enabled, the packets comprise TCP and UDP packets and they can be marked with DSCP code points. Multicast is not supported in thatnetwork.RRoCE packets are received and transmitted on specific interfaces called lite-subinterfaces. These interfaces are similar to the normalLayer 3 physical interfaces except for the extra provisioning that they offer to enable the VLAN ID for encapsulation.You can configure a physical interface or a Layer 3 Port Channel interface as a lite subinterface. When you configure a lite subinterface, onlytagged IP packets with VLAN encapsulation are processed and routed. All other data packets are discarded.A normal Layer 3 physical interface processes only untagged packets and makes routing decisions based on the default Layer 3 VLAN ID(4095).To enable routing of RRoCE packets, the VLAN ID is mapped to the default VLAN ID of 4095 using VLAN translation. After the VLANtranslation, the RRoCE packets are processed in the same way as normal IP packets that a Layer 3 interface receives and routes in theegress direction. At the egress interface, the VLAN ID is appended to the packet and transmitted out of the interface as a tagged packetwith the dot1Q value preserved.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 LiteSubinterfacesThis 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 framesor traffic are relevant or associated. Such frames are encapsulated with the 802.1Q tags. If a single VLAN is configured in a networktopology, 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 theVLAN 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 3physical interfaces are dropped. To enable the routing of tagged packets, the port that receives such tagged packets needs to beconfigured 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 forencapsulation.A physical interface or a Layer 3 Port channel interface can be configured as a lite subinterface. Once a lite subinterface is configured, onlytagged IP packets with encapsulation VLAN ID are processed and routed. All other data packets are discarded except the Layer 2 and Layer3 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 forencapsulation, is associated with a physical/Port-channel interface. Normal VLANs and VLAN encapsulation can exist simultaneously andany non-unicast traffic received on a normal VLAN is not flooded using lite subinterfaces whose encapsulation VLAN ID matches with thatof 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 343
