ethtool(8) - phpMan

ETHTOOL(8)                  System Manager's Manual                 ETHTOOL(8)

NAME
       ethtool - query or control network driver and hardware settings
SYNOPSIS
       ethtool devname
       ethtool -h|--help
       ethtool --version
       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]
       ethtool -g|--show-ring devname
       ethtool -G|--set-ring devname [rx N] [rx-mini N] [rx-jumbo N] [tx 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
       ethtool --phy-statistics devname
       ethtool -t|--test devname [offline|online|external_lb]
       ethtool -s devname [speed N] [duplex half|full] [port tp|aui|bnc|mii]
              [mdix auto|on|off] [autoneg on|off] [advertise N] [phyad N]
              [xcvr internal|external] [wol p|u|m|b|a|g|s|d...]
              [sopass xx:yy:zz:aa:bb:cc] [msglvl N | 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:...]
              [ 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]
       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 --show-fec devname
       ethtool --set-fec devname [encoding auto|off|rs|baser]

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 oper-
       ate.

OPTIONS
       ethtool with a single argument specifying the device name  prints  cur-
       rent settings of the specified device.
       -h --help
              Shows a short help message.
       --version
              Shows the ethtool version number.
       -a --show-pause
              Queries the specified Ethernet device for pause parameter infor-
              mation.
       -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 de-
              vice.
           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.
       -i --driver
              Queries the specified network device for associated  driver  in-
              formation.
       -d --register-dump
              Retrieves  and  prints a register dump for the specified network
              device.  The register format for some devices is known  and  de-
              coded others are printed in hex.  When raw is enabled, then eth-
              tool dumps the raw register data to stdout.  If file  is  speci-
              fied,  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  cer-
              tain portions of the EEPROM.  Default is to dump the entire EEP-
              ROM.
           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  na-
              ture  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 speci-
              fied 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 en-
                  abled.
           ufo on|off
                  Specifies whether UDP fragmentation offload  should  be  en-
                  abled
           gso on|off
                  Specifies whether generic segmentation offload should be en-
                  abled
           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  in-
              volves 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 ad-
              dress.
       -r --negotiate
              Restarts auto-negotiation on the specified Ethernet  device,  if
              auto-negotiation is enabled.
       -S --statistics
              Queries the specified network device for NIC- and driver-specif-
              ic statistics.
       --phy-statistics
              Queries the specified network device for  PHY  specific  statis-
              tics.
       -t --test
              Executes  adapter selftest on the specified network device. Pos-
              sible test modes are:
           offline
                  Perform full set of tests, possibly interrupting normal  op-
                  eration during the tests,
           online Perform limited set of tests, not interrupting normal opera-
                  tion,
           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.
           duplex half|full
                  Sets full or half duplex mode.
           port tp|aui|bnc|mii
                  Selects device port.
           mdix auto|on|off
                  Selects MDI-X mode for port. May be used to override the au-
                  tomatic 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 immediately, and if necessary may reset the  link  to
                  cause the change to take effect.
           autoneg on|off
                  Specifies whether autonegotiation should be enabled. Autone-
                  gotiation 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 combina-
                  tion of the following values:
                  0x001                 10baseT Half
                  0x002                 10baseT Full
                  0x004                 100baseT Half
                  0x008                 100baseT Full
                  0x010                 1000baseT Half               (not supported by IEEE standards)
                  0x020                 1000baseT Full
                  0x20000               1000baseKX Full
                  0x20000000000         1000baseX Full
                  0x800000000000        2500baseT Full
                  0x8000                2500baseX Full               (not supported by IEEE standards)
                  0x1000000000000       5000baseT Full
                  0x1000                10000baseT Full
                  0x40000               10000baseKX4 Full
                  0x80000               10000baseKR Full
                  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
                  0x4000000000000000    200000baseKR4 Full
                  0x8000000000000000    200000baseSR4 Full
                  0x10000000000000000   200000baseLR4_ER4_FR4 Full
                  0x20000000000000000   200000baseDR4 Full
                  0x40000000000000000   200000baseCR4 Full
           phyad N
                  PHY address.
           xcvr internal|external
                  Selects transceiver type. Currently only internal and exter-
                  nal  can  be specified, in the future further types might be
                  added.
           wol p|u|m|b|a|g|s|d...
                  Sets Wake-on-LAN options.  Not  all  devices  support  this.
                  The argument to this option is a string of characters speci-
                  fying 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 MagicPackettm
                  s   Enable SecureOntm password for MagicPackettm
                  d   Disable  (wake  on  nothing).   This  option
                      clears all previous options.
           sopass xx:yy:zz:aa:bb:cc
                  Sets  the  SecureOntm 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 defined type names and num-
                  bers 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|sctp6
           m|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 ap-
           pended, 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 op-
                  tional 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 incom-
                  ing 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 (ap-
                  plicable  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 in-
                  coming 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 ac-
                  tion.
                  -1            Drop the matched flow
                  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 re-
                  turned by ethtool -X ... context new.
           loc N  Specify the location/ID to insert the rule. This will  over-
                  write  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 de-
              vice.   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 output.
           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  con-
                  junction 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 written.  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  mod-
              ules,  e.g SFP+, QSFP.  If the driver and module support it, the
              optical diagnostic information is also read and decoded.
       --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 specifica-
              tions)
       --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.
       --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  current  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
                  Sets the FEC encoding for the device.
                  auto    Use the driver's default encoding
                  off     Turn off FEC
                  RS      Force RS-FEC encoding
                  BaseR   Force BaseR encoding
BUGS
       Not supported (in part or whole) on all network drivers.
AUTHOR
       ethtool was written by David Miller.
       Modifications by Jeff Garzik, Tim Hockin, Jakub Jelinek, Andre Majorel,
       Eli Kupermann, Scott Feldman,  Andi  Kleen,  Alexander  Duyck,  Sucheta
       Chakraborty, Jesse Brandeburg, Ben Hutchings.
AVAILABILITY
       ethtool                 is                available                from
       <http://www.kernel.org/pub/software/network/ethtool/>;

Ethtool version 4.8              October 2016                       ETHTOOL(8)