Industrial Ethernet Switch User Manual
3onedata proprietary and confidential
24
Copyright © 3onedata Co., Ltd.
When open port priority, must open inspect COS. The example is as figure below:
open inspect port, 1, 2, 3, 4 COS, divide port 1, 2, 3, 4 in different priority, COS value
corresponding priority no need to set up. Port 1, 2, 3, 4, port 1, the priority is the
highest. When these 4 port’s receive data must transfer from other port, because the
limited of bandwidth, will be transferred according to priority queue mechanism (If use
strict mode, then port 1’s data must be transferred over at first. If use Weighted Fair
8:4:2:1, the 4 port will be transferred according 8: 4: 2: 1 ratio)
6.2 CoS
IEEE P802.1p is the name of a task group active during 1995
–98 responsible for
adding traffic class expediting and dynamic multicast filtering to the IEEE 802.1D
standard. Essentially, they provided a mechanism for implementing Quality of Service
(QoS) at the media access control (MAC) level. The group's work with the new priority
classes and Generic Attribute Registration Protocol (GARP) was not published
separately but was incorporated into a major revision of the standard, IEEE
802.1D-1998. It also required a short amendment extending the frame size of the
Ethernet standard by four bytes which was published as IEEE 802.3ac in 1998.
The QoS technique developed by the working group, also known as class of service
(CoS), is a 3-bit field called the Priority Code Point (PCP) within an Ethernet frame
