IEEE Std 802.1Qbv-2015 pdf download – Local and metropolitan area networks- Bridges and Bridged Networks Amend ment 25: Enhancements for Scheduled Traffic.
8. Principles of bridge operation 8.6 The Forwarding Process 8.6.6 Queuing frames Delete the fourth paragraph of 8.6.6 as shown: VID is not applicable to VLAN-unaware MAC Relays and the above combinations will exclude any reference to VID when applied to MAC Bridges. Change NOTE 2 of 8.6.6 as shown: NOTE 2—Different numbers of traffic classes may be implemented for different Ports can use different numbers of traffic classes. Ports with media access methods that support a single transmission priority, such as Ethernet, can support more than one traffic class. 8.6.8 Transmission selection Change the first paragraph of 8.6.8 as shown: For each Port, frames are selected for transmission on the basis of the traffic classes that the Port supports and the operation of the transmission selection algorithms supported by the corresponding queues on that Port. For a given Port and supported value of traffic class, frames are selected from the corresponding queue for transmission if and only if Insert a new paragraph at the end of 8.6.8 as shown: When the enhancements for scheduled traffic are supported, additional requirements to determine whether a frame is available for transmission apply, as specified in 8.6.8.4. 8.6.8.2 Credit-based shaper algorithm Change the text of 8.6.8.2 list item d), and add a NOTE, as shown: d) idleSlope. The rate of change of credit, in bits per second, when the value of credit is increasing (i.e., while transmit is FALSE and the transmission gate for the queue is open [8.6.8.4]). The value of idleSlope can never exceed portTransmitRate. If the enhancements for scheduled traffic (8.6.8.4) are not supported, or if GateEnabled is FALSE (8.6.9.4.14), The the value of idleSlope for a given queue is determined by equal to the value of the operIdleSlope(N) parameter for that queue, as defined in 34.3. If the enhancements for scheduled traffic (8.6.8.4) are supported, and GateEnabled is TRUE (8.6.9.4.14), then:idleSlope = (operIdleSlope(N) × OperCycleTime / GateOpenTime) where OperCycleTime is as defined in 8.6.9.4.20 and GateOpenTime is equal to the total amount of time during the gating cycle that the gate state for the queue is Open.