DCB(8)                  (19 October 2020)                  DCB(8)

     NAME
          dcb - show / manipulate DCB (Data Center Bridging) settings

     SYNOPSIS
          dcb [ OPTIONS ] { app | buffer | ets { COMMAND | help }

          dcb [ -force ] -batch filename

          dcb [ OPTIONS ] help

     OPTIONS
          -n, --netns <NETNS>
               switches dcb to the specified network namespace NETNS.

          -V, --Version
               Print the version of the dcb utility and exit.

          -b, --batch <FILENAME>
               Read commands from provided file or standard input and
               invoke them. First failure will cause termination of
               dcb.

          -f, --force
               Don't terminate dcb on errors in batch mode. If there
               were any errors during execution of the commands, the
               application return code will be non zero.

          -i, --iec
               When showing rates, use ISO/IEC 1024-based prefixes
               (Ki, Mi, Bi) instead of the 1000-based ones (K, M, B).

          -j, --json
               Generate JSON output.

          -N, --Numeric
               If the subtool in question translates numbers to sym-
               bolic names in some way, suppress this translation.

          -p, --pretty

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               When combined with -j generate a pretty JSON output.

          -s, --statistics
               If the object in question contains any statistical
               counters, shown them as part of the "show" output.

     OBJECTS
          app  - Configuration of application priority table

          buffer
               - Configuration of port buffers

          ets  - Configuration of ETS (Enhanced Transmission Selec-
               tion)

          maxrate
               - Configuration of per-TC maximum transmit rate

          pfc  - Configuration of PFC (Priority-based Flow Control)

     COMMANDS
          A COMMAND specifies the action to perform on the object. The
          set of possible actions depends on the object type. As a
          rule, it is possible to show objects and to invoke topical
          help, which prints a list of available commands and argument
          syntax conventions.

     ARRAY PARAMETERS
          Like commands, specification of parameters is in the domain
          of individual objects (and their commands) as well. However,
          much of the DCB interface revolves around arrays of fixed
          size that specify one value per some key, such as per traf-
          fic class or per priority. There is therefore a single syn-
          tax for adjusting elements of these arrays. It consists of a
          series of KEY:VALUE pairs, where the meaning of the individ-
          ual keys and values depends on the parameter.

          The elements are evaluated in order from left to right, and
          the latter ones override the earlier ones. The elements that
          are not specified on the command line are queried from the
          kernel and their current value is retained.

          As an example, take a made-up parameter tc-juju, which can
          be set to charm traffic in a given TC with either good luck

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          or bad luck. KEY can therefore be 0..7 (as is usual for TC
          numbers in DCB), and VALUE either of none, good, and bad. An
          example of changing a juju value of TCs 0 and 7, while leav-
          ing all other intact, would then be:

          # dcb foo set dev eth0 tc-juju 0:good 7:bad

          A special key, all, is recognized which sets the same value
          to all array elements. This can be combined with the usual
          single-element syntax. E.g. in the following, the juju of
          all keys is set to none, except 0 and 7, which have other
          values:

          # dcb foo set dev eth0 tc-juju all:none 0:good 7:bad

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

     SEE ALSO
          dcb-app(8), dcb-buffer(8), dcb-ets(8), dcb-maxrate(8),
          dcb-pfc(8)

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

     AUTHOR
          Petr Machata <me@pmachata.org>

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