Configuration Guide User guide

FastIron Configuration Guide 1983
53-1002494-02
Configuring QoS mapping configuration
Default DSCP to internal forwarding priority mappings
The DSCP values are described in RFCs 2474 and 2475. Table 342 lists the default mappings of
DSCP values to internal forwarding priority values.
Notice that DSCP values range from 0 through 63, whereas the internal forwarding priority values
range from 0 through 7. Any DSCP value within a given range is mapped to the same internal
forwarding priority value. For example, any DSCP value from 8 through 15 maps to priority 1.
After performing this mapping, the device maps the internal forwarding priority value to one of the
hardware forwarding queues.
On FWS, FCX, and ICX devices, you can use QoS queue 1 for priority traffic, even when sFlow is
enabled on the port. This differs from the FastIron X Series devices, which support seven priorities
for user data instead of eight when sFlow is enabled. QoS queue 1 is reserved for sFlow and not
used by other packets. Any non-sFlow packets assigned to QoS queue 1 will be directed to QoS
queue 0. Note that the ICX 6430 does not support sFlow.
Table 343 lists the default mappings of internal forwarding priority values to the hardware
forwarding queues for the ICX 6430.
You can change the DSCP to internal forwarding mappings. You also can change the internal
forwarding priority to hardware forwarding queue mappings.
TABLE 342 Default DSCP to internal forwarding priority mappings
Internal forwarding priority DSCP value
0 (lowest priority queue) 0 – 7
18 – 15
2 16 – 23
3 24 – 31
4 32 – 39
5 40 – 47
6 48 – 55
7 (highest priority queue) 56 – 63
TABLE 343 Default mappings of internal forwarding priority values for the ICX 6430
Internal forwarding priority Forwarding queues
0 (lowest priority queue) qosp0
1 qosp0
2qosp1
3qosp1
4qosp1
5qosp2
6qosp2
7 (highest priority queue) qosp3