Vivotek IP8352 Network > QoS Quality of Service, Requirements for QoS, CoS the VLAN 8021p model

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Network > QoS (Quality of Service)

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.

NOTE:

►A VLAN 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�

User's Manual - 63