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D-Link DCS-6112 /6113 User Manual
Configuration
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.
QoS/DSCP
DSCP-ECN defines QoS at Layer 3 (Network Layer). The Differentiated Services
(DiffServ) model is based on packet marking and router queuing disciplines. The
marking is done by adding a field to the IP header, called the DSCP (Differentiated
Services Code Point). This is a 6-bit field that provides 64 different class IDs. It gives an
indication of how a given packet is to be forwarded, known as the Per Hop Behavior
(PHB). The PHB describes a particular service level in terms of bandwidth, queuing
theory, and dropping (discarding the packet) decisions. Routers at each network node
classify packets according to their DSCP value and give them a particular forwarding
treatment. For example, how much bandwidth should be reserved.
Summary of Contents for DCS-6112
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