DCB-APP(8)			     Linux			    DCB-APP(8)

NAME
       dcb-app - show / manipulate application priority table of the DCB (Data
       Center Bridging) subsystem

SYNOPSIS

       dcb [ OPTIONS ]	app { COMMAND | help }


       dcb app	{  show	 |  flush  }  dev DEV [ default-prio ] [ ethtype-prio
	       ] [ stream-port-prio ] [ dgram-port-prio ] [ port-prio ] [
	       dscp-prio ] [ pcp-prio ]

       dcb app	{  add	|  del	|  replace  }  dev DEV [ default-prio
	       PRIO-LIST ] [ ethtype-prio ET-MAP ] [ stream-port-prio PORT-MAP
	       ] [ dgram-port-prio PORT-MAP ] [ port-prio PORT-MAP ] [
	       dscp-prio DSCP-MAP ] [ pcp-prio PCP-MAP ]

       PRIO-LIST := [ PRIO-LIST ] PRIO

       ET-MAP := [ ET-MAP ] ET-MAPPING

       ET-MAPPING := ET:PRIO

       PORT-MAP := [ PORT-MAP ] PORT-MAPPING

       PORT-MAPPING := PORT:PRIO

       DSCP-MAP := [ DSCP-MAP ] DSCP-MAPPING

       DSCP-MAPPING := { DSCP | all }:PRIO

       PCP-MAP := [ PCP-MAP ] PCP-MAPPING

       PCP-MAPPING := PCP:PRIO

       ET := { 0x600 .. 0xffff }

       PORT := { 1 .. 65535 }

       DSCP := { 0 .. 63 }

       PCP := { 0(nd/de) .. 7(nd/de) }

       PRIO := { 0 .. 7 }


DESCRIPTION
       dcb app is used to configure APP table, or application priority table
       in the DCB (Data Center Bridging) subsystem. The APP table is used to
       assign priority to traffic based on value in one of several headers:
       EtherType, L4 destination port, or DSCP. It also allows configuration
       of port-default priority that is chosen if no other prioritization rule
       applies.

       DCB APP entries are 3-tuples of selector, protocol ID, and priority.
       Selector is an enumeration that picks one of the prioritization
       namespaces. Currently it mostly corresponds to configurable parameters
       described below. Protocol ID is a value in the selector namespace. E.g.
       for EtherType selector, protocol IDs are the individual EtherTypes, for
       DSCP they are individual code points. The priority is the priority that
       should be assigned to traffic that matches the selector and protocol
       ID.

       The APP table is a set of DCB APP entries. The only requirement is that
       duplicate entries are not added. Notably, it is valid to have
       conflicting priority assignment for the same selector and protocol ID.
       For example, the set of two APP entries (DSCP, 10, 1) and (DSCP, 10,
       2), where packets with DSCP of 10 should get priority of both 1 and 2,
       form a well-defined APP table. The dcb app tool allows low-level
       management of the app table by adding and deleting individual APP
       3-tuples through add and del commands. On the other hand, the command
       replace does what one would typically want in this situation--first
       adds the new configuration, and then removes the obsolete one, so that
       only one prioritization is in effect for a given selector and protocol
       ID.


COMMANDS
       show   Display all entries with a given selector. When no selector is
	      given, shows all APP table entries categorized per selector.


       flush  Remove all entries with a given selector. When no selector is
	      given, removes all APP table entries.


       add
       del    Add and, respectively, remove individual APP 3-tuples to and
	      from the DCB APP table.


       replace
	      Take the list of entries mentioned as parameter, and add those
	      that are not present in the APP table yet. Then remove those
	      entries, whose selector and protocol ID have been mentioned as
	      parameter, but not with the exact same priority. This has the
	      effect of, for the given selector and protocol ID, causing that
	      the table only contains the priority (or priorities) given as
	      parameter.


PARAMETERS
       The following table shows parameters in a way that they would be used
       with add, del and replace commands. For show and flush, the parameter
       name is to be used as a simple keyword without further arguments.


       default-prio PRIO-LIST
	      The priority to be used for traffic the priority of which is
	      otherwise unspecified. The argument is a list of individual
	      priorities. Note that default-prio rules are configured as
	      triplets (EtherType, 0, PRIO).  dcb app translates these rules
	      to the symbolic name default-prio and back.


       ethtype-prio ET-MAP
	      ET-MAP uses the array parameter syntax, see dcb(8) for details.
	      Keys are EtherType values. Values are priorities to be assigned
	      to traffic with the matching EtherType.


       stream-port-prio PORT-MAP
       dgram-port-prio PORT-MAP
       port-prio PORT-MAP
	      PORT-MAP uses the array parameter syntax, see dcb(8) for
	      details. Keys are L4 destination port numbers that match on,
	      respectively, TCP and SCTP traffic, UDP and DCCP traffic, and
	      either of those. Values are priorities that should be assigned
	      to matching traffic.


       dscp-prio DSCP-MAP
	      DSCP-MAP uses the array parameter syntax, see dcb(8) for
	      details. Keys are DSCP points, values are priorities assigned to
	      traffic with matching DSCP. DSCP points can be written either
	      directly as numeric values, or using symbolic names specified in
	      /etc/iproute2/rt_dsfield (however note that the file specifies
	      full 8-bit dsfield values, whereas dcb app will only use the
	      higher six bits).	 dcb app show will similarly format DSCP
	      values as symbolic names if possible. The command line option -N
	      turns the show translation off.


       pcp-prio PCP-MAP
	      PCP-MAP uses the array parameter syntax, see dcb(8) for details.
	      Keys are PCP/DEI. Values are priorities assigned to traffic with
	      matching PCP/DEI. PCP/DEI values are written as a combination of
	      numeric- and symbolic values, to accommodate for both. PCP
	      always in numerical form e.g 0 .. 7 and DEI in symbolic form e.g
	      'de' (drop-eligible), indicating that the DEI bit is 1 or 'nd'
	      (not-drop-eligible), indicating that the DEI bit is 0.  In
	      combination 2de:1 translates to a mapping of PCP=2 and DEI=1 to
	      priority 1.


EXAMPLE & USAGE
       Prioritize traffic with DSCP 0 to priority 0, 24 to 3 and 48 to 6:


       # dcb app add dev eth0 dscp-prio 0:0 24:3 48:6

       Add another rule to configure DSCP 24 to priority 2 and show the
       result:


       # dcb app add dev eth0 dscp-prio 24:2
       # dcb app show dev eth0 dscp-prio
       dscp-prio 0:0 CS3:2 CS3:3 CS6:6
       # dcb -N app show dev eth0 dscp-prio
       dscp-prio 0:0 24:2 24:3 48:6

       Reconfigure the table so that the only rule for DSCP 24 is for
       assignment of priority 4:


       # dcb app replace dev eth0 dscp-prio 24:4
       # dcb app -N show dev eth0 dscp-prio
       dscp-prio 0:0 24:4 48:6

       Flush all DSCP rules:


       # dcb app flush dev eth0 dscp-prio
       # dcb app show dev eth0 dscp-prio
       (nothing)

       Add a rule to map traffic with PCP 1 and DEI 0 to priority 1 and PCP 2
       and DEI 1 to priority 2:


       # dcb app add dev eth0 pcp-prio 1nd:1 2de:2
       # dcb app show dev eth0 pcp-prio
       pcp-prio 1nd:1 2de:2


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


SEE ALSO
       dcb(8)


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.


AUTHOR
       Petr Machata <me@pmachata.org>

iproute2			6 December 2020			    DCB-APP(8)