Brocade Multi-Service IronWare QoS and Traffic Management Configuration Guide (Supporting R05.6.00) - Manual (Page 122)

108 Multi-Service IronWare QoS and Traffic Management Configuration Guide
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Configuring QoS
4
The semantics and structure of the S-TAG is identical to that of the C-TAG, with the exception that bit
5 in octet 1, the Drop Eligible Indicator (DEI) bit, dis used to indicate if the packet is drop eligible.
This allows all 3 bits in the PCP ID to be used for indicating priority of the packet with the drop
precedence indicated by the DEI bit. The IEEE 802.1ad requires that if this capability is provided, it
must be independently manageable for each port.
On the Brocade device the qos use-dei command can be configured at the port level to allow a
drop-precedence value for incoming packet to be computed based on the DEI bit. Additionally, if
this command is configured, then a drop-eligible parameter will be encoded in the DEI bit of
transmitted frames. If the internal drop precedence of the packet is 2 or 3, the DEI will be
transmitted as 1; otherwise it will be transmitted as 0.
This command is configured as described in the following.
Brocade(config)# interface ethernet 10/1
Brocade(config-if-e10000-10/1)qos use-dei
Syntax: [no] qos use-dei
NOTE
This command applies for both Ingress and Egress processing.
Specifying the trust level and enabling marking
The following commands were retained from pre-03-8.00 versions of Multi-Service IronWare
software:
• qos-tos trust
• qos-tos mark
These commands operate on the QoS values within the packets as they arrive on the device. The
qos-tos trust command specifies which value among the following to use to classify the packet for
marking: cos, ip-prec, and dscp. The qos-tos mark command specifies a CoS or DSCP value to mark
on outgoing packets as specified by the mappings described in
“Packet mapping commands” on
page 110.
NOTES: You cannot use these commands and other L4 features such as:
• IPv4 ACLs and IPv4 ACL-based rate-limiting
• L2 ACLs and L2 ACL-based rate-limiting
• PBR
• VLAN ID and Inner VLAN ID translation on the same interface
NOTE
The design of this feature requires that the qos-tos trust and qos-tos mark commands be used
together.