ethtool
ethtool ist ein Konfigurations- und Diagnosewerkzeug für kabelgebundene Netzwerkkarten
Beschreibung
- Einstellmöglichkeiten sind umfangreich
- je nach Netzwerk-Hardware und Treibermodul
- Nicht alle Konfigurationsmöglichkeiten können mit jedem Gerät umgesetzt werden
- Optimale Performance
- Netzwerkkarte optimal konfigurieren
Grundlagen
- In der Regel funktioniert eine Verbindung im Ethernet ohne weitere Konfiguration.
- Um die verfügbare Bandbreite aber optimal auszunutzen, gilt es einige Grundregeln zu beachten.
- Die Duplexeinstellungen müssen bei beiden Linkpartner gleich sein.
- Also entweder beide Seiten eines Link auf Autonegotiation oder beide Seiten fest auf die selben Parameter einstellen.
- Viele SOHO-Switche (Small Office, Home Office) bieten keine Einstellmöglichkeiten und arbeiten immer mit Autonegotiation.
- Die Netzwerkkarten der angeschlossenen Clients müssen also auch auf Auto stehen.
- Unter Linux leistet ethtool dabei gute Dienste.
Aktuelle Netzwerkkarten erkennen automatisch die möglichen Einstellungen und verbinden sich zur Gegenstelle, wie einen Netzwerk-Router oder einem Netzwerk-Switch, mit der bestmöglichen Geschwindigkeit.
- Die Konfiguration erfolgt über die sog. Autonegotiation-Funktion.
- Dazu werden die Einstellungen über ein bestimmtes Verfahren automatisch zwischen den Endgeräten ausgehandelt. Ältere Ethernet-Karten (10Base-T) verwenden das Normal-Link-Pulse-Verfahren (NLP), Fast-Ethernet (10/100MBit/s) und schnellere Karten das Fast-Link-Pulse-Verfahren (FLP).
- Die Pulse werden in regelmäßigen Abständen von einigen Millisekunden gesendet.
Durch beschädigte Kabel oder Anschlussstecker kann es trotz gelungener Verbindung dennoch zu Übertragungsfehlern kommen.
- Eine Beschädigung oder ein Bruch des Netzwerkkabels muss nicht zwingend von außen sichtbar sein.
- Ein Kabelbruch verhindert z. B.
- eine gleichzeitige Übertragung der Daten in beide Richtungen (Duplex).
- Quetschungen beeinflussen, je nach Qualität und Ausführung des Kabels, die sog.
- Durchgangsdämpfung stark und somit auch die Übertragung bzw.
- Signalqualität.
- Die Synchronisation zwischen zwei Netzwerkgeräten kann scheitern oder es kommt vermehrt zu Übertragungsfehlern.
Korrodierte Kontakte bei billigen Steckverbindern der Kabel oder der Netzwerkkarte sorgen ebenfalls für Verbindungsprobleme.
- Ein Austausch der Stecker, Kabel oder Reinigung der Kontaktflächen schafft Abhilfe.
Können durch Austausch der Kabel und einen Wechsel der verwendeten Anschlüsse am verwendeten Router oder Netzwerk-Switch Fehler ausgeschlossen werden, so ist ein Treiber- oder Konfigurationsproblem, sowie ein Defekt der Netzwerk-Karte natürlich ebenfalls möglich.
ethtool bietet hier über Terminal [2] die Möglichkeit einer Fehlerdiagnose sowie verschiedene Einstellungen der Netzwerkkarte anzupassen und zu testen.
Installation
# apt install ethtool
Syntax
Parameter
Optionen
Umgebungsvariablen
Exit-Status
Konfiguration
Dateien
Anwendung
Diagnose und Konfiguration
Die in den Beispielen verwendete Schnittstelle eth0 ist durch die Bezeichnung der tatsächlich verwendeten Netzwerkkarte zu ersetzen.
- ethtool muss in den meisten Fällen mit Root-Rechten [3] gestartet werden, um Abfragen zu ermöglichen oder Einstellungen ändern zu können.
- Hinweis
Viele Karten akzeptieren Einstellungsänderungen oft nur in Kombination unter Angabe der Parameter für Autonegotiation und Übertragungsmodus.
- Geschwindigkeit auf 100 MBit/s festlegen
# ethtool -s eth0 speed 100 duplex full autoneg on
- Hinweis
Möchte man bestimmte Einstellungen der Karte schon bei Systemstart festlegen, kann die benötigte Befehlszeile in das Startskript rc.local eingetragen werden.
Datenübertragung und Fehlerabfrage
Neben der Standardabfrage mit ifconfig liefert ethtool eine detailliertere Auswertung und Anzeige bei eventuell auftretenden Übertragungsfehlern.
Abfrage:
# ethtool -S eth0
NIC statistics:
rx_packets: 3623
tx_packets: 3787
rx_bytes: 3295936
tx_bytes: 587243
rx_broadcast: 3
tx_broadcast: 63
rx_multicast: 23
tx_multicast: 89
rx_errors: 0
tx_errors: 0
tx_dropped: 0
multicast: 23
collisions: 0
rx_length_errors: 0
rx_over_errors: 0
rx_crc_errors: 0
rx_frame_errors: 0
rx_no_buffer_count: 0
rx_missed_errors: 0
tx_aborted_errors: 0
tx_carrier_errors: 0
tx_fifo_errors: 0
tx_heartbeat_errors: 0
tx_window_errors: 0
tx_abort_late_coll: 0
tx_deferred_ok: 0
tx_single_coll_ok: 0
tx_multi_coll_ok: 0
tx_timeout_count: 0
tx_restart_queue: 0
rx_long_length_errors: 0
rx_short_length_errors: 0
rx_align_errors: 0
tx_tcp_seg_good: 0
tx_tcp_seg_failed: 0
rx_flow_control_xon: 0
rx_flow_control_xoff: 0
tx_flow_control_xon: 0
tx_flow_control_xoff: 0
rx_long_byte_count: 3295936
rx_csum_offload_good: 3534
rx_csum_offload_errors: 0
rx_header_split: 0
alloc_rx_buff_failed: 0
tx_smbus: 0
rx_smbus: 0
dropped_smbus: 0
rx_dma_failed: 0
tx_dma_failed: 0
Konfiguration auslesen
# ethtool eth0 Settings for eth0: ## ab hier werden Geräteinformationen angezeigt Supported ports: [ TP ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Advertised pause frame use: No Advertised auto-negotiation: Yes ## ab hier werden Informationen der Gegenstelle (Switch/Router/PC) angezeigt Link partner advertised link modes: Not reported Link partner advertised pause frame use: No Link partner advertised auto-negotiation: No ## ab hier werden die momentanen Einstellungen der Karte angezeigt Speed: 100Mb/s Duplex: Full Port: Twisted Pair PHYAD: 1 Transceiver: internal Auto-negotiation: on MDI-X: off Supports Wake-on: pumbag Wake-on: g Current message level: 0x00000001 (1) Link detected: yes
Die Ausgabe teilt sich in Angaben zu den möglichen Einstellungen und Informationen zur Gegenstelle im oberen und der momentanen Konfiguration der Karte im unteren Abschnitt der Ausgabe.
Geschwindigkeit und Modus
Ändert die Übertragungsgeschwindigkeit in MBit/Sekunde und den Übertragungsmodus. Half bedeutet, dass Daten jeweils nur in eine Richtung übertragen werden. Full aktiviert gleichzeitiges Senden und Empfangen von Daten (Standard).
Report der Einstellungen:
Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full ... Speed: 100Mb/s Duplex: Full
Einstellung ändern:
# ethtool -s eth0 speed [10|100|1000] duplex [half|full]
Autonegotiation
Report der Einstellungen:
Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full ... Auto-negotiation: on
Einstellung ändern:
# ethtool -s eth0 autoneg [on|off]
Autoerkennung manuell wiederholen:
# ethtool -r eth0
Hinweis: Eine bestehende Verbindung kann dadurch unterbrochen werden!
Wake-On-Lan
Setzt mögliche WOL-Optionen.
- Nicht alle Karten und Treiber unterstützen diese Funktion.
Report der Einstellungen:
Supports Wake-on: pumbag Wake-on: g
Einstellung ändern:
# ethtool -s eth0 wol [p|u|m|b|a|g|s|d]
| Optionen | |
| Parameter | Beschreibung |
p
|
WOL bei Netzwerkaktivität |
u
|
WOL bei unicast Daten - Datenpakete sind an ein bestimmtes Gerät adressiert |
m
|
WOL bei multicast Daten - Datenpakete sind nicht an ein bestimmtes Gerät adressiert |
b
|
WOL bei Broadcast Daten - Datenpakete werden von einem Punkt an alle Teilnehmer im Netzwerk gesendet |
a
|
WOL gemäß ARP-Protokoll |
g
|
WOL bei Magic Packet |
s
|
aktiviert ein Kennwort für Magic-Packet |
d
|
WOL abgeschaltet - alle vorangehenden Optionen werden gelöscht. |
Kennwort und Modus für WOL festlegen, sofern unterstützt:
# ethtool -s eth0 wol s # ethtool -s eth0 sopass xx:yy:zz:aa:bb:cc
Das Kennwort muss als sechs Byte große Zeichenkette im hex-Format (xx:yy:zz:aa:bb:cc) angegeben werden.
Zusätzliche Informationen
Folgender Befehl liefert Informationen zum verwendeten Treibermodul, zur Firmware und PCI Bus-Nummer:
Abfrage:
ethtool -i eth0
Beispielausgabe:
driver: e1000e version: 1.0.2-k2 firmware-version: 1.1-2 bus-info: 0000:00:19.0
MDI-X
MDI-X (Medium Dependent Interface/ X = Crossover) bezeichnet ein Verfahren zur automatischen Anschlusserkennung und des verwendeten Kabeltyps.
- So können bei einer Direktverbindung zweier Rechner normale Patchkabel oder gekreuzte Kabel (Crosslink-Kabel) verwendet werden.
- Alle Gigabit Ethernet-Karten und einige Fast-Ethernet-Karten unterstützen diese Funktion.
- Einstellungen können hierzu nicht geändert werden.
- Wird diese Option bei Abfrage der Konfiguration nicht angezeigt, unterstützt die verwendete Karte diese Funktion sehr wahrscheinlich nicht.
- Siehe dazu auch PC-Direktverbindung per Netzwerk-Kabel.
Erweiterte Einstellungen
Adaptererkennung
Zur besseren Erkennung einzelner Karten und des zugehörigen Anschlusses kann man die Verbindungs-LED, sofern vorhanden, für eine vorgegebene Zeit blinken lassen.
- Das ist z. B. in Serversystemen mit mehreren Netzwerkkarten hilfreich.
# ethtool -p eth0 10
Hier blinkt die Anzeige für zehn Sekunden.
Größe der Datenpakete
Abfrage:
# ethtool -g eth0
Ring parameters for eth0: Pre-set maximums: RX: 4096 RX Mini: 0 RX Jumbo: 0 TX: 4096 Current hardware settings: RX: 256 RX Mini: 0 RX Jumbo: 0 TX: 256
Ändern entsprechender Parameter:
# ethtool -G ethX [rx N] [rx-mini N] [rx-jumbo N] [tx N]
Hinweis: rx-jumbo / Jumboframes gibt es nur bei Gigabit Netzwerkkarten.
Anschluss-Port umschalten
Sofern die Karte über verschiedenen Anschlüsse verfügt, lassen sich diese umschalten.
- Standard ist TP (Twisted-Pair).
Report der Einstellung:
Supported ports: [ TP ] ...
Ändern entsprechender Werte:
# ethtool -s eth0 port [tp|aui|bnc|mii]
Begrifferkärung:
- Twisted_Pair - tp (Standard)
- Attachment Unit Interface - aui
- BNC-Steckverbindungen - bnc
- Media Independent Interface - mii
Transceiver umschalten
Transceiver = Kombination aus Sender und Empfänger.
... Transceiver: internal
Ändern entsprechender Werte:
# ethtool -s eth0 xcvr [internal|external]
Die Funktion ist normalerweise wirkungslos.
Paketmanagement
Erweiterte Einstellungen zur Verarbeitung von Netzwerkpaketen und zur Leistungssteigerung wie TCP-segmentation-offload, UFO (udp fragmentation offload), GSO (generic segmentation offload), GRO (generic receive offload) LRO (large receive offload) Speicherdirektzugriff und Busmastering (sg / scatter-gather):
Abfrage:
# ethtool -k eth0
Offload parameters for eth0: rx-checksumming: on tx-checksumming: on scatter-gather: on tcp-segmentation-offload: off udp-fragmentation-offload: off generic-segmentation-offload: on generic-receive-offload: off large-receive-offload: off
Entsprechende Optionen können wie folgt geändert werden:
# ethtool -K eth0 [rx on|off] [tx on|off] [sg on|off] [tso on|off] [ufo on|off] [gso on|off] [lro on|off]
Statusregister
Abfrage:
# ethtool -d eth0 raw off
MAC Registers
-------------
0x00000: CTRL (Device control register) 0x18100240
Endian mode (buffers): little
Link reset: normal
Set link up: 1
Invert Loss-Of-Signal: no
Receive flow control: enabled
Transmit flow control: enabled
VLAN mode: disabled
Auto speed detect: disabled
Speed select: 1000Mb/s
Force speed: no
Force duplex: no
0x00008: STATUS (Device status register) 0x0008064B
Duplex: full
Link up: link config
TBI mode: disabled
Link speed: 100Mb/s
Bus type: PCI
Bus speed: 33MHz
Bus width: 32-bit
0x00100: RCTL (Receive control register) 0x04008002
Receiver: enabled
Store bad packets: disabled
Unicast promiscuous: disabled
Multicast promiscuous: disabled
Long packet: disabled
Descriptor minimum threshold size: 1/2
Broadcast accept mode: accept
VLAN filter: disabled
Canonical form indicator: disabled
Discard pause frames: filtered
Pass MAC control frames: don't pass
Receive buffer size: 2048
0x02808: RDLEN (Receive desc length) 0x00001000
0x02810: RDH (Receive desc head) 0x00000065
0x02818: RDT (Receive desc tail) 0x00000063
0x02820: RDTR (Receive delay timer) 0x00000000
0x00400: TCTL (Transmit ctrl register) 0x3103F0FA
Transmitter: enabled
Pad short packets: enabled
Software XOFF Transmission: disabled
Re-transmit on late collision: enabled
0x03808: TDLEN (Transmit desc length) 0x00001000
0x03810: TDH (Transmit desc head) 0x000000D8
0x03818: TDT (Transmit desc tail) 0x000000D8
0x03820: TIDV (Transmit delay timer) 0x00000008
PHY type: unknown
EEProm auslesen
Abfrage:
# ethtool -e eth0 raw off
Offset Values ------ ------ 0x0000 00 24 21 0e 8f 4a 00 08 ff ff 12 10 ff ff ff ff 0x0010 ff ff ff ff c3 10 2c 50 62 14 c0 10 86 80 00 00 0x0020 02 04 00 00 00 00 85 86 20 00 00 00 00 00 07 00 0x0030 84 06 40 2b 43 00 04 00 ad ba ad ba be 10 bf 10 0x0040 ad ba 4c 29 bd 10 ad ba 00 00 00 00 00 00 00 00 0x0050 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0060 00 01 00 40 32 12 07 40 ff ff ff ff ff ff ff ff ...
Im ersten Block befindet sich z. B.
- die MAC-Adresse der Karte.
Ändern entsprechender Werte:
ethtool -E eth0 [magic N] [offset N] [value N]
ethtool im Einsatz
Zur Anzeige der aktuellen Parameter wird ethtool mit dem entsprechenden Interface als Parameter aufgerufen. Hier die Ausgabe für das Interface eth0:
~ $ ethtool eth0
Settings for eth0:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Advertised auto-negotiation: Yes
Speed: 10Mb/s
Duplex: Half
Port: MII
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
Current message level: 0x000020c1 (8385)
Link detected: no
Diese Netzwerkkarte unterstützt 10 und 100 MBit/s jeweils mit Halb- und Vollduplex. Die letzte Zeile der Ausgabe zeigt uns an, dass kein Link erkannt wurde. Zum Vergleich hier ein Aufruf von ethtool bei aktiver Verbindung zu einem Switch der Autonegotiation unterstützt:
~ $ ethtool eth0
Settings for eth0:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Advertised auto-negotiation: Yes
Speed: 100Mb/s
Duplex: Full
Port: MII
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
Current message level: 0x000020c1 (8385)
Link detected: yes
Mit ethtool ist es auch möglich, Einstellungen der Netzwerkkarte zu verändern. Das folgende Kommando stellt das Interface eth0 auf 10 MBit/s und Halbduplex ein.
~ $ ethtool -s eth0 speed 10 duplex half [mirko]
Für Speed sind die Parameter 10, 100 und 1000 erlaubt. Der Duplexmode kann auf "half" oder "full" eingestellt werden. Autonegotiation wird mit dem Paramter "autoneg on" angeschaltet und mit "autoneg off" abgeschaltet.
~ $ ethtool -s eth0 autoneg on [mirko]
Neuere Netzwerkkarten haben mitunter die Möglichkeit, eine LED manuell blinkne zu lassen. Das ist zum Identifizieren einer Karte in komplexen Umgebungen sehr hilfreich. Ethtool startet man dazu mit dem Parameter "-p".
~ $ ethtool -p eth1 [mirko]
Für Netzwerkinterfaces die WakeOnLAN (WOL) beherrschen, bietet ethtool auch einige Möglichkeiten der Konfiguration. Der Benutzer kann festlegen welche Art von Frame ein Aufwachen auslösen soll und ein Kennwort für Wake On LAN festlegen.
wol p|u|m|b|a|g|s|d...
Set Wake-on-LAN options. Not all devices support this. The
argument to this option is a string of characters specifying
which options to enable.
p Wake on phy activity
u Wake on unicast messages
m Wake on multicast messages
b Wake on broadcast messages
a Wake on ARP
g Wake on MagicPacket(tm)
s Enable SecureOn(tm) password for MagicPacket(tm)
d Disable (wake on nothing). This option clears all previous
options.
sopass xx:yy:zz:aa:bb:cc
Set the SecureOn(tm) password. The argument to this option must
be 6 bytes in ethernet MAC hex format (xx:yy:zz:aa:bb:cc).
Leider arbeiten nicht alle Treiber mit ethtool zusammen.
Weiterführende Informationen finden Sie unter folgenden Link:
- Details zum Duplex Mismatch [lokal]
- Netzwerkdiagnose mit mii-diag [lokal]
- Manpage von ethtool [lokal]
- gkernel auf sourceforge [extern]
Sicherheit
Dokumentation
RFC
Man-Pages
Info-Pages
Siehe auch
Links
Projekt
Weblinks
Manpage
NAME
ethtool - query or control network driver and hardware settings
SYNOPSIS
ethtool devname
ethtool -h|--help
ethtool --version
ethtool [--debug N] args
ethtool [--json] args
ethtool [-I | --include-statistics] args
ethtool --monitor [ command ] [ devname ]
ethtool -a|--show-pause devname
ethtool -A|--pause devname [autoneg on|off] [rx on|off] [tx on|off]
ethtool -c|--show-coalesce devname
ethtool -C|--coalesce devname [adaptive-rx on|off] [adaptive-tx on|off] [rx-usecs N] [rx-frames N] [rx-usecs-irq N] [rx-frames-irq N] [tx-usecs N] [tx-frames N]
[tx-usecs-irq N] [tx-frames-irq N] [stats-block-usecs N] [pkt-rate-low N] [rx-usecs-low N] [rx-frames-low N] [tx-usecs-low N] [tx-frames-low N]
[pkt-rate-high N] [rx-usecs-high N] [rx-frames-high N] [tx-usecs-high N] [tx-frames-high N] [sample-interval N] [cqe-mode-rx on|off] [cqe-mode-tx on|off]
ethtool -g|--show-ring devname
ethtool -G|--set-ring devname [rx N] [rx-mini N] [rx-jumbo N] [tx N] [rx-buf-len N]
ethtool -i|--driver devname
ethtool -d|--register-dump devname [raw on|off] [hex on|off] [file name]
ethtool -e|--eeprom-dump devname [raw on|off] [offset N] [length N]
ethtool -E|--change-eeprom devname [magic N] [offset N] [length N] [value N]
ethtool -k|--show-features|--show-offload devname
ethtool -K|--features|--offload devname feature on|off ...
ethtool -p|--identify devname [N]
ethtool -P|--show-permaddr devname
ethtool -r|--negotiate devname
ethtool -S|--statistics devname [--all-groups|--groups [eth-phy] [eth-mac] [eth-ctrl] ]
ethtool --phy-statistics devname
ethtool -t|--test devname [offline|online|external_lb]
ethtool -s devname [speed N] [lanes N] [duplex half|full] [port tp|aui|bnc|mii] [mdix auto|on|off] [autoneg on|off] [advertise N[/M] | advertise mode on|off ...]
[phyad N] [xcvr internal|external] [wol N[/M] | wol p|u|m|b|a|g|s|f|d...] [sopass xx:yy:zz:aa:bb:cc] [master-slave preferred-master|preferred-slave|forced-
master|forced-slave] [msglvl N[/M] | msglvl type on|off ...]
ethtool -n|-u|--show-nfc|--show-ntuple devname [ rx-flow-hash tcp4|udp4|ah4|esp4|sctp4|tcp6|udp6|ah6|esp6|sctp6 |
rule N ]
ethtool -N|-U|--config-nfc|--config-ntuple devname rx-flow-hash tcp4|udp4|ah4|esp4|sctp4|tcp6|udp6|ah6|esp6|sctp6 m|v|t|s|d|f|n|r... |
flow-type ether|ip4|tcp4|udp4|sctp4|ah4|esp4|ip6|tcp6|udp6|ah6|esp6|sctp6 [src xx:yy:zz:aa:bb:cc [m xx:yy:zz:aa:bb:cc]]
[dst xx:yy:zz:aa:bb:cc [m xx:yy:zz:aa:bb:cc]] [proto N [m N]] [src-ip ip-address [m ip-address]] [dst-ip ip-address [m ip-address]] [tos N [m N]]
[tclass N [m N]] [l4proto N [m N]] [src-port N [m N]] [dst-port N [m N]] [spi N [m N]] [l4data N [m N]] [vlan-etype N [m N]] [vlan N [m N]] [user-def N [m N]]
[dst-mac xx:yy:zz:aa:bb:cc [m xx:yy:zz:aa:bb:cc]] [action N] [context N] [loc N] |
delete N
ethtool -w|--get-dump devname [data filename]
ethtool -W|--set-dump devname N
ethtool -T|--show-time-stamping devname
ethtool -x|--show-rxfh-indir|--show-rxfh devname
ethtool -X|--set-rxfh-indir|--rxfh devname [hkey xx:yy:zz:aa:bb:cc:...] [start N] [ equal N | weight W0 W1 ... | default ] [hfunc FUNC] [context CTX | new] [delete]
ethtool -f|--flash devname file [N]
ethtool -l|--show-channels devname
ethtool -L|--set-channels devname [rx N] [tx N] [other N] [combined N]
ethtool -m|--dump-module-eeprom|--module-info devname [raw on|off] [hex on|off] [offset N] [length N] [page N] [bank N] [i2c N]
ethtool --show-priv-flags devname
ethtool --set-priv-flags devname flag on|off ...
ethtool --show-eee devname
ethtool --set-eee devname [eee on|off] [tx-lpi on|off] [tx-timer N] [advertise N]
ethtool --set-phy-tunable devname [ downshift on|off [count N] ] [ fast-link-down on|off [msecs N] ] [ energy-detect-power-down on|off [msecs N] ]
ethtool --get-phy-tunable devname [downshift] [fast-link-down] [energy-detect-power-down]
ethtool --get-tunable devname [rx-copybreak] [tx-copybreak] [tx-buf-size] [pfc-prevention-tout]
ethtool --set-tunable devname [rx-copybreak N] [tx-copybreak N] [tx-buf-size N] [pfc-prevention-tout N]
ethtool --reset devname [flags N] [mgmt] [mgmt-shared] [irq] [irq-shared] [dma] [dma-shared] [filter] [filter-shared] [offload] [offload-shared] [mac] [mac-shared]
[phy] [phy-shared] [ram] [ram-shared] [ap] [ap-shared] [dedicated] [all]
ethtool --show-fec devname
ethtool --set-fec devname encoding auto|off|rs|baser|llrs [...]
ethtool -Q|--per-queue devname [queue_mask %x] sub_command ...
.
ethtool --cable-test devname
ethtool --cable-test-tdr devname [first N] [last N] [step N] [pair N]
ethtool --show-tunnels devname
ethtool --show-module devname
ethtool --set-module devname [power-mode-policy high|auto]
DESCRIPTION
ethtool is used to query and control network device driver and hardware settings, particularly for wired Ethernet devices.
devname is the name of the network device on which ethtool should operate.
OPTIONS
ethtool with a single argument specifying the device name prints current settings of the specified device.
-h --help
Shows a short help message.
--version
Shows the ethtool version number.
--debug N
Turns on debugging messages. Argument is interpreted as a mask:
0x01 Parser information
--json Output results in JavaScript Object Notation (JSON). Only a subset of options support this. Those which do not will continue to output plain text in the pres‐
ence of this option.
-I --include-statistics
Include command-related statistics in the output. This option allows displaying relevant device statistics for selected get commands.
-a --show-pause
Queries the specified Ethernet device for pause parameter information.
-A --pause
Changes the pause parameters of the specified Ethernet device.
autoneg on|off
Specifies whether pause autonegotiation should be enabled.
rx on|off
Specifies whether RX pause should be enabled.
tx on|off
Specifies whether TX pause should be enabled.
-c --show-coalesce
Queries the specified network device for coalescing information.
-C --coalesce
Changes the coalescing settings of the specified network device.
-g --show-ring
Queries the specified network device for rx/tx ring parameter information.
-G --set-ring
Changes the rx/tx ring parameters of the specified network device.
rx N Changes the number of ring entries for the Rx ring.
rx-mini N
Changes the number of ring entries for the Rx Mini ring.
rx-jumbo N
Changes the number of ring entries for the Rx Jumbo ring.
tx N Changes the number of ring entries for the Tx ring.
rx-buf-len N
Changes the size of a buffer in the Rx ring.
-i --driver
Queries the specified network device for associated driver information.
-d --register-dump
Retrieves and prints a register dump for the specified network device. The register format for some devices is known and decoded others are printed in hex.
When raw is enabled, then ethtool dumps the raw register data to stdout. If file is specified, then use contents of previous raw register dump, rather than
reading from the device.
-e --eeprom-dump
Retrieves and prints an EEPROM dump for the specified network device. When raw is enabled, then it dumps the raw EEPROM data to stdout. The length and offset
parameters allow dumping certain portions of the EEPROM. Default is to dump the entire EEPROM.
raw on|off
offset N
length N
-E --change-eeprom
If value is specified, changes EEPROM byte for the specified network device. offset and value specify which byte and it's new value. If value is not specified,
stdin is read and written to the EEPROM. The length and offset parameters allow writing to certain portions of the EEPROM. Because of the persistent nature of
writing to the EEPROM, a device-specific magic key must be specified to prevent the accidental writing to the EEPROM.
-k --show-features --show-offload
Queries the specified network device for the state of protocol offload and other features.
-K --features --offload
Changes the offload parameters and other features of the specified network device. The following feature names are built-in and others may be defined by the
kernel.
rx on|off
Specifies whether RX checksumming should be enabled.
tx on|off
Specifies whether TX checksumming should be enabled.
sg on|off
Specifies whether scatter-gather should be enabled.
tso on|off
Specifies whether TCP segmentation offload should be enabled.
ufo on|off
Specifies whether UDP fragmentation offload should be enabled
gso on|off
Specifies whether generic segmentation offload should be enabled
gro on|off
Specifies whether generic receive offload should be enabled
lro on|off
Specifies whether large receive offload should be enabled
rxvlan on|off
Specifies whether RX VLAN acceleration should be enabled
txvlan on|off
Specifies whether TX VLAN acceleration should be enabled
ntuple on|off
Specifies whether Rx ntuple filters and actions should be enabled
rxhash on|off
Specifies whether receive hashing offload should be enabled
-p --identify
Initiates adapter-specific action intended to enable an operator to easily identify the adapter by sight. Typically this involves blinking one or more LEDs on
the specific network port.
[ N] Length of time to perform phys-id, in seconds.
-P --show-permaddr
Queries the specified network device for permanent hardware address.
-r --negotiate
Restarts auto-negotiation on the specified Ethernet device, if auto-negotiation is enabled.
-S --statistics
Queries the specified network device for standard (IEEE, IETF, etc.), or NIC- and driver-specific statistics. NIC- and driver-specific statistics are requested
when no group of statistics is specified.
NIC- and driver-specific statistics and standard statistics are independent, devices may implement either, both or none. There is little commonality between
naming of NIC- and driver-specific statistics across vendors.
--all-groups
--groups [eth-phy] [eth-mac] [eth-ctrl] [rmon]
Request groups of standard device statistics.
--phy-statistics
Queries the specified network device for PHY specific statistics.
-t --test
Executes adapter selftest on the specified network device. Possible test modes are:
offline
Perform full set of tests, possibly interrupting normal operation during the tests,
online Perform limited set of tests, not interrupting normal operation,
external_lb
Perform full set of tests, as for offline, and additionally an external-loopback test.
-s --change
Allows changing some or all settings of the specified network device. All following options only apply if -s was specified.
speed N
Set speed in Mb/s. ethtool with just the device name as an argument will show you the supported device speeds.
lanes N
Set number of lanes.
duplex half|full
Sets full or half duplex mode.
port tp|aui|bnc|mii
Selects device port.
master-slave preferred-master|preferred-slave|forced-master|forced-slave
Configure MASTER/SLAVE role of the PHY. When the PHY is configured as MASTER, the PMA Transmit function shall source TX_TCLK from a local clock source. When
configured as SLAVE, the PMA Transmit function shall source TX_TCLK from the clock recovered from data stream provided by MASTER. Not all devices support
this.
preferred-master Prefer MASTER role on autonegotiation
preferred-slave Prefer SLAVE role on autonegotiation
forced-master Force the PHY in MASTER role. Can be used without autonegotiation
forced-slave Force the PHY in SLAVE role. Can be used without autonegotiation
mdix auto|on|off
Selects MDI-X mode for port. May be used to override the automatic detection feature of most adapters. An argument of auto means automatic detection of MDI
status, on forces MDI-X (crossover) mode, while off means MDI (straight through) mode. The driver should guarantee that this command takes effect immedi‐
ately, and if necessary may reset the link to cause the change to take effect.
autoneg on|off
Specifies whether autonegotiation should be enabled. Autonegotiation is enabled by default, but in some network devices may have trouble with it, so you can
disable it if really necessary.
advertise N
Sets the speed and duplex advertised by autonegotiation. The argument is a hexadecimal value using one or a combination of the following values:
0x001 10baseT Half
0x002 10baseT Full
0x004 100baseT Half
0x008 100baseT Full
0x80000000000000000 100baseT1 Full
0x40000000000000000000000 100baseFX Half
0x80000000000000000000000 100baseFX Full
0x010 1000baseT Half (not supported by IEEE standards)
0x020 1000baseT Full
0x20000 1000baseKX Full
0x20000000000 1000baseX Full
0x100000000000000000 1000baseT1 Full
0x8000 2500baseX Full (not supported by IEEE standards)
0x800000000000 2500baseT Full
0x1000000000000 5000baseT Full
0x1000 10000baseT Full
0x40000 10000baseKX4 Full
0x80000 10000baseKR Full
0x100000 10000baseR_FEC
0x40000000000 10000baseCR Full
0x80000000000 10000baseSR Full
0x100000000000 10000baseLR Full
0x200000000000 10000baseLRM Full
0x400000000000 10000baseER Full
0x200000 20000baseMLD2 Full (not supported by IEEE standards)
0x400000 20000baseKR2 Full (not supported by IEEE standards)
0x80000000 25000baseCR Full
0x100000000 25000baseKR Full
0x200000000 25000baseSR Full
0x800000 40000baseKR4 Full
0x1000000 40000baseCR4 Full
0x2000000 40000baseSR4 Full
0x4000000 40000baseLR4 Full
0x400000000 50000baseCR2 Full
0x800000000 50000baseKR2 Full
0x10000000000 50000baseSR2 Full
0x10000000000000 50000baseKR Full
0x20000000000000 50000baseSR Full
0x40000000000000 50000baseCR Full
0x80000000000000 50000baseLR_ER_FR Full
0x100000000000000 50000baseDR Full
0x8000000 56000baseKR4 Full
0x10000000 56000baseCR4 Full
0x20000000 56000baseSR4 Full
0x40000000 56000baseLR4 Full
0x1000000000 100000baseKR4 Full
0x2000000000 100000baseSR4 Full
0x4000000000 100000baseCR4 Full
0x8000000000 100000baseLR4_ER4 Full
0x200000000000000 100000baseKR2 Full
0x400000000000000 100000baseSR2 Full
0x800000000000000 100000baseCR2 Full
0x1000000000000000 100000baseLR2_ER2_FR2 Full
0x2000000000000000 100000baseDR2 Full
0x8000000000000000000 100000baseKR Full
0x10000000000000000000 100000baseSR Full
0x20000000000000000000 100000baseLR_ER_FR Full
0x40000000000000000000 100000baseCR Full
0x80000000000000000000 100000baseDR Full
0x4000000000000000 200000baseKR4 Full
0x8000000000000000 200000baseSR4 Full
0x10000000000000000 200000baseLR4_ER4_FR4 Full
0x20000000000000000 200000baseDR4 Full
0x40000000000000000 200000baseCR4 Full
0x100000000000000000000 200000baseKR2 Full
0x200000000000000000000 200000baseSR2 Full
0x400000000000000000000 200000baseLR2_ER2_FR2 Full
0x800000000000000000000 200000baseDR2 Full
0x1000000000000000000000 200000baseCR2 Full
0x200000000000000000 400000baseKR8 Full
0x400000000000000000 400000baseSR8 Full
0x800000000000000000 400000baseLR8_ER8_FR8 Full
0x1000000000000000000 400000baseDR8 Full
0x2000000000000000000 400000baseCR8 Full
0x2000000000000000000000 400000baseKR4 Full
0x4000000000000000000000 400000baseSR4 Full
0x8000000000000000000000 400000baseLR4_ER4_FR4 Full
0x10000000000000000000000 400000baseDR4 Full
0x20000000000000000000000 400000baseCR4 Full
phyad N
PHY address.
xcvr internal|external
Selects transceiver type. Currently only internal and external can be specified, in the future further types might be added.
wol p|u|m|b|a|g|s|f|d...
Sets Wake-on-LAN options. Not all devices support this. The argument to this option is a string of characters specifying which options to enable.
p Wake on PHY activity
u Wake on unicast messages
m Wake on multicast messages
b Wake on broadcast messages
a Wake on ARP
g Wake on MagicPacket™
s Enable SecureOn™ password for MagicPacket™
f Wake on filter(s)
d Disable (wake on nothing). This option clears all previ‐
ous options.
sopass xx:yy:zz:aa:bb:cc
Sets the SecureOn™ password. The argument to this option must be 6 bytes in Ethernet MAC hex format (xx:yy:zz:aa:bb:cc).
msglvl N
msglvl type on|off ...
Sets the driver message type flags by name or number. type names the type of message to enable or disable; N specifies the new flags numerically. The de‐
fined type names and numbers are:
drv 0x0001 General driver status
probe 0x0002 Hardware probing
link 0x0004 Link state
timer 0x0008 Periodic status check
ifdown 0x0010 Interface being brought down
ifup 0x0020 Interface being brought up
rx_err 0x0040 Receive error
tx_err 0x0080 Transmit error
tx_queued 0x0100 Transmit queueing
intr 0x0200 Interrupt handling
tx_done 0x0400 Transmit completion
rx_status 0x0800 Receive completion
pktdata 0x1000 Packet contents
hw 0x2000 Hardware status
wol 0x4000 Wake-on-LAN status
The precise meanings of these type flags differ between drivers.
-n -u --show-nfc --show-ntuple
Retrieves receive network flow classification options or rules.
rx-flow-hash tcp4|udp4|ah4|esp4|sctp4|tcp6|udp6|ah6|esp6|sctp6
Retrieves the hash options for the specified flow type.
tcp4 TCP over IPv4
udp4 UDP over IPv4
ah4 IPSEC AH over IPv4
esp4 IPSEC ESP over IPv4
sctp4 SCTP over IPv4
tcp6 TCP over IPv6
udp6 UDP over IPv6
ah6 IPSEC AH over IPv6
esp6 IPSEC ESP over IPv6
sctp6 SCTP over IPv6
rule N Retrieves the RX classification rule with the given ID.
-N -U --config-nfc --config-ntuple
Configures receive network flow classification options or rules.
rx-flow-hash tcp4|udp4|ah4|esp4|sctp4|tcp6|udp6|ah6|esp6|sctp6m|v|t|s|d|f|n|r...
Configures the hash options for the specified flow type.
m Hash on the Layer 2 destination address of the rx packet.
v Hash on the VLAN tag of the rx packet.
t Hash on the Layer 3 protocol field of the rx packet.
s Hash on the IP source address of the rx packet.
d Hash on the IP destination address of the rx packet.
f Hash on bytes 0 and 1 of the Layer 4 header of the rx packet.
n Hash on bytes 2 and 3 of the Layer 4 header of the rx packet.
r Discard all packets of this flow type. When this option is
set, all other options are ignored.
flow-type ether|ip4|tcp4|udp4|sctp4|ah4|esp4|ip6|tcp6|udp6|ah6|esp6|sctp6
Inserts or updates a classification rule for the specified flow type.
ether Ethernet
ip4 Raw IPv4
tcp4 TCP over IPv4
udp4 UDP over IPv4
sctp4 SCTP over IPv4
ah4 IPSEC AH over IPv4
esp4 IPSEC ESP over IPv4
ip6 Raw IPv6
tcp6 TCP over IPv6
udp6 UDP over IPv6
sctp6 SCTP over IPv6
ah6 IPSEC AH over IPv6
esp6 IPSEC ESP over IPv6
For all fields that allow both a value and a mask to be specified, the mask may be specified immediately after the value using the m keyword, or separately using
the field name keyword with -mask appended, e.g. src-mask.
src xx:yy:zz:aa:bb:cc [m xx:yy:zz:aa:bb:cc]
Includes the source MAC address, specified as 6 bytes in hexadecimal separated by colons, along with an optional mask. Valid only for flow-type ether.
dst xx:yy:zz:aa:bb:cc [m xx:yy:zz:aa:bb:cc]
Includes the destination MAC address, specified as 6 bytes in hexadecimal separated by colons, along with an optional mask. Valid only for flow-type ether.
proto N [m N]
Includes the Ethernet protocol number (ethertype) and an optional mask. Valid only for flow-type ether.
src-ip ip-address [m ip-address]
Specify the source IP address of the incoming packet to match along with an optional mask. Valid for all IP based flow-types.
dst-ip ip-address [m ip-address]
Specify the destination IP address of the incoming packet to match along with an optional mask. Valid for all IP based flow-types.
tos N [m N]
Specify the value of the Type of Service field in the incoming packet to match along with an optional mask. Applies to all IPv4 based flow-types.
tclass N [m N]
Specify the value of the Traffic Class field in the incoming packet to match along with an optional mask. Applies to all IPv6 based flow-types.
l4proto N [m N]
Includes the layer 4 protocol number and optional mask. Valid only for flow-types ip4 and ip6.
src-port N [m N]
Specify the value of the source port field (applicable to TCP/UDP packets) in the incoming packet to match along with an optional mask. Valid for flow-
types ip4, tcp4, udp4, and sctp4 and their IPv6 equivalents.
dst-port N [m N]
Specify the value of the destination port field (applicable to TCP/UDP packets)in the incoming packet to match along with an optional mask. Valid for flow-
types ip4, tcp4, udp4, and sctp4 and their IPv6 equivalents.
spi N [m N]
Specify the value of the security parameter index field (applicable to AH/ESP packets)in the incoming packet to match along with an optional mask. Valid
for flow-types ip4, ah4, and esp4 and their IPv6 equivalents.
l4data N [m N]
Specify the value of the first 4 Bytes of Layer 4 in the incoming packet to match along with an optional mask. Valid for ip4 and ip6 flow-types.
vlan-etype N [m N]
Includes the VLAN tag Ethertype and an optional mask.
vlan N [m N]
Includes the VLAN tag and an optional mask.
user-def N [m N]
Includes 64-bits of user-specific data and an optional mask.
dst-mac xx:yy:zz:aa:bb:cc [m xx:yy:zz:aa:bb:cc]
Includes the destination MAC address, specified as 6 bytes in hexadecimal separated by colons, along with an optional mask. Valid for all IP based flow-
types.
action N
Specifies the Rx queue to send packets to, or some other action.
-1 Drop the matched flow
-2 Use the matched flow as a Wake-on-LAN filter
0 or higher Rx queue to route the flow
context N
Specifies the RSS context to spread packets over multiple queues; either 0 for the default RSS context, or a value returned by ethtool -X ... context new.
vf N Specifies the Virtual Function the filter applies to. Not compatible with action.
queue N
Specifies the Rx queue to send packets to. Not compatible with action.
loc N Specify the location/ID to insert the rule. This will overwrite any rule present in that location and will not go through any of the rule ordering process.
delete N
Deletes the RX classification rule with the given ID.
-w --get-dump
Retrieves and prints firmware dump for the specified network device. By default, it prints out the dump flag, version and length of the dump data. When data
is indicated, then ethtool fetches the dump data and directs it to a file.
-W --set-dump
Sets the dump flag for the device.
-T --show-time-stamping
Show the device's time stamping capabilities and associated PTP hardware clock.
-x --show-rxfh-indir --show-rxfh
Retrieves the receive flow hash indirection table and/or RSS hash key.
-X --set-rxfh-indir --rxfh
Configures the receive flow hash indirection table and/or RSS hash key.
hkey Sets RSS hash key of the specified network device. RSS hash key should be of device supported length. Hash key format must be in xx:yy:zz:aa:bb:cc format
meaning both the nibbles of a byte should be mentioned even if a nibble is zero.
hfunc Sets RSS hash function of the specified network device. List of RSS hash functions which kernel supports is shown as a part of the --show-rxfh command out‐
put.
start N
For the equal and weight options, sets the starting receive queue for spreading flows to N.
equal N
Sets the receive flow hash indirection table to spread flows evenly between the first N receive queues.
weight W0 W1 ...
Sets the receive flow hash indirection table to spread flows between receive queues according to the given weights. The sum of the weights must be non-zero
and must not exceed the size of the indirection table.
default
Sets the receive flow hash indirection table to its default value.
context CTX | new
Specifies an RSS context to act on; either new to allocate a new RSS context, or CTX, a value returned by a previous ... context new.
delete Delete the specified RSS context. May only be used in conjunction with context and a non-zero CTX value.
-f --flash
Write a firmware image to flash or other non-volatile memory on the device.
file Specifies the filename of the firmware image. The firmware must first be installed in one of the directories where the kernel firmware loader or firmware
agent will look, such as /lib/firmware.
N If the device stores multiple firmware images in separate regions of non-volatile memory, this parameter may be used to specify which region is to be writ‐
ten. The default is 0, requesting that all regions are written. All other values are driver-dependent.
-l --show-channels
Queries the specified network device for the numbers of channels it has. A channel is an IRQ and the set of queues that can trigger that IRQ.
-L --set-channels
Changes the numbers of channels of the specified network device.
rx N Changes the number of channels with only receive queues.
tx N Changes the number of channels with only transmit queues.
other N
Changes the number of channels used only for other purposes e.g. link interrupts or SR-IOV co-ordination.
combined N
Changes the number of multi-purpose channels.
-m --dump-module-eeprom --module-info
Retrieves and if possible decodes the EEPROM from plugin modules, e.g SFP+, QSFP. If the driver and module support it, the optical diagnostic information is
also read and decoded. When either one of page, bank or i2c parameters is specified, dumps only of a single page or its portion is allowed. In such a case off‐
set and length parameters are treated relatively to EEPROM page boundaries.
--show-priv-flags
Queries the specified network device for its private flags. The names and meanings of private flags (if any) are defined by each network device driver.
--set-priv-flags
Sets the device's private flags as specified.
flag on|off Sets the state of the named private flag.
--show-eee
Queries the specified network device for its support of Energy-Efficient Ethernet (according to the IEEE 802.3az specifications)
--set-eee
Sets the device EEE behaviour.
eee on|off
Enables/disables the device support of EEE.
tx-lpi on|off
Determines whether the device should assert its Tx LPI.
advertise N
Sets the speeds for which the device should advertise EEE capabilities. Values are as for --change advertise
tx-timer N
Sets the amount of time the device should stay in idle mode prior to asserting its Tx LPI (in microseconds). This has meaning only when Tx LPI is enabled.
--set-phy-tunable
Sets the PHY tunable parameters.
downshift on|off
Specifies whether downshift should be enabled.
count N
Sets the PHY downshift re-tries count.
fast-link-down on|off
Specifies whether Fast Link Down should be enabled and time until link down (if supported).
msecs N
Sets the period after which the link is reported as down. Note that the PHY may choose
the closest supported value. Only on reading back the tunable do you get the actual value.
energy-detect-power-down on|off
Specifies whether Energy Detect Power Down (EDPD) should be enabled (if supported). This will put the RX and TX circuit blocks into a low power mode, and
the PHY will wake up periodically to send link pulses to avoid any lock-up situation with a peer PHY that may also have EDPD enabled. By default, this set‐
ting will also enable the periodic transmission of TX pulses.
msecs N
Some PHYs support configuration of the wake-up interval to send TX pulses.
This setting allows the control of this interval, and 0 disables TX pulses
if the PHY supports this. Disabling TX pulses can create a lock-up situation
where neither of the PHYs wakes the other one. If unspecified the default
value (in milliseconds) will be used by the PHY.
--get-phy-tunable
Gets the PHY tunable parameters.
downshift
For operation in cabling environments that are incompatible with 1000BASE-T, PHY device provides an automatic link speed downshift operation. Link speed
downshift after N failed 1000BASE-T auto-negotiation attempts. Downshift is useful where cable does not have the 4 pairs instance.
Gets the PHY downshift count/status.
fast-link-down
Depending on the mode it may take 0.5s - 1s until a broken link is reported as down. In certain use cases a link-down event needs to be reported as soon as
possible. Some PHYs support a Fast Link Down Feature and may allow configuration of the delay before a broken link is reported as being down.
Gets the PHY Fast Link Down status / period.
energy-detect-power-down
Gets the current configured setting for Energy Detect Power Down (if supported).
--get-tunable
Get the tunable parameters.
rx-copybreak
Get the current rx copybreak value in bytes.
tx-copybreak
Get the current tx copybreak value in bytes.
tx-buf-size
Get the current tx copybreak buffer size in bytes.
pfc-prevention-tout
Get the current pfc prevention timeout value in msecs.
--set-tunable
Set driver's tunable parameters.
rx-copybreak N
Set the rx copybreak value in bytes.
tx-copybreak N
Set the tx copybreak value in bytes.
tx-buf-size N
Set the tx copybreak buffer size in bytes.
pfc-prevention-tout N
Set pfc prevention timeout in msecs. Value of 0 means disable and 65535 means auto.
--reset
Reset hardware components specified by flags and components listed below
flags N
Resets the components based on direct flags mask
mgmt Management processor
irq Interrupt requester
dma DMA engine
filter Filtering/flow direction
offload
Protocol offload
mac Media access controller
phy Transceiver/PHY
ram RAM shared between multiple components ap Application Processor
dedicated
All components dedicated to this interface
all All components used by this interface, even if shared
--show-fec
Queries the specified network device for its support of Forward Error Correction.
--set-fec
Configures Forward Error Correction for the specified network device.
Forward Error Correction modes selected by a user are expected to be persisted after any hotplug events. If a module is swapped that does not support the cur‐
rent FEC mode, the driver or firmware must take the link down administratively and report the problem in the system logs for users to correct.
encoding auto|off|rs|baser|llrs [...]
Sets the FEC encoding for the device. Combinations of options are specified as e.g. encoding auto rs ; the semantics of such combinations vary between
drivers.
auto Use the driver's default encoding
off Turn off FEC
RS Force RS-FEC encoding
BaseR Force BaseR encoding
LLRS Force LLRS-FEC encoding
-Q|--per-queue
Applies provided sub command to specific queues.
queue_mask %x
Sets the specific queues which the sub command is applied to. If queue_mask is not set, the sub command will be applied to all queues.
sub_command
Sub command to apply. The supported sub commands include --show-coalesce and --coalesce.
q.B --cable-test
Perform a cable test and report the results. What results are returned depends on the capabilities of the network interface. Typically open pairs and shorted
pairs can be reported, along with pairs being O.K. When a fault is detected the approximate distance to the fault may be reported.
--cable-test-tdr
Perform a cable test and report the raw Time Domain Reflectometer data. A pulse is sent down a cable pair and the amplitude of the reflection, for a given dis‐
tance, is reported. A break in the cable returns a big reflection. Minor damage to the cable returns a small reflection. If the cable is shorted, the amplitude
of the reflection can be negative. By default, data is returned for lengths between 0 and 150m at 1m steps, for all pairs. However parameters can be passed to
restrict the collection of data. It should be noted, that the interface will round the distances to whatever granularity is actually implemented. This is often
0.8 of a meter. The results should include the actual rounded first and last distance and step size.
first N
Distance along the cable, in meters, where the first measurement should be made.
last N
Distance along the cable, in meters, where the last measurement should be made.
step N
Distance, in meters, between each measurement.
pair N
Which pair should be measured. Typically a cable has 4 pairs. 0 = Pair A, 1 = Pair B, ...
--monitor
Listens to netlink notification and displays them.
command
If argument matching a command is used, ethtool only shows notifications of this type. Without such argument or with --all, all notification types are
shown.
devname
If a device name is used as argument, only notification for this device are shown. Default is to show notifications for all devices.
--show-tunnels
Show tunnel-related device capabilities and state. List UDP ports kernel has programmed the device to parse as VxLAN, or GENEVE tunnels.
--show-module
Show the transceiver module's parameters.
--set-module
Set the transceiver module's parameters.
power-mode-policy high|auto
Set the power mode policy for the module. When set to high, the module always operates at high power mode. When set to auto, the module is transitioned by
the host to high power mode when the first port using it is put administratively up and to low power mode when the last port using it is put administrative‐
ly down. The power mode policy can be set before a module is plugged-in.
BUGS
Not supported (in part or whole) on all network drivers.
TMP
Ein divenhaft zickendes LAN vergällt Admins nicht nur den Arbeitstag. Nein, auch zu Hause sorgen falsch ausgehandelte Ethernets für Verdruss. Doch wie in Hollywood naht Rettung in letzter Sekunde. Murphy nahm vor ein paar Tagen denselben Bus wie ich und ließ sich, anfangs unbemerkt, in meiner Wohnung nieder. Als ich mein Notebook hochfuhr, schlug er hinterrücks zu. Mein harmloser Plan: Ich wollte mir nur im Arbeitszimmer das gerade laufende Fernsehprogramm per Streaming anschauen.
Im Wohnzimmer steht dazu ein VDR [1], die Verbindung zwischen beiden schafft mein sehr gepflegtes heimischen Netz [2]. Doch die Enttäuschung war groß, als jeder Film mit Breakdancern besetzt zu sein schien, so ruckelte das Ganze.
Hardware prima, Video unbrauchbar
Die (etwas längliche) Diagnose der Netzwerkhardware brachte nichts. Auf meinem Switch gab es nichts zu diagnostizieren, da er ein dummes Gerät ohne Managementfunktionen ist. Am Ende verhalf mir Ethtool [3] zur filmreifen Erkenntnis: Das automatische Aushandeln der Übertragungsparameter zwischen Switch und Gigabit-Port des Notebooks, die Auto-Negotiation, hat versagt. Nicht nur, dass lediglich 100 MBit/s statt des Zehnfachen anlagen, es war auch verständlicherweise auf Halbduplex eingestellt (siehe Abbildung 1). Kein Wunder, dass der Datenfluss schneckig wirkte.
Abbildung 1: Ethtool findet heraus, dass trotz erfüllter Voraussetzungen keine Gigabit-LAN-Verbindung mit Vollduplex zustande kommt.
Fehler bei der Auto-Negotiation sind eine klassische Domäne für Murphy. Sie passieren oft genug, um zu nerven, aber nicht so häufig, dass man bei der Diagnose gerade daran zuerst denkt. Manchmal lässt sich das Malheur schon durch erneutes Auslösen der Autoneg beheben (sprich: Kabel raus, Kabel rein), manchmal nicht. Netzwerker berichten von Situationen, in denen sie zehn Netzwerkkarten desselben Herstellers, sogar aus einer Charge, an denselben Switch hängten – bei sieben funktioniert die Autoneg, bei dreien nicht.
Perfide ist, dass erst einmal alles zu klappen scheint. Das Link-Lämpchen leuchtet, auf Pings kommen prompte Antworten. Alles klar. Bis der Erste versucht größere Datenmengen über das Interface zu schieben. Mit etwas Glück fällt gleich bei »ifconfig« der muntere Kollisionszähler auf. Kollisionen sollte es in einem geswitchten Netz überhaupt nicht geben. Andernfalls ist mit höchster Wahrscheinlichkeit eine Halbduplex-Verbindung im Spiel.
Reparaturbetrieb
Glücklicherweise kann Ethtool derartige Missstände nicht nur diagnostizieren, sondern auch beheben. Denn das Kommando »ethtool -r eth0« startet die Auto-Negotiation erneut. Das ist eleganter, als das Netzwerkkabel zu ziehen, und ohnehin die einzige Möglichkeit, wenn kein physikalischer Zugriff auf die Hardware möglich ist. Mein Vertrauen in die Autoneg hat sich jedoch inzwischen vollständig verflüchtigt. Darum stelle ich mit
ethtool -s eth0 speed 1000 duplex full autoneg off
lieber die Werte hart ein. Wer (im Gegensatz zu mir) einen Managed Switch hat, tut gut daran, die Werte auch dort fest zu verdrahten.
Ethtool ist noch für einige Spielereien zu haben. So vermag es die WOL-Einstellungen (Wake on LAN) präzise zu steuern; die Programmdokumentation weiß Näheres. Bedeutsamer ist eine Funktion, die auf den ersten Blick wie ein ebenso nettes wie nutzloses Gimmick aussieht. Das Kommando »ethtool -p eth0« bringt die Netzwerkkarte dazu, rhythmisch mit ihren LEDs zu blinken. Wer schon einmal vor einem Server mit acht NICs stand und herauszufinden versuchte, welche davon »eth0« ist, lernt dieses Feature schätzen. Einen ungestörten Fernsehabend kann eine blinkende LED freilich nicht ersetzen. (jk)
| Infos |
| [1] VDR: [http://www.cadsoft.de/vdr/]
[2] Wenn es diese Kolumne als Podcast gäbe, könnte der geneigte Leser an dieser Stelle das Prusten und Glucksen meiner holden Gattin vernehmen. [3] Ethtool: [http://freshmeat.net/redir/ethtool/20128/url_homepage/gkernel] |