Amer Networks SS2R48G4i V2 - Manual (Page 186)

SS2R24G4i/SS2R48G4i
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according to the policing policies.
Queuing Egress QoS action. Put the packets to appropriate egress queues according to the packet
CoS value.
Scheduling QoS egress action. Configure the weight for eight egress queues WRR (Weighted
Round Robin).
In Profile Traffic within the QoS policing policy range (bandwidth or burst value) is called “In Profile".
Out of Profile Traffic out the QoS policing policy range (bandwidth or burst value) is called “Out of
Profile".
22.1.2 QoS Implementation
To implement switch software QoS, a general, mature reference model should be given. QoS can
not create new bandwidth, but can maximize the adjustment and configuration for the current
bandwidth resource. Fully implemented QoS can achieve complete management over the network
traffic. The following is as accurate as possible a description of QoS.
The data transfer specifications of IP cover only addresses and services of source and destination,
and ensure correct packet transmission using OSI layer 4 or above protocols such as TCP. However,
rather than provide a mechanism for providing and protecting packet transmission bandwidth, IP
provide bandwidth service by the best effort. This is acceptable for services like Mail and FTP, but for
increasing multimedia business data and e-business data transmission, this best effort method cannot
satisfy the bandwidth and low-lag requirement.
Based on differentiated service, QoS specifies a priority for each packet at the ingress. The
classification information is carried in Layer 3 IP packet header or Layer 2 802.1Q frame header. QoS
provides same service to packets of the same priority, while offers different operations for packets of
different priority. QoS-enabled switch or router can provide different bandwidth according to the
packet classification information, and can remark on the classification information according to the
policing policies configured, and may discard some low priority packets in case of bandwidth shortage.
If devices of each hop in a network support differentiated service, an end-to-end QoS solution can
be created. QoS configuration is flexible, the complexity or simplicity depends on the network topology
and devices and analysis to incoming/outgoing traffic.
22.1.3 Basic QoS Model
Classification Classify traffic according to packet classification information and generate internal
DSCP value based on the classification information. For different packet types and switch
configurations, classification is performed differently; the flowchart below explains this in detail
Policing and remark Each packet in classified ingress traffic is assigned an internal DSCP value and
can be policed and remarked.
Policing can be performed based on DSCP value to configure different policies that allocate bandwidth
to classified traffic. If the traffic exceeds the bandwidth set in the policy (out of profile), the out of profile
traffic can be allowed, discarded or remarked. Remarking uses a new DSCP value of lower priority to