Dell PowerConnect B-RX Configuration Manual page 554

18
Classification
FIGURE 87
As shown in the figure, the first criteria considered are port-based, MAC-based, and port-based
VLAN classifications. The packet is primarily classified with the higher of these two criteria. Next,
the packet is classified based on the trust level set. If there is no trust level set, the packet retains
the port or MAC derived QoS classification, If a trust level is set, the packet will either take the
802.1p or DSCP priority depending on which is set as the trust level.
Once a packet is classified by one of the procedures mentioned, it is mapped to an internal
forwarding queue in the BigIron RX. There are four queues designated as 0 to 3. The internal
forwarding priority maps to one of these four queues as shown in
mapping between the internal priority and the forwarding queue cannot be changed.
Table 91
trust level for CoS or DSCP is enabled.
TABLE 91
DSCP value
802.1p (COS)
Value
DSCP value
Internal
Forwarding
Priority
Forwarding
Queue
478
Priority resolution
802.1p Priority
Trust Level
Set to COS
(default)
Port-based
Classification
through Table 94 show the default QoS mappings on the device, which are used if the
Default QoS mappings, columns 0 to 15
0 1 2 3
0 0 0 0
0 1 2 3
0 0 0 0
0 0 0 0
No
Trust Level
Set
Trust Level
Determine Set to DSCP
Trust Level
Set Classification to
Higher of both Inputs
MAC-based
Classification
Port-based VLAN
Classification
4 5 6 7 8
0 0 0 0 1
4 5 6 7 8
0 0 0 0 1
0 0 0 0 0
DSCP Priority
Table 91 through Table
9 10 11 12 12
1 1 1 1 1
9 10 11 12 12
1 1 1 1 1
0 0 0 0 0
BigIron RX Series Configuration Guide
53-1002253-01
94. The
14 15
1 1
14 15
1 1
0 0