HP bh5700 User Manual page 68

index of the list element (numbering from 0) and q is the value specified by that element. So, this
example would read:
Priority 0 maps to Queue 1
Priority 1 maps to Queue 2
Priority 2 maps to Queue 2
Priority 3 maps to Queue 2
Priority 4 maps to Queue 3
Note that the tc priority map applies to a 4-bit field. With the Ethernet Switch Blade, the
priority map refers to the 802.1p tag, which is a 3-bit field. When translating this tc rule to
hardware, only Priorities 0 through 7 are significant; the other eight priorities are ignored.
The parameters wrr 1 2 4 6 specify that WRR scheduling is being used and assigns a relative
weight to each queue. The weights are treated as numbers of packets to be sent from each queue.
In this example, if the queues have sufficient packets, queue 1 will have twice as many packets
sent as queue 0, queue 2 will have four times as many, and queue 3 will have six times as many.
wrr parameters are scaled such that the maximum value is no more than 15. values which would
be 0 are set to 1:
Queue 0 has a weight of 1000 bytes
Queue 1 has a weight of 2000 bytes
Queue 2 has a weight of 4000 bytes
Queue 3 has a weight of 6000 bytes
The remaining commands each define a packet-limited FIFO queue. As with all previous tc
examples, these queues are created on device zhp0. However, unlike all previous examples,
they are not created as root disciplines for the device. Instead, the "parent" option identifies them
as child queues of the prio discipline.
For example, "parent 100:1" identifies that queue as the first child of the prio discipline (Queue
0), because the prio discipline's handle is 100:0.
After running each of those commands, again examine the CoS parameters. As with the simple
FIFO example, queue sizes change to 32 packets. In addition, though, the number of queues
changes to 4 for each port in zhp0. Furthermore, the weights have changed for each queue, as
have the queue mappings.
To test the strict priority case, simply remove the wrr 1 2 4 6 options from the first tc
command. Note that all queue disciplines in this test may be cleared by deleting the root
discipline, as before:
tc qdisc del dev zhp0 root
Ethernet Switch Blade User's Guide release 3.2.2j page 68
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