Enhanced Transmission Selection (ETS) is a
network scheduler
A network scheduler, also called packet scheduler, queueing discipline (qdisc) or queueing algorithm, is an arbiter on a node in a packet switching communication network. It manages the sequence of network packets in the transmit and receive q ...
scheduling algorithm that has been defined by the
Data Center Bridging
Data center bridging (DCB) is a set of enhancements to the Ethernet local area network communication protocol for use in data center environments, in particular for use with clustering and storage area networks.
Motivation
Ethernet is the primar ...
Task Group of the
IEEE 802.1 Working Group. It is a hierarchical scheduler that combines static priority scheduling and a bandwidth sharing algorithms (such as
Weighted round robin
Weighted round robin (WRR) is a network scheduler for data flows, but also used to schedule processes.
Weighted round robin is a generalisation of round-robin scheduling. It serves a set of queues or tasks. Whereas round-robin cycles over the q ...
or
Deficit round robin
Deficit Round Robin (DRR), also Deficit Weighted Round Robin (DWRR), is a scheduling algorithm for the network scheduler. DRR is, like weighted fair queuing (WFQ), a packet-based implementation of the ideal Generalized Processor Sharing (GPS) poli ...
).
Description
The Enhanced Transmission Selection algorithm is one scheduling algorithm supported by
IEEE 802.1Q. In Enhanced Transmission Selection, they are two types or queues: Strict priority or
Credit-based queues, and bandwidth-assigned queues. Each bandwidth-assigned queue has a bandwidth parameter, and the total for all bandwidth-assigned queue must be 100%.
If there is no frame ready for transmission, in the Strict priority and Credit-based queues, a frame from the bandwidth-assigned queue can be transmitted. A bandwidth-sharing algorithm is in charge of selecting the queue such that the bandwidth consumed by each queue approaches its percentage of the bandwidth leftover by the Strict priority and Credit-based queues. If a queue uses less than its percentage, the remainder of its percentage used by other queues.
The standard does not specify which bandwidth-sharing algorithm must be used ''since there are a number of variants of bandwidth sharing algorithm'', but gives some constraints and references
Weighted round robin
Weighted round robin (WRR) is a network scheduler for data flows, but also used to schedule processes.
Weighted round robin is a generalisation of round-robin scheduling. It serves a set of queues or tasks. Whereas round-robin cycles over the q ...
. Th
Linux implementation of ETSdoes not consider Credit-based queues and uses
Deficit round robin
Deficit Round Robin (DRR), also Deficit Weighted Round Robin (DWRR), is a scheduling algorithm for the network scheduler. DRR is, like weighted fair queuing (WFQ), a packet-based implementation of the ideal Generalized Processor Sharing (GPS) poli ...
as bandwidth-sharing algorithm. ETS is also implemented in Microsoft Network Drivers
[
]
See also
*
Deficit round robin
Deficit Round Robin (DRR), also Deficit Weighted Round Robin (DWRR), is a scheduling algorithm for the network scheduler. DRR is, like weighted fair queuing (WFQ), a packet-based implementation of the ideal Generalized Processor Sharing (GPS) poli ...
*
Fairness measure Fairness measures or metrics are used in network engineering to determine whether users or applications are receiving a fair share of system resources. There are several mathematical and conceptual definitions of fairness.
TCP fairness
Congestio ...
*
Max-min fairness
In communication networks, multiplexing and the division of scarce resources, max-min fairness is said to be achieved by an allocation if and only if the allocation is feasible and an attempt to increase the allocation of any participant necessari ...
*
Scheduling algorithm
In computing, scheduling is the action of assigning ''resources'' to perform ''tasks''. The ''resources'' may be processors, network links or expansion cards. The ''tasks'' may be threads, processes or data flows.
The scheduling activity is c ...
*
Statistical time division multiplexing
Statistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation (DBA). In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bitrate digital channels or ...
*
Weighted round robin
Weighted round robin (WRR) is a network scheduler for data flows, but also used to schedule processes.
Weighted round robin is a generalisation of round-robin scheduling. It serves a set of queues or tasks. Whereas round-robin cycles over the q ...
*
Data center bridging
Data center bridging (DCB) is a set of enhancements to the Ethernet local area network communication protocol for use in data center environments, in particular for use with clustering and storage area networks.
Motivation
Ethernet is the primar ...
802.1Qazworking group home page
References
{{reflist
Network scheduling algorithms