Forcing the priority of a packet, Acl qos considerations – Brocade Multi-Service IronWare QoS and Traffic Management Configuration Guide (Supporting R05.6.00) User Manual
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Multi-Service IronWare QoS and Traffic Management Configuration Guide
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Forcing the priority of a packet
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Forcing the priority of a packet
Once a packet’s ingress priority 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 priority of a packet based on the following criteria:
•
Forced to a priority configured for a specific ingress port. The priority force command is
configured at the interface where you want it 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 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.
NOTE
Commands to “force” the priority of a packet are not supported for the vlan priority command in the
Brocade NetIron CES and Brocade NetIron CER platforms.
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
2. Physical port priority value
3. DSCP value in an incoming IPv4 packet
4. PCP value in a tagged frame or PCP
Details of how to configure the force commands are provided in
“Configuring a force priority”
ACL QoS Considerations
The following should be considered when configuring QoS.
•
All packets with ACL match where action is Priority/Priority force will have BOTH UP and EXP bit
encoded.
•
Regardless of the Port Encoding settings.The effect will be user visible only if the outgoing
packet is MPLS for non-MPLS, packets the functionality will remain same as before.
•
The EXP bit is carried to the Remote VPLS/VLL in the inner label (VC Label). QoS assignment is
on the remote.
•
PE device will be based on this EXP. The outgoing packet's PCP value will be encoded based on
QoS assigned by the EXP.
•
At Ingress:
•
ACL-->TC Assignment ---> TC Encodes {UP, EXP}
•
At Remote VPLS:
•
EXP Based QoS Assignment-->TC--> TC Encodes {UP}