IEEE 802.1Qbu-2016 pdf free download – IEEE Standard for Local and metropolitan area networks— Bridges and Bridged Networks— Amendment 26: Frame Preemption.
8. Principles of bridge operation
8.6 The Forwarding Process
8.6.8 TransmIssion selection
Insert the jóllowing immediately after 7rO1E 2:
In a port of a Bridge or station that supports frame preemption, a frame of pnority a is not available for transmission if that priority is identified in the frame preemption status table (6.7.2) as preemptable and either the Isoidkequesi object 112.30.1.5) is set to the value hold, or the transmission of a prior preeniptable frame has yet to complete because it has beets interrupted to allow the transmission of an express frame.
8.6.8.2 Credltbased shaper algorithm
Change the text of list items ci and I). and insert new NOTEs. renumbering subsequent NOTEs. as follows:
e) Iran salt, Takes the value TRUE for the duratton of a frame transmission from the queue; FALSE when any frame transmission from the queue has completed. If the credit-based shaper algorithm is used tn combination with frame preemption t6.7.2t. transmit only takes the value TRUE while the frame is actually being transtuitted by the MAC. If the frame transmission is delayed or interrupted (e.g.. the frame is a prcempt4lhle frame and its transmission is interrupted to allow the transmission of an express frame from a different queue. or the frame is an express frame and there is a delay before transmission c-an start because a preemptable frame was being tin-smitted) transmit takes the salue FALSE until transmission of the frame commences or is resumest Transmit also takes the value FALSE during the transmission of any overhead that is a conacquencejstframc preemption, i.e.. any additional frame oscthcad that is ad&d to the precmtsablc frame when prcensption occurs.
holE I—The consequciwc of this is that y osaticad associated with piceinptivn does not come uut of the tescised bandwidth tot the credit.baaed shape.
1) credit. The transmission credit, in bits, that is currently available to the queue. If, at any time, there are no frames in the queue, and the transmit parameter is FALSE, and the transniissiori gate for the queue is open (8,6.8.4), and credit is positive. ,ind there is no preeinptabk frame from this queue fiat is hich trins’msston is in progress hut ba ççn riternipied. then credit is set to zero.
IF i..;i. tb’’‘[L•’ — – – I ‘1 aist.; pr.’.’ipahte frame or pan-frame is n-all I ‘it rtubc
6.6.8.4 Enhancements for scheduled traffic
Change the second paragraph of Li L 4 as follows?
A gore conavl list associated with each Port contains an ordered list of gate operations Each gate operation changes the transmission gate state flit the gate associated with each of the Port’s traffic class queues.anti allows associated control operations to he scheduled. In an implementation that does not support enhancements for scheduled traffic, all gates are assumed to he permanently in the open state. Table 8-6 identifies the gate operation types, their parameters, and the actions that result from their execution. The state machines that control the esecution of the gate control lisi, along with their variables and procediats, are specified in 86,9.IEEE 802.1Qbu pdf download.