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Operating Manual
MAN_EL-1000-4GM
Version:
2.6.1
/ 01.02.2021
Authorized by:
T.W.
Page 60 of 77
Class of Service first: Packets with COS information in the VLAN tag are prioritized after this.
Packets without CoS information are prioritized according to the ToS field in the IP header or
according to port priority in case of a missing ToS field.
Type of Service first: Packets with ToS field in the IP header are prioritized after this. Packets
without ToS information are prioritized according to the CoS field in the VLAN tag or according
to port priority in case of a missing VLAN tag.
Output: Priority mode
Strict priority diagram: In case of a strict priority diagram, all of the packets from the higher
priority queue are sent first, and then packets from the next lower priority queue are sent.
8-4-2-1 weighted sequence: After 8 packets in the highest priority queue have been sent, 4
packets in the second-highest, 2 packets in the third-highest, and 1 packet in the lowest priority
queue will be sent. This approach avoids extreme waiting times for packets with the lowest
priority.
Note: If Quality of Service is used, the flow control must be switched off, since activated flow control
will transfer data packets throttled and independent of the priority (see section 5.6).
Attention! If the device is used in a Profinet setup it is highly recommended to enable the Quality of
Service feature and use a weighted fair scheduling (8-4-2-1 Priority Mode). Furthermore either COS
only mode or COS first mode with highest priority for traffic classes 6 (Internetwork Control) and 7
(Network Control) should be configured in order to allow secure and reliable communication in
automation networks.