phpman > man > dcb-app(8)

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DCB-ETS(8) Linux DCB-ETS(8)

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

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 enumera‐
tion that picks one of the prioritization namespaces. Currently it mostly corresponds to con‐
figurable 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 indi‐
vidual 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 other hand, the command
replace does what one would typically want in this situation--first adds the new configura‐
tion, 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 pri‐
ority (or priorities) given as parameter.

PARAMETERS
The following table shows parameters in a way that they would be used with add, del and re‐‐
place 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 con‐
figured as triplets (EtherType, 0, PRIO). dcb app translates these rules to the sym‐
bolic 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 destina‐
tion 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 match‐
ing 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 direcly 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 simi‐
larly format DSCP values 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 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 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.