Brocade Multi-Service IronWare QoS and Traffic Management Configuration Guide (Supporting R05.6.00) - Manual (Page 89)

Multi-Service IronWare QoS and Traffic Management Configuration Guide 75
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Forcing or merging the drop precedence of a packet
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• Forced to a priority configured for a specific VLAN. The priority force command is configured at
the VLAN where you want is to be applied.
• Forced to a priority that is obtained from the DSCP priority bits. The qos- dscp force command
is configured at the interface where you want it to be applied.
• Forced to a priority that is obtained from the EXP priority bits. The qos- exp force command is
configured at the interface where you want it to be applied.
• Forced to a priority that is obtained from the PCP priority bits. The qos- pcp force command is
configured at the interface where you want it to be applied.
• Forced to a priority that is based on an ACL match. The priority-force keyword can be used
within an ACL to apply a priority to specified traffic.
If multiple commands containing the priority force keyword are specified, the command with the
highest precedence will take effect as determined by the following order.
1. ACL match (if the qos-tos mark cos command is configured, it has the same #1 priority
precedence as ACL match). Refer to “Specifying the trust level and enabling marking” on
page 108 for details.
2. VLAN priority
NOTE
VLAN priority works differently for Layer 2 and Layer 3 traffic. If you apply VLAN priority to a
physical port for layer 2 traffic then it will apply VLAN priority and will change traffic accordingly.
However, if you apply VLAN priority to a physical port for layer 3 traffic then it will not apply and
will not change traffic. VLAN priority will only apply to layer 3 traffic if the port is a VE port.
3. Physical port priority value.
4. DSCP value in an incoming IPv4 or v6 packet.
5. EXP value in an incoming MPLS packet.
6. PCP value in a tagged frame or PCP field or .1ad DE
Details of how to configure the force commands are provided in “Configuring a force priority” on
page 96.
Forcing or merging the drop precedence of a packet
Once a packet’s Ingress drop precedence has been mapped, the values that will be used for
processing on the device are determined by either forcing or merging.
There are a variety of commands to “force” the drop precedence of a packet based on the following
criteria:
• Forced to a drop precedence configured for a specific Ingress port. The drop-precedence force
command is configured at the interface where you want it to be applied.
• Forced to a drop precedence that is obtained from the DSCP priority bits. The qos dscp force
command is configured at the interface where you want it to be applied.
• Forced to a drop precedence that is obtained from the EXP priority bits. The qos exp force
command is configured at the interface where you want it to be applied.
• Forced to a drop precedence that is obtained from the PCP priority bits. The qos pcp force
command is configured at the interface where you want it to be applied.