D-Link DCS-3511 User Manual page 51

Configuration
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.
CoS
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
prioritization from 0~7 (Eight different classes of service are available). The priority
is set up on the network switches, which then use different queuing disciplines to
forward the packets.
Please follow the steps below to enable CoS settings:
1. Click Enable CoS
2. Enter the VLAN ID of your switch (0~4095)
3. Choose the priority for each application (0~7).
Note:
• The 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 only offer a "best-effort." Users can think
of CoS as "coarsely-grained" traffic control and QoS as "finely-grained" traffic
control.
• Though CoS is simple to manage, it lacks scalability and does not offer end-to-
end guarantees since it is based on L2 protocol.
D-Link DCS-3511/DCS-3530 User Manual 51