Airlive POE-GSH2404M handleiding
Handleiding
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16 QoS
QoS (Quality of Service) assesses the ability of service providers to meet customer
needs and the ability of transmitting packets over the Internet. Diversified services can
be assessed based on different aspects. QoS usually refers to the evaluation of service
capabilities that support core requirements such as bandwidth, delay, delay variation,
and packet loss rate during delivery. Bandwidth, also known as throughput, refers to the
average business flow within a certain period of time, with the unit of Kbit/s. Delay refers to
the average time required for business flowing through the network. For a network device,
the followings are general levels of delay requirements. There are two delay levels, that
is, the high-priority business can be served as soon as possible by scheduling method of
priority queue, while the low-priority business gets services after that. Delay variation refers
to the time change of business flowing through the network. Packet loss rate refers to the
percentage of lost business flow during transmission. As modern transmission systems
are very reliable, information is often lost in network congestion. Packet loss due to queue
overflow is the most common situation.
All messages in a traditional IP network are treated equally. Every network device
processes the messages on a FIFO basis, and makes every effort to transmit them to
destinations without guaranteeing reliability, transfer delay, or other performance.
Network service quality is constantly improved as new applications keep springing
up in the rapidly changing IP network. For example, VoIP, video and other delay-sensitive
services have set higher standards on message transmission delay. Message transmission
in a short period has been the common trend. In order to support voice, video and data
services with different requirements, the network needs to identify business types and
provide corresponding services.
The ability to distinguish business types is the prerequisite to provide corresponding
services, so the traditional best-effort service no longer meets the application needs.
Therefore, QoS comes into being. It regulates the network flow to avoid and handle network
congestion and reduce packet loss rate. Meanwhile, users can enjoy dedicated bandwidths
while business can improve service quality, thus perfecting the network service capacity.
QoS priorities vary with message types. For instance, the VLAN message uses
802.1p, also known as the CoS (Class of Service) field, while the IP message uses DSCP.
To maintain the priority, these fields need to be mapped at the gateway connected with
various networks when messages flow through the network.
802.1p priority in the VLAN frame header
Typically, VLAN frames are interacted between Layer 2 devices. The PRI field (i.e.
802.1p priority), or CoS field, in the VLAN frame header identifies the quality of service
requirements according to the definitions in IEEE 802.1Q.
802.1p priority in the VLAN frame
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Productinformatie
| Merk | Airlive |
| Model | POE-GSH2404M |
| Categorie | Niet gecategoriseerd |
| Taal | Nederlands |
| Grootte | 72641 MB |
