3Com WX3000 operation manual Trusting the 802.1p precedence, Trusting the Dscp precedence

The device does not support marking drop precedence for packets.

A device can operate in one of the following two priority trust modes when assigning precedence to received packets:

z

z

Packet priority trusted mode Port priority trusted mode

In terms of priority trust mode, the priority mapping process is shown in Figure 1-4.

Figure 1-4Assigning precedence to received packets in different trust modes

N

Trust port priority

Packet

Receiving port

Y

Look up the priority mapping table based on the packet priority to assign priority parameters (including local precedence and drop precedence) for the packet

Assign the port priority of the receiving port to the 802.1p precedence of the packet and look up the priority mapping table based on the packet priority to assign priority parameters (including local precedence and drop precedence) for the packet

As for packet priority trusted mode, you can configure to trust the following packet priority:

z

z

802.1p precedence DSCP precedence

Trusting the 802.1p precedence

In this mode, you can specify to process the received packets in one of the following two ways.

z

z

Keeping the original packet precedence unchanged (the default mode)

Replacing the original packet precedence with the corresponding one (the automap mode).

If a packet does not carry 802.1p precedence, the device uses the priority of the receiving port as the 802.1p precedence of the packet and then looks up the COS-precedence-to-other-precedence mapping table for the corresponding precedence.

Trusting the DSCP precedence

In this mode, you can specify to process the received packets in one of the following ways.

z

z

z

Keeping the original packet precedence unchanged (the default mode)

Replacing the original packet precedence with the corresponding one (the automap mode) Looking up the DSCP-precedence-to-DSCP-precedence mapping table for the local DSCP precedence and then looking up the DSCP-precedence-to-other-precedence mapping table based on the new DSCP precedence for the one to be assigned to the packets (the remap mode)

1-6