN to which

the frames or traffic are relevant or associated. Such frames are encapsulated with the 802.1Q tags. If a single VLAN is

configured in a network topology, all the traffic packets contain the same do1q tag, which is the tag value of the 802.1Q

header. If a VLAN is split into multiple, different sub-VLANs, each VLAN is denoted by a unique 8021.Q tag to enable the nodes

that receive the traffic frames determine the VLAN for which the frames are destined.

Typically, a Layer 3 physical interface processes only untagged or priority-tagged packets. Tagged packets that are received on

Layer 3 physical interfaces are dropped. To enable the routing of tagged packets, the port that receives such tagged packets

needs to be configured as a switchport and must be bound to a VLAN as a tagged member port.

A lite subinterface is similar to a normal Layer 3 physical interface, except that additional provisioning is performed to set the

VLAN ID for encapsulation.

A physical interface or a Layer 3 Port channel interface can be configured as a lite subinterface. Once a lite subinterface is

configured, only tagged IP packets with encapsulation VLAN ID are processed and routed. All other data packets are discarded

except the Layer 2 and Layer 3 control frames. It is not required for a VLAN ID to be preserved (in the hardware or the OS

application) when a VLAN ID, used for encapsulation, is associated with a physical/Port-channel interface. Normal VLANs and

VLAN encapsulation can exist simultaneously and any non-unicast traffic received on a normal VLAN is not flooded using lite

subinterfaces whose encapsulation VLAN ID matches with that of the normal VLAN ID.

You can use the encapsulation dot1q vlan-id command in INTERFACE mode to configure lite subinterfaces.

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