ZNYX bh5700, User Manual, Page: 114 / 359

queue 1 after the qdisc handle. So the highest priority queue in this example is 105:8.
NOTE: 16 values must be provided for the priomap list. This is a feature of the Linux
priority system, which uses 16 priority levels. The last eight values given will be ignored.
Weighted Round Robin Qdisc
A weighted round robin qdisc builds on the above definition by adding the list of weights which
determine the order of scheduling from the queues:
tc qdisc add dev zre5 handle 105: prio bands 8 priomap 0 1 2 3 4 5 6
7 0 0 0 0 0 0 0 0 wrr 1 1 4 2 3 3 3 3
The weights apply to the eight queues in order, with the lowest numbered queue being given the
first weight. The weights determine the relative number of packets which will be sent from each
queue. In this example, assuming each queue has the necessary packets, the order of transmission
by queue number is:
7 6 5 4 3 2 1 0 7 6 5 4 3 2 7 6 5 4 2 2
This pattern repeats as long as there are packets to be transmitted in the queues.
Although the weights can be any integer value, they will be scaled so that the largest value is 15
or less and the smallest is at least 1.
FIFO Queues (pfifo and bfifo disciplines)
The simplest configuration for
tc
involves no classes or filters, and only a single FIFO queue.
With
tc
, queue sizes may be specified in bytes or packets. The first example defines a packet-
limited FIFO. This example begins with only
tc
and then illustrates
tc
in conjunction with
zqosd
.
As a first step, confirm that no
tc
configuration is active on the switch, by listing any queue
disciplines:
tc qdisc ls
The command should return nothing. Now, add a single packet-limited FIFO queue to
zhp0
and
confirm that it has been installed to software:
tc qdisc add dev zhp0 handle 100:0 root pfifo limit 32
tc qdisc ls
The output should display the following,
qdisc pfifo 100: dev zhp0 limit 32p
The
tc
command is applied to a device, so
dev
zhp0
must be specified. Note that a VLAN, such
as
zhp0
, and a port, such as
zre0
, are each treated as devices. Breakdown of the options:
Ethernet Switch Blade User's Guide release 3.2.2j page 114