man(1) Manual page archive


     ETHER(3)                                                 ETHER(3)

     NAME
          ether - Ethernet device

     SYNOPSIS
          bind -a #ln /net

          /net/ethern/clone
          /net/ethern/addr
          /net/ethern/mtu
          /net/ethern/ifstats
          /net/ethern/stats
          /net/ethern/[0-7]
          /net/ethern/[0-7]/data
          /net/ethern/[0-7]/ctl
          /net/ethern/[0-7]/ifstats
          /net/ethern/[0-7]/stats
          /net/ethern/[0-7]/type

     DESCRIPTION
          The Ethernet interface, /net/ethern, is a directory contain-
          ing subdirectories, one for each distinct Ethernet packet
          type, and clone, addr, mtu, ifstats, and stats files.  stats
          and ifstats are the same as in the subdirectories (see
          below).  Reading addr returns the MAC address of this inter-
          face in hex with no punctuation and no trailing newline.
          Reading mtu returns 3 12-byte numbers: the hardware's mini-
          mum MTU, the current MTU and the maximum MTU supported by
          the interface.  The MTU is set by writing mtu n into the ctl
          file.  The number n (optional in the bind) is the device
          number of the card, permitting multiple cards to be used on
          a single machine.

          Each directory contains files to control the associated con-
          nection, receive and send data, and supply statistics.
          Incoming Ethernet packets are demultiplexed by packet type
          and passed up the corresponding open connection.  Reading
          from the data file reads packets of that type arriving from
          the network.  A read will terminate at packet boundaries.
          Each write to the data file causes a packet to be sent.  The
          Ethernet address of the interface is inserted into the
          packet header as the source address unless l2bridge is set.

          A connection is assigned to a packet type by opening its ctl
          file and writing connect n where n is a decimal integer con-
          stant identifying the Ethernet packet type.  A type of -1
          enables the connection to receive copies of packets of all
          types.  A type of -2 enables the connection to receive
          copies of the first 64 bytes of packets of all types.  If
          multiple connections are assigned to a given packet type a
          copy of each packet is passed up each connection.

     ETHER(3)                                                 ETHER(3)

          Some interfaces also accept unique options when written to
          the ctl (or clone) file; see the description of wavelan in
          plan9.ini(8). The control messages described in ip(3) under
          Configuring interfaces from `bridge' to `headersonly' are
          understood.  The additional control message `nonblocking'
          makes write systems calls to this interface non-blocking iff
          followed by nothing or a non-zero integer; a following `0'
          makes writes block on a full output queue.

          Reading the ctl file returns the decimal index of the asso-
          ciated connection, 0 through 7.  Reading the type file
          returns the decimal value of the assigned Ethernet packet
          type.  Reading the stats file returns status information
          such as the Ethernet address of the card and general statis-
          tics, independent of the interface; ifstats contains
          device-specific data and statistics about the card.  The
          format of the stats file is stat:value....  In particular,
          if link is non-zero, mbps is the current speed of the inter-
          face in megabits-per-second.  While in and out are the total
          number of packets input or output and do differ (in the case
          of dropped packets or loop back) from hardware counters.

          An interface normally receives only those packets whose des-
          tination address is that of the interface, the broadcast
          address, ff:ff:ff:ff:ff:ff, or a a multicast address
          assigned to the interface.  Multicast addresses are added by
          writing addmulti ea and remove by writing remmulti ea to the
          ctl file.  Multicast addresses are automatically dropped
          when the connection is closed.  The interface can be made to
          receive all packets on the network by writing the string
          promiscuous to the ctl file. The interface remains promiscu-
          ous until the control file is closed by all connections
          requesting promiscuous mode.  The extra packets are passed
          up connections of types -1 and -2 only.

          Writing bridge to the ctl file causes loop back packets to
          be ignored.  This is useful for layer 3 bridging.  Writing
          l2bridge also allows the connection to set the source
          address and receive packets with any destination address.
          Writing scanbs [ secs ] starts a scan for wireless base sta-
          tions and sets the scanning interval to secs. Scanning is
          terminated when the connection is closed.  The default
          interval is 5s. For wired connections, this command is
          ignored.

     SOURCE
          /sys/src/9/*/devether.c
          /sys/src/9/port/netif.c

     SEE ALSO
          ip(3).

     ETHER(3)                                                 ETHER(3)

     BUGS
          The multicast interface makes removal of multicast addresses
          on that rely on hashing difficult.

          Interface MTU settings must be greater than those used by
          ip(3); this is not enforced.  NB: interface MTU is different
          than IP stack's MTU.