4-2
z dscp-dscp: DSCP-to-DSCP priority mapping table, which is applicable to only IP packets.
z exp-dot1p: EXP-to-802.1p priority mapping table. (Available only on the EB and SD cards)
z exp-dp: EXP-to-drop priority mapping table.
The default priority mapping tables (as shown in
Appendix A Default Priority Mapping Tables) are
available for priority mapping. Generally, they are sufficient for priority mapping. If a default priority
mapping table cannot meet your requirements, you can modify the priority mapping table as required.
Priority Trust Mode on a Port
The priority trust mode on a port decides which priority is used for priority mapping table lookup. There
are two priority trust modes on the H3C S7500E series switches:
z dot1p: Uses the 802.1p priority carried in packets for priority mapping.
z dscp: Uses the DSCP carried in packets for priority mapping.
In addition, port priority was introduced for 802.1q untagged packets. Thus, when a port configured
with the 802.1p trust mode receives an 802.1q untagged packet, the priority of the port is used as the
802.1p priority of the packet for priority mapping table lookup.
The priority mapping procedure varies with the priority modes, as described in the next section
Priority
Mapping Procedure
.
Priority Mapping Procedure
Figure 4-1 presents how the S7500E performs priority mapping for an Ethernet packet. The procedure
differs depending on whether the packet is 802.1q tagged or not.
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