Licensing Requirements and Limitations for Priority Mapping (CE12800)

Involved Network Elements

Other network elements are not required.

Licensing Requirements

Priority mapping is a basic feature of a switch and is not under license control.

Version Requirements

For details about the mapping between software versions and switch models, see the Hardware Query Tool.

Software version evolution: V100R001C00 -> V100R002C00 -> V100R003C00 -> V100R003C10 -> V100R005C00 -> V100R005C10 -> V100R006C00 -> V200R001C00 -> V200R002C50 -> V200R003C00 -> V200R005C00 -> V200R005C10 -> V200R019C00 -> V200R019C10

Feature Limitations

Default Trusted Priority

• Layer 3 physical interfaces and VLANIF interfaces trust DSCP priorities. This cannot be modified.

• On an MPLS network, MPLS EXP priorities are trusted. This cannot be modified.

• By default, the inbound interface trusts 802.1p priorities of multicast packets that are forwarded based on MAC addresses, and trusts DSCP priorities of multicast packets that are forwarded based on IP addresses.

• By default, Layer 2 packets are processed based on the mapping of 802.1p priorities, and Layer 3 packets are processed based on the mapping of DSCP priorities.

Limitations on Priority Mapping

• The default DiffServ domain is default. In addition to this domain, the device supports a maximum of six DiffServ domains. You can change the mapping in the DiffServ domain default, but cannot delete the domain.
• Starting from V100R003C10, if the mapping between PHBs and DSCP priorities is configured in the outbound direction of a VLAN, a maximum of three DiffServ domains (including the DiffServ domain default) can be applied to all VLANs on the device. The same DiffServ domain can be applied to different VLANs.
• Colors are used to determine whether the packets are discarded during congestion avoidance and are independent of the mapping between internal priorities and queues.
• When a DiffServ domain is applied to a MUX VLAN or super-VLAN, the device can only map inbound Layer 3 traffic based on 802.1p priorities in the DiffServ domain.
• In the VLAN view, only the following models support mapping between PHBs and DSCP priorities: CE-L48GT-ED, CE-L48GS-ED, CE-L12XS-ED, CE-L24XS-EC, CE-L24XS-ED, CE-L48XS-EC, CE-L48XS-ED, CE-L48XS-EF, CE-L06LQ-EC, CE-L02LQ-EC, CE-L12LQ-EF, CE-L24LQ-EC, CE-L04CF-EF, and CE-L04CF-EC.
• If the mapping from PHBs to DSCP priorities is enabled on the outbound interface, bits 6 and 7 in the ToS field of IPv6 packets are mapped to 0. The device does not support ECN for IPv6 packets or IPv6 over MPLS packets.
• The VXLAN decapsulation device maps PHBs of Layer 3 packets to DSCP priorities based on the mapping between inner DSCP fields of VXLAN packets and the mapping template of the VBDIF interface. To modify the outer DSCP field of VXLAN packets, configure a traffic policy containing DSCP priority re-marking on the device in the inbound direction.
• In non-enhanced mode, when a QoS group containing VLANs or VLANIF interfaces is configured, mapping between PHBs and DSCP priorities in the outbound direction of the VLAN cannot be configured. Similarly, if mapping between PHBs and DSCP priorities in the outbound direction of a VLAN is configured, a QoS group containing VLANs or VLANIF interfaces cannot be configured.

• In V200R003C00 versions, when a switch with the CE-L48XS-FG, CE-L36CQ-FG, CE-L36CQ-FD1, CE-L36CQ-SD, CE-L48XS-FD1, CE-L08CF-FG1, or CE-L16CQ-FD card is configured as a Layer 3 VXLAN gateway and performs VXLAN encapsulation, the DSCP priority in the outer IP header of a VXLAN packet is incorrectly mapped and differs from the DSCP priority in the inner IP header. It is recommended that you do not configure a switch with such cards as a Layer 3 VXLAN gateway.

• On a TRILL network, priority mapping can be performed based only on 802.1p priorities.
  • On an ingress node, the internal priority is mapped based on the 802.1p priority and DiffServ domain of the CE VLAN in the inbound direction. The 802.1p priority of the outer carrier VLAN is mapped based on the internal priority and DiffServ domain of the CE VLAN in the outbound direction.
  • On a transit node, the internal priority is mapped based on the 802.1p priority and DiffServ domain of the carrier VLAN in the inbound direction. The 802.1p priority of the outer carrier VLAN is mapped based on the internal priority and DiffServ domain of the carrier VLAN in the outbound direction.
  • On an egress node, the internal priority is mapped based on the 802.1p priority and DiffServ domain of the carrier VLAN in the inbound direction. The 802.1p priority of the inner CE VLAN is mapped based on the internal priority and DiffServ domain of the carrier VLAN in the outbound direction.

Limitations on Interface Priority

• The priority of a Layer 3 physical interface is 0 and cannot be configured.
• When an interface is added to a VLAN and the trusted priority is configured on the interface and in the VLAN, the trusted priority on the interface takes effect.
• The priority cannot be configured for Eth-Trunk member interfaces.

Limitations When Priority Mapping Is Used with Other Services

• You can create a DiffServ domain, enable the mapping between PHBs and DSCP/802.1p priorities in the outbound direction, and configure the mapping between CoS values and queue indexes only in the Admin-VS in port mode. The configurations take effect for other VSs in port mode.

• You can create a DiffServ domain, enable the mapping between PHBs and DSCP/802.1p priorities in the outbound direction, and configure the mapping between CoS values and queue indexes in all VSs in group mode. The configurations take effect for the local VS.

• When FCF or NPV is configured, the mapping from PHBs to 802.1p priorities in the outbound direction cannot be disabled. Otherwise, the device cannot send backpressure signals.

Priority Mapping in Different Forwarding Scenarios

When processing QoS services, the device maps external priorities (such as 802.1p or DSCP values) of packets to internal priorities (PHBs and packet colors) in the inbound direction of an interface, and maps internal priorities to external priorities in the outbound direction. Priority mapping is implemented by configuring different priority mapping relationships through DiffServ domains. In this way, differentiated QoS services are provided.

• The following table lists the default priority mapping behaviors for packets forwarded through different interfaces in non-VXLAN scenarios.

  Table 3-2 Default priority mapping behaviors for Layer 2 and Layer 3 forwarding

  Forwarding Scenario	Inbound Direction	DSCP Value of Outgoing Packets	802.1p Value of Outgoing Packets
  Layer 2 forwarding: VLAN-based forwarding	By default, the device maps the 802.1p value in a packet to the internal priority based on the DiffServ domain configured in the VLAN.	If a packet contains a DSCP value, the DSCP value is not modified by default when the packet is routed out of the VLAN.	The internal priority in a packet is mapped to an 802.1p value based on the DiffServ domain configured in the VLAN.
  Layer 3 forwarding: forwarding through Layer 3 interfaces	By default, the device maps the DSCP value in a packet to the internal priority based on the DiffServ domain configured on the Layer 3 interface.	The DSCP value in packets is mapped from the internal DSCP value of the device. The internal DSCP value of the device can be modified using the ip-dscp-inbound map in-dscp and ip-dscp-outbound in-dscp map commands. If the qos phb marking dscp enable command is configured, the DSCP value in packets is mapped from the internal priority based on the DiffServ domain configured on the Layer 3 interface.	N/A
  Layer 3 forwarding: forwarding through VLANIF interfaces	By default, the device maps the DSCP value in a packet to the internal priority based on the DiffServ domain configured on the VLANIF interface.	The DSCP value in packets is mapped from the internal DSCP value of the device. The internal DSCP value of the device can be modified using the ip-dscp-inbound map in-dscp and ip-dscp-outbound in-dscp map commands. If the qos phb marking dscp enable command is configured, the DSCP value in packets is mapped from the internal priority based on the DiffServ domain configured on the VLANIF interface.	The 802.1p value in packets is mapped from the internal priority based on the DiffServ domain configured on the VLANIF interface.

• The default priority mapping behaviors for packets forwarded through VXLAN tunnels in VXLAN scenarios are as follows:

  1. After an original packet arrives at a Layer 2 sub-interface on the switch, the switch maps the 802.1p or DSCP value of the original packet to the internal priority (PHB and color) based on the DiffServ domain applied to the Layer 2 sub-interface, and then sends the packet to a specified queue.

  2. The switch encapsulates the packet into a VXLAN packet and forwards it to the VXLAN tunnel. The following table describes the QoS priorities of the encapsulated packet.

     Device Model	802.1p Value of the Encapsulated Packet	DSCP Value of the Encapsulated Packet
     CE12800	By default, the outer 802.1p value of the encapsulated packet is mapped from the internal priority, and the inner 802.1p value of the encapsulated packet remains unchanged. After the qos phb marking 8021p disable command is configured in the system view, the outer 802.1p value is 2, and the inner 802.1p value remains unchanged.	For a VXLAN-encapsulated packet forwarded at Layer 3: By default, the outer DSCP value of the encapsulated packet is mapped from the internal priority, and the inner DSCP value of the encapsulated packet is mapped from the internal DSCP value on the switch. After the qos phb marking dscp enable command is configured in the system view, both the outer and inner DSCP values are mapped from the internal priority. For a VXLAN-encapsulated packet forwarded at Layer 2: By default, the outer DSCP value of the encapsulated packet is mapped from the internal priority, and the inner DSCP value of the encapsulated packet remains unchanged. After the qos phb marking dscp enable command is configured in the system view, the preceding mappings are not changed.
     CE12800E (configured with ED-E, EG-E, and EGA-E series cards)	By default, the outer 802.1p value of the encapsulated packet is mapped from the internal priority, and the inner 802.1p value of the encapsulated packet remains unchanged. After the qos phb marking 8021p disable command is configured in the Ethernet interface view, the outer 802.1p value is the same as the internal priority, and the inner 802.1p value remains unchanged.	By default, the outer DSCP value of the encapsulated packet is 0, and the inner DSCP value of the encapsulated packet remains unchanged. After the qos phb marking dscp enable command is configured in the Ethernet interface view, the outer DSCP value is mapped from the internal priority, and the inner DSCP value remains unchanged.
     CE12800E (configured with FD-X series cards)	By default, the outer 802.1p value of the encapsulated packet is mapped from the internal priority, and the inner 802.1p value of the encapsulated packet remains unchanged. After the qos phb marking 8021p disable command is configured in the Ethernet interface view, the preceding mappings are not changed.	By default, the outer DSCP value of the encapsulated packet is mapped from the internal priority, and the inner DSCP value of the encapsulated packet remains unchanged. After the qos phb marking dscp enable command is configured in the Ethernet interface view, the preceding mappings are not changed. After the qos phb marking dscp disable command is configured in the NVE interface view, the outer DSCP value is the same as the DSCP value of the original packet, and the inner DSCP value remains unchanged.

  3. When the packet leaves the tunnel, its 802.1p or DSCP value (depending on which value is trusted on the tunnel interface) is mapped to the internal priority based on the configured DiffServ domain (based on only the default DiffServ domain for the CE12800). The packet then enters the queue matching the internal priority. An Ethernet interface working in Layer 3 mode only trusts the DSCP value.

  4. The internal priority is mapped based on the DiffServ domain applied to the Layer 2 sub-interface or physical outbound interface. The packet is then transmitted based on the mapped priority.