VIVOTEK FD8167-(T) 사용자 설명서

 

 

 

Quality of Service refers to a resource reservation control mechanism, which guarantees a certain 

quality to different services on the network� Quality of service guarantees are important if the 

network capacity is insufficient, especially for real-time streaming multimedia applications. Quality 

can be defined as, for instance, a maintained level of bit rate, low latency, no packet dropping, etc.

The following are the main benefits of a QoS-aware network:

■ 

The ability to prioritize traffic and guarantee a certain level of performance to the data flow. 

■ 

The ability to control the amount of bandwidth each application may use, and thus provide higher 

reliability and stability on the network�

Requirements for QoS

To utilize QoS in a network environment, the following requirements must be met:

■ 

All network switches and routers in the network must include support for QoS� 

■ 

The network video devices used in the network must be QoS-enabled�

QoS models

CoS (the VLAN 802�1p model)

IEEE802.1p defines a QoS model at OSI Layer 2 (Data Link Layer), which is called CoS, Class of 

Service� It adds a 3-bit value to the VLAN MAC header, which indicates the frame priority level from 

0 (lowest) to 7 (highest)� The priority is set up on the network switches, which then use different 

queuing disciplines to forward the packets�

Below is the setting column for CoS� Enter the 

VLAN ID of your switch (0~4095) and choose the 

priority for each application (0~7).

If you assign Video the highest level, the switch will handle video packets first.

► A VLAN Switch (802.1p) is required. The web browsing may fail if the CoS setting is incorrect.

► Class of Service technologies do not guarantee a level of service in terms of bandwidth and 

delivery time; they offer a "best-effort�" Users can think of CoS as "coarsely-grained" traffic 

control and QoS as "finely-grained" traffic control.

► Although CoS is simple to manage, it lacks scalability and does not offer end-to-end guarantees 

since it is based on L2 protocol�