3Com Switch 7757, Configuration Manual

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ONFIGURATION
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Type-A I/O Modules include 3C16860, 3C16861, LS81FS24A, 3C16858,
3C16859, 3C16860, 3C16861, LS81FS24, 3C16858, and 3C16859.
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On type-A I/O Modules, the prompt for QoS view is qoss ; on non-type-A I/O
Modules, the prompt for QoS view is qosb .
Overview
Quality of Service (QoS) is a concept generally existing in occasions with service
supply and demand. It evaluates the ability to meet the need of the customers in
service. Generally, the evaluation is not to grade precisely. Its purpose is to analyze
the conditions when the service is the best and the conditions when the service
still needs improvement and then to make improvements in the specified aspects.
In internet, QoS evaluates the ability of the network to deliver packets. The
evaluation on QoS can be based on different aspects because the network
provides various services. Generally speaking, QoS is the evaluation on the service
ability to support the core requirements such as delay, delay variation and packet
loss ratio in the packet delivery.
Traffic Traffic means service traffic, that is, all the packets passing the switch.
Traffic Classification Traffic classification means to identify packets conforming to certain characters
according to certain rules.
A classification rule is a filter rule configured to meet your management
requirements. It can be very simple. For example, you can use a classification rule
to identify traffic with different priorities according to the ToS field in the IP packet
header. It can be very complicated too. For example, you can use a classification
rule to identify the packets according to the combination of link layer (Layer 2),
network layer (Layer 3) and transport layer (Layer 4) information including MAC
addresses, IP protocols, source addresses, destination addresses, the port numbers
of applications and so on.
Classification is generally based on the information in the packet header and rarely
based on the packet content.