Hirschmann GREYHOUND GRS1020, Справочное руководство

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Network load control
10.4 QoS/Priority
125
UM Config GRS
Release 8.0 09/2019
10.4.5 Handling of traffic classes
The device provides the following options for handling traffic classes:

Strict Priority

Weighted Fair Queuing

Strict Priority combined with Weighted Fair Queuing

Queue management
Strict Priority description
With the Strict Priority setting, the device first transmits data packets that have a higher traffic class
(higher priority) before transmitting a data packet with the next highest traffic class. When there are
no other data packets remaining in the queue, the device transmits a data packet with the lowest
traffic class (lowest priority). In unfortunate cases, if there is a high volume of high-priority traffic
waiting to be sent on this port, then the device does not send packets with a low priority.
In delay-sensitive applications, such as VoIP or video, Strict Priority lets data to be sent
immediately.
Weighted Fair Queuing description
With Weighted Fair Queuing, also called Weighted Round Robin (WRR), the user assigns a
minimum or reserved bandwidth to each traffic class. This helps ensure that data packets with a
lower priority are also sent although the network is very busy.
The reserved values range from 0% through 100% of the available bandwidth, in steps of 1%.

A reservation of 0 is equivalent to a "no bandwidth" setting.

The sum of the individual bandwidths can be up to 100%.
When you assign Weighted Fair Queuing to every traffic class, the entire bandwidth of the
corresponding port is available to you.
Combining Strict Priority and Weighted Fair Queuing
When combining Weighted Fair Queuing with Strict Priority, verify that the highest traffic class of
Weighted Fair Queuing is lower than the lowest traffic class of Strict Priority.
If you combine Weighted Fair Queuing with Strict Priority, then a high Strict Priority network load
can significantly reduce the bandwidth available for Weighted Fair Queuing.
100 - Flash Override 0010 - [maximize reliability]
011 - Flash 0001 - [minimize monetary cost]
010 - Immediate
001 - Priority
000 - Routine
Table 18: ToS field in the IP header (cont.)
Bits (0-2): IP Precedence Defined Bits (3-6): Type of Service
Defined
Bit (7)