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DES-3500 Layer 2 Fast Ethernet Switch CLI Reference Manual
102
14
QOS COMMANDS
The DES-3500 switch supports 802.1p priority queuing. The Switch has 4 priority queues. These priority queues are numbered
from 3 (Class 3) — the highest priority queue — to 0 (Class 0) — the lowest priority queue. The eight priority tags specified in
IEEE 802.1p (p0 to p7) are mapped to the Switch’s priority queues as follows:
• Priority 0 is assigned to the Switch’s Q1 queue.
• Priority 1 is assigned to the Switch’s Q0 queue.
• Priority 2 is assigned to the Switch’s Q0 queue.
• Priority 3 is assigned to the Switch’s Q1 queue.
• Priority 4 is assigned to the Switch’s Q2 queue.
• Priority 5 is assigned to the Switch’s Q2 queue.
• Priority 6 is assigned to the Switch’s Q3 queue.
• Priority 7 is assigned to the Switch’s Q3 queue.
Priority scheduling is implemented by the priority queues stated above. The Switch will empty the four hardware priority queues
in order, beginning with the highest priority queue, 3, to the lowest priority queue, 0. Each hardware queue will transmit all of the
packets in its buffer before permitting the next lower priority to transmit its packets. When the lowest hardware priority queue has
finished transmitting all of its packets, the highest hardware priority queue will begin transmitting any packets it may have
received.
The commands in the Command Line Interface (CLI) are listed (along with the appropriate parameters) in the following table.
Command Parameters
config bandwidth_control [<portlist>] {rx_rate [no_limit | <value 1-1000>] | tx_rate
[no_limit <value 1-1000>]}
show bandwidth_control <portlist>
config scheduling <class_id 0-3> {max_packet <value 0-255> |
max_latency <value 0-255>}
show scheduling
config 802.1p user_priority <priority 0-7> <class_id 0-3>
show 802.1p user_priority
config 802.1p default_priority [<portlist> | all] <priority 0-7>
show 802.1p default_priority <portlist>
Each command is listed, in detail, in the following sections.
config bandwidth_control
Purpose Used to configure bandwidth control on a port by-port basis.
Syntax
config bandwidth_control [<portlist>] {rx_rate [no_limit | <value
1-1000>] | tx_rate [no_limit <value 1-1000>]}
Description
The config bandwidth_control command is used to configure
bandwidth on a port by-port basis.
Parameters
<portlist> − Specifies a port or range of ports to be configured.
rx_rate − Specifies that one of the parameters below (no_limit or
<value 1-1000>) will be applied to the rate at which the above
specified ports will be allowed to receive packets
no_limit − Specifies that there will be no limit on the rate of
packets received by the above specified ports.
<value 1-1000> − Specifies the packet limit, in Mbits, that the