Creating an ingress decode policy map, Forcing or merging the priority of a packet – 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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Creating an Ingress decode policy map
4
•
To assist the device in the decoding process described in “stage 1” decode-map tables are
defined.
Stage 2
Determine if a priority value should be forced or merged
•
If a packet’s EtherType matches 8100 or the port’s EtherType, derive a priority value and drop
precedence by decoding the PCP value.
•
If the qos pcp force command is configured on the port, the priority and drop precedence
values are set to the value read from the PCP bits.
•
If the qos exp force command is configured on the port, the priority and drop precedence
values are set to the value read from the MPLS EXP bits.
•
If the qos dscp force command is configured on the port, the priority and drop precedence
values are set to the value read from the DSCP bits.
•
If none of the qos force commands are configured, the priority and drop precedence values are
set for IPv4 or v6 packets and MPLS packets as described in the following:
For IPv4 or v6 Packets: Priority and drop precedence values obtained as a merge of the
decoded PCP and decoded DSCP values.
For MPLS Packets: Priority and drop precedence values obtained as a merge of the decoded
PCP and decoded EXP values.
Creating an Ingress decode policy map
Once a packet’s Ingress priority has been recognized for the PCP, DSCP and EXP values, those
values are matched against a policy map to determine the priority and drop precedence values that
will be assigned to the packet within the device. The maps used can be either:
•
Default policy maps described in
•
User-configured policy maps that are defined as described:
dscp decode-map decode-map-name – This command allows you to map a recognized DSCP
value to a value that you define.
pcp decode-map decode-map-name – This command allows you to map a recognized PCP
value to a value that you define.
exp decode-map decode-map-name – This command allows you to map a recognized MPLS
EXP value to a value that you define.
Forcing or merging 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.