Administrator Guide

Table Of Contents
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.
Flex Hash and Optimized Boot-Up
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