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+.TH DCB-REWR 8 "15 may 2023" "iproute2" "Linux"
+.SH NAME
+dcb-rewr \- show / manipulate the rewrite table of
+the DCB (Data Center Bridging) subsystem
+.SH SYNOPSIS
+.sp
+.ad l
+.in +8
+
+.ti -8
+.B dcb
+.RI "[ " OPTIONS " ] "
+.B rewr
+.RI "{ " COMMAND " | " help " }"
+.sp
+
+.ti -8
+.B dcb rewr " { " show " | " flush " } " dev
+.RI DEV
+.RB "[ " prio-dscp " ]"
+.RB "[ " prio-pcp " ]"
+
+.ti -8
+.B dcb rewr " { " add " | " del " | " replace " } " dev
+.RI DEV
+.RB "[ " prio-dscp " " \fIDSCP-MAP\fB " ]"
+.RB "[ " prio-pcp " " \fIPCP-MAP\fB " ]"
+
+.ti -8
+.IR DSCP-MAP " := [ " DSCP-MAP " ] " DSCP-MAPPING
+
+.ti -8
+.IR DSCP-MAPPING " := " \fIPRIO \fB:\fR "{ " DSCP " | " \fBall\fR " }"
+
+.ti -8
+.IR PCP-MAP " := [ " PCP-MAP " ] " PCP-MAPPING
+
+.ti -8
+.IR PCP-MAPPING " := " \fIPRIO \fB:\fR PCP\fR
+
+.ti -8
+.IR DSCP " := { " \fB0\fR " .. " \fB63\fR " }"
+
+.ti -8
+.IR PCP " := { " \fB0(nd/de)\fR " .. " \fB7(nd/de)\fR " }"
+
+.ti -8
+.IR PRIO " := { " \fB0\fR " .. " \fB7\fR " }"
+
+.SH DESCRIPTION
+
+.B dcb rewr
+is used to configure the rewrite table, in the DCB (Data Center Bridging)
+subsystem.  The rewrite table is used to rewrite certain values in the packet
+headers, based on packet priority.
+
+DCB rewrite entries are, like DCB APP entries, 3-tuples of selector, protocol
+ID, and priority. Selector is an enumeration that picks one of the
+prioritization namespaces. Currently, only the DSCP and PCP selector namespaces
+are supported by dcb rewr.
+
+The rewrite table is a list of DCB rewrite rules, that applies to packets
+with matching priority.  Notably, it is valid to have conflicting rewrite
+assignment for the same selector and priority. For example, the set of two
+rewrite entries (DSCP, 10, 1) and (DSCP, 11, 1), where packets with priority 1
+should have its DSCP value rewritten to both 10 and 11, form a well-defined
+rewrite table.
+.B dcb rewr
+tool allows low-level management of the rewrite table by adding and deleting
+individual rewrite 3-tuples through
+.B add
+and
+.B del
+commands. On the other hand, the command
+.B 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
+rewrite rule is in effect for a given selector and priority.
+
+.SH COMMANDS
+
+.TP
+.B show
+Display all entries with a given selector. When no selector is given, shows all
+rewrite table entries categorized per selector.
+
+.TP
+.B flush
+Remove all entries with a given selector. When no selector is given, removes all
+rewrite table entries.
+
+.TP
+.B add
+.TQ
+.B del
+Add and, respectively, remove individual rewrite 3-tuples to and from the DCB
+rewrite table.
+
+.TP
+.B replace
+Take the list of entries mentioned as parameter, and add those that are not
+present in the rewrite table yet. Then remove those entries, whose selector and
+priority have been mentioned as parameter, but not with the exact same
+protocol ID. This has the effect of, for the given selector and priority,
+causing that the table only contains the protocol ID (or ID's) given as
+parameter.
+
+.SH PARAMETERS
+
+The following table shows parameters in a way that they would be used with
+\fBadd\fR, \fBdel\fR and \fBreplace\fR commands. For \fBshow\fR and
+\fBflush\fR, the parameter name is to be used as a simple keyword without
+further arguments.
+
+.TP
+.B prio-dscp \fIDSCP-MAP
+\fIDSCP-MAP\fR uses the array parameter syntax, see
+.BR dcb (8)
+for details. Keys are priorities, values are DSCP points for traffic
+with matching priority. DSCP points can be written either directly as numeric
+values, or using symbolic names specified in
+.B /etc/iproute2/rt_dsfield
+(however note that the file specifies full 8-bit dsfield values, whereas
+.B dcb rewr
+will only use the higher six bits).
+.B dcb rewr show
+will similarly format DSCP values as symbolic names if possible. The
+command line option
+.B -N
+turns the show translation off.
+
+.TP
+.B prio-pcp \fIPCP-MAP
+\fIPCP-MAP\fR uses the array parameter syntax, see
+.BR dcb (8)
+for details. Keys are priorities. Values are PCP/DEI for traffic with
+matching priority. PCP/DEI values are written as a combination of numeric- and
+symbolic values, to accommodate for both. PCP always in numeric 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 1:2de translates to a mapping of priority 1 to PCP=2 and DEI=1.
+
+.SH EXAMPLE & USAGE
+
+Add a rule to rewrite DSCP to 0, 24 and 48 for traffic with priority 0, 3 and
+6, respectively:
+.P
+# dcb rewr add dev eth0 prio-dscp 0:0 3:24 6:48
+
+Add a rule to rewrite DSCP to 25 for traffic with priority 3:
+.P
+# dcb rewr add dev eth0 prio-dscp 3:25
+.br
+# dcb rewr show dev eth0 prio-dscp
+.br
+prio-dscp 0:0 3:CS3 3:25 6:CS6
+.br
+# dcb -N rewr show dev eth0 prio-dscp
+.br
+prio-dscp 0:0 3:24 3:25 6:48
+
+Reconfigure the table so that only one rule exists for rewriting traffic with
+priority 3.
+
+.P
+# dcb rewr replace dev eth0 prio-dscp 3:26
+.br
+# dcb rewr -N show dev eth0 prio-dscp
+.br
+prio-dscp 0:0 3:26 6:48
+
+Flush all DSCP rules:
+
+.P
+# dcb rewr flush dev eth0 prio-dscp
+.br
+# dcb rewr show dev eth0 prio-dscp
+.br
+(nothing)
+
+Add a rule to rewrite PCP to 1 and DEI to 0 for traffic with priority 1 and a
+rule to rewrite PCP to 2 and DEI to 1 for traffic with priority 2:
+
+.P
+# dcb rewr add dev eth0 prio-pcp 1:1nd 2:2de
+.br
+# dcb rewr show dev eth0 prio-pcp
+.br
+prio-pcp 1:1nd 2:2de
+
+.SH EXIT STATUS
+Exit status is 0 if command was successful or a positive integer upon failure.
+
+.SH SEE ALSO
+.BR dcb (8)
+.BR dcb-app (8)
+.BR dcb-apptrust (8)
+
+.SH REPORTING BUGS
+Report any bugs to the Network Developers mailing list
+.B <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.
+
+.SH AUTHOR
+Daniel Machon <daniel.machon@microchip.com>