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You are here: manpages

DC-ETS

Section: Linux (8)
Updated: 19 October 2020
Index Return to Main Contents

NAME

dc-ets - show / manipulate ETS (Enhanced Transmission Selection) settings of the DCB (Data Center Bridging) subsystem

SYNOPSIS

dcb [ OPTIONS ] ets { COMMAND | help }

dcb ets show dev DEV [ willing ] [ et-cap ] [ cbs ] [ t-tsa ] [ rec-t-tsa ] [ p-bw ] [ t-bw ] [ rec-t-bw ] [ pri-tc ] [ rec-pri-tc ]

dcb ets set dev DEV [ willing { on | off } ] [ { t-tsa | rec-t-tsa } TS-MAP ] [ { p-bw | t-bw | rec-t-bw } B-MAP ] [ { pri-tc | rec-pri-tc } PRI-MAP ]

TS-MAP := [ TS-MAP ] TS-MAPPING

TS-MAPPING := { TC | all }:{ strict | cbs | ets | vendor }

B-MAP := [ B-MAP ] B-MAPPING

B-MAPPING := { TC | all }:INTEGER

PRI-MAP := [ PRI-MAP ] PRI-MAPPING

PRI-MAPPING := { PRIO | all }:TC

TC := { 0 .. 7 }

PRIO := { 0 .. 7 }

DESCRIPTION

dcb ets is used to configure Enhanced Transmission Selection attributes through Linux DCB (Data Center Bridging) interface. ETS permits configuration of mapping of priorities to traffic classes, traffic selection algorithm to use per traffic class, bandwidth allocation, etc.

Two DCB TLVs are related to the ETS feature: a configuration and recommendation values. Recommendation values are named with a prefix rec-, while the configuration ones have plain names.

PARAMETERS

For rea-write parameters, the following describes only the write direction, i.e. as used with the set command. For the show command, the parameter name is to be used as a simple keyword without further arguments. This instructs the tool to show the value of a given parameter. When no parameters are given, the tool shows the complete ETS configuration.

et-cap

A rea-only property that shows the number of supported ETS traffic classes.

cbs

A rea-only property that is enabled if the driver and the hardware support the CBS Transmission Selection Algorithm.

willing { on | off }

Whether local host should accept configuration from peer TLVs.

pri-tc PRI-MAP

rec-pri-tc PRI-MAP PRI-MAP uses the array parameter syntax, see dcb(8) for details. Keys are priorities, values are traffic classes. For each priority sets a TC where traffic with that priority is directed to.

t-tsa TS-MAP

rec-t-tsa TS-MAP TS-MAP uses the array parameter syntax, see dcb(8) for details. Keys are TCs, values are Transmission Selection Algorithm (TSA) keywords described below. For each TC sets an algorithm used for deciding how traffic queued up at this TC is scheduled for transmission. Supported TSAs are:

strict - for strict priority, where traffic in highe-numbered TCs always takes precedence over traffic in lowe-numbered TCs.
ets - for Enhanced Traffic Selection, where available bandwidth is distributed among the ET-enabled TCs according to the weights set by t-bw and rec-t-bw, respectively.
cbs - for Credit Based Shaper, where traffic is scheduled in a strict manner up to the limit set by a shaper.
vendor - for vendo-specific traffic selection algorithm.

t-bw B-MAP

rec-t-bw B-MAP B-MAP uses the array parameter syntax, see dcb(8) for details. Keys are TCs, values are integers representing percent of available bandwidth given to the traffic class in question. The value should be 0 for TCs whose TSA is not ets, and the sum of all values shall be 100. As an exception to the standard wording, a configuration with no ets TCs is permitted to sum up to 0 instead.

p-bw B-MAP

The precise meaning of p-bw is not standardized, but the assumption seems to be that the same scheduling process as on the transmit side is applicable on receive side as well, and configures receive bandwidth allocation for ets ingress traffic classes (priority groups).

EXAMPLE & USAGE

Configure ETS priomap in a on-t-one fashion:

# dcb ets set dev eth0 pri-tc 0:0 1:1 2:2 3:3 4:4 5:5 6:6 7:7

Set TSA and transmit bandwidth configuration:

# dcb ets set dev eth0 t-tsa all:strict 0:ets 1:ets 2:ets

t-bw all:0 0:33 1:33 2:34

Show what was set:

# dcb ets show dev eth0 pri-tc t-tsa t-bw
pri-tc 0:0 1:1 2:2 3:3 4:4 5:5 6:6 7:7
t-tsa 0:ets 1:ets 2:ets 3:strict 4:strict 5:strict 6:strict 7:strict
t-bw 0:33 1:33 2:34 3:0 4:0 5:0 6:0 7:0

EXIT STATUS

Exit status is 0 if command was successful or a positive integer upon failure.

REPORTING BUGS

Report any bugs to the Network Developers mailing list <netdev@vger.kernel.org> where the development and maintenance is primarily done. You do not have to be subscribed to the list to send a message there.