Vivotek FD8371EV User Manual download pdf (Page 84)

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84 - User's Manual

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 insufcient, especially for real-time streaming multimedia applications. Quality

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

The following are the main benets of a QoS-aware network:

■

The ability to prioritize trafc and guarantee a certain level of performance to the data ow.

■

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 denes 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 rst.

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

►The 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" trafc

control and QoS as "nely-grained" trafc 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.

NOTE:

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Vivotek FD8371EV User Manual Page 84