3Com Switch 7750 Configuration Guide

666 CHAPTER 61: QOS CONFIGURATION
■ When the queue length is bigger than the upper limit, all inbound packets all
dropped.
■ When the queue length is in the range of the upper limit and the lower limit,
the inbound packets are dropped at random. In this case, a number is assigned
to each inbound packet and then compared with the drop probability of the
current queue. If the number is bigger than the drop probability, the inbound
packet is dropped. The longer a queue is, the higher the drop probability is.
However, there is a top drop probability.
QoS Supported by the
Switch 7750
Setting Port Priority
If an inbound packet is not VLAN-tagged, the switch will tag the packet with the
default VLAN of the port receiving the packet. In this case, the port priority of the
port receiving the packet is assigned to the 802.1p priority of the VLAN tag of the
packet. In this case, you can set the port priority.
If the inbound packet is VLAN-tagged, the switch does not perform the operation
above.
Configuration prerequisites
■ The port whose priority is to be configured is specified
■ The priority value of the specified port is specified
Configuration procedure
Table 531 QoS functions supported by the Switch 7750 and related commands
QoS Description Related command
Priority mapping Support only the mapping
between 802.1p priority and
local queues
qos
cos-local-precedence-map
Port priority Supported priority priority-level
Priority to be used when a
packet enters a queue
Supported priority-trust
TP Supported traffic-limit
Priority remark Supported traffic-priority
Redirect Supported traffic-redirect
Queue scheduling Support SP and WRR queue-scheduler
Rate limit Supported line-rate
Bandwidth assurance Supported traffic-bandwidth
Congestion avoidance Support the RED operation traffic-red
Traffic statistics Supported traffic-statistic
Inbound CAR Supported inboundcar { enable |
disable }
Traffic-based selective QinQ Supported traffic-remark
Table 532 Set to use the port priority
Operation Command Description
Enter system view system-view -