DCB-ETS(8) Linux DCB-ETS(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 ]
dcb ets { 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 ]
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
ET := { 0x600 .. 0xffff }
PORT := { 1 .. 65535 }
DSCP := { 0 .. 63 }
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 name-
spaces. Currently it mostly corresponds to configurable parameters de-
scribed 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 conflict-
ing priority assignment for the same selector and protocol ID. For ex-
ample, 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 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 pri-
oritization 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 en-
tries, whose selector and protocol ID have been mentioned as pa-
rameter, but not with the exact same priority. This has the ef-
fect 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 pri-
orities. 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 de-
tails. Keys are L4 destination port numbers that match on, re-
spectively, TCP and SCTP traffic, UDP and DCCP traffic, and ei-
ther 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 de-
tails. 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 that file specifies
full 8-bit dsfield values, whereas dcb app will only use the
higher six bits). dcb app show will similarly format DSCP val-
ues as symbolic names if possible. The command line option -N
turns the show translation off.
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 re-
sult:
# 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 assign-
ment of priority 4:
# dcb app replace dev eth0 dscp-prio 24:4
# dcb app 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)
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 <net-
dev@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-ETS(8)
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