Huawei quidway s7700 - Priority Mapping

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l EXP priority in MPLS packets

l SYN Flag field in Transmission Control Protocol (TCP) packets

l Source MAC address

l Destination MAC address

l Protocol type field encapsulated in Layer 2 packets

l Layer 3 protocol type

l ACL

l Discarded packets

You can dynamically add, modify, or delete the matching rules of a traffic classifier on the

S7700.

Priority Mapping

Different packets carry different precedence fields. For example, VLAN packets carry the 802.1p

field, IP packets carry the DSCP field or IP precedence, and MPLS packets carry the EXP

field. The mappings between priority fields must be configured on gateways to retain priorities

of packets when the packets traverse different networks.

To ensure QoS for different packets, when packets reach the S7700, the S7700 maps priorities

in packets or the default 802.1p priority of an interface to local priorities. The S7700 then

determines the queues that packets enter based on the mappings between internal priorities and

queues and performs traffic shaping, congestion avoidance, and queue scheduling. In addition,

the S7700 can re-mark priorities of outgoing packets so that the downstream device can provide

differentiated QoS based on packet priorities.

Table 1-1 and Table 1-2 show the mappings between internal priorities and queues.

Table 1-1 Mappings between internal priorities and queues on the X40SFC

Internal Priority

Queue Index

BE (unknown unicast packets, broadcast