# dcb-app

## 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.
    


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