VIVOTEK FE8171V Manuel D’Utilisation

 

 

 

Advanced Mode

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 priority level, your network switch will handle video packets first.

► A VLAN-capable Switch (802.1p) is required. 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.