Quality of Service | 853Honor dot1p Priorities on Ingress TrafficBy default FTOS does not honor dot1p priorities on ingress traffic. Use the command service-classdynamic dot1p from INTERFACE mode to honor dot1p priorities on ingress traffic, as shown inFigure 41-3. You can configure this feature on physical interfaces and port-channels, but you cannotconfigure it on individual interfaces in a port channel.On the C-Series and S-Series you can configure service-class dynamic dot1p from CONFIGURATIONmode, which applies the configuration to all interfaces. A CONFIGURATION mode service-class dynamicdot1p entry supersedes any INTERFACE entries. See Mapping dot1p values to service queues onpage 867.Figure 41-3. service-class dynamic dot1p Command ExamplePriority-tagged Frames on the Default VLANPriority-tagged Frames on the Default VLAN is available only on platforms: ex c sPriority-tagged frames are 802.1Q tagged frames with VLAN ID 0. For VLAN classification these packetsare treated as untagged. However, the dot1p value is still honored when service-class dynamic dot1p ortrust dot1p is configured.When priority-tagged frames ingress an untagged port or hybrid port the frames are classified to the defaultVLAN of the port, and to a queue according to their dot1p priority if service-class dynamic dotp or trustdot1p are configured. When priority-tagged frames ingress a tagged port, the frames are dropped becausefor a tagged port the default VLAN is 0.Note: You cannot configure service-policy input and service-class dynamic dot1p on the same interface.FTOS Behavior: Hybrid ports can receive untagged, tagged, and priority tagged frames. The ratemetering calculation might be inaccurate for untagged ports, since an internal assumption is made thatall frames are treated as tagged. Internally the ASIC adds a 4-bytes tag to received untagged frames.Though these 4-bytes are not part of the untagged frame received on the wire, they are included in therate metering calculation resulting in metering inaccuracy.FTOS#config tFTOS(conf)#interface gigabitethernet 1/0FTOS(conf-if)#service-class dynamic dot1pFTOS(conf-if)#endFTOS#
