4.3BSD - /usr/man/cat4/imp.0

IMP(4)                                                                  IMP(4)


NAME
       imp - 1822 network interface

SYNOPSIS
       pseudo-device imp [ count ]

DESCRIPTION
       The  imp interface, as described in BBN Report 1822, provides access to
       an intelligent message processor normally used  when  participating  in
       the Department of Defense ARPA network.  The network interface communi‐
       cates through a device controller, usually an ACC LH/DH or HDH or a DEC
       IMP-11A,  with  the  IMP.   The  interface is “reliable” and “flow-con‐
       trolled” by the host-IMP protocol.

       To configure IMP support, at least one of acc(4), css(4) or hdh(4) must
       be included.  The optional count specifies the total number of IMP con‐
       nections.  The network number on which the interface resides is  speci‐
       fied at boot time using the SIOCSIFADDR ioctl.  The host number is dis‐
       covered through receipt of NOOP messages from the IMP.

       The network interface is always in one of four states: up,  down,  ini‐
       tializing,  or going down.  When the system is booted, the interface is
       marked down.  If the hardware controller is  successfully  probed,  the
       interface  enters  the initializing state and transmits three NOOP mes‐
       sages to the IMP.  It then waits for the IMP to  respond  with  two  or
       more NOOP messages in reply.  When it receives these messages it enters
       the up state.  The ‘‘going down’’ state is entered only  when  notified
       by  the  IMP of an impending shutdown.  Packets may be sent through the
       interface only while it is in  the  up  state.   Outgoing  packets  are
       dropped with the error ENETDOWN returned to the caller if the interface
       is in any other state.

DIAGNOSTICS
       imp%d: not configured.  A hardware interface could not be attached dur‐
       ing  autoconfiguration  because too few IMP pseudo-devices were config‐
       ured.

       imp%d: leader error.  The IMP reported an error in a leader (1822  mes‐
       sage  header).   This  causes the interface to be reset and any packets
       queued up for transmission to be purged.

       imp%d: going down in 30 seconds.
       imp%d: going down for hardware PM.
       imp%d: going down for reload software.
       imp%d: going down for emergency  reset.   The  Network  Control  Center
       (NCC)  is  manipulating  the  IMP.   By  convention  these messages are
       reported to all hosts on an IMP.

       imp?: host %x, lost %d rfnms.  The IMP had messages outstanding to  the
       host  listed,  but  no  RFNM  (Request  for Next Message) messages were
       received from the IMP in 127 seconds.  The software state for that host
       is reinitialized.

       imp%d:  interface reset.  The host has received an interface reset mes‐
       sage from the IMP.

       imp%d: address reset to x%x (%d/%d).  The host has received a NOOP mes‐
       sage  which  caused it to reset its notion of its current address.  The
       Internet address is printed in hexadecimal, with the host and IMP  num‐
       bers  following.   This  indicates  that  the address originally set by
       ifconfig(8) was incorrect, that the IMP has undergone an identity  cri‐
       sis,  or  that  communication  between  the  IMP  and the host is being
       garbled.

       imp%d: data error.  The IMP noted an error in  data  transmitted.   The
       host-IMP  interface is reset and the host enters the init state (await‐
       ing NOOP messages).

       imp%d: interface reset.  The reset process has been completed.

       imp%d: marked down.  After receiving a “going down in 30 seconds”  mes‐
       sage,  and waiting 30 seconds, the host has marked the IMP unavailable.
       Before packets may be sent to the IMP again, the IMP  must  notify  the
       host, through a series of NOOP messages, that it is back up.

       imp%d:  can’’t  handle  af%d.   The  interface was handed a message with
       addresses formatting in an unsuitable address family;  the  packet  was
       dropped.

SEE ALSO
       intro(4N), inet(4F), acc(4), css(4), hdh(4), implog(8), implogd(8)


4.2 Berkeley Distribution        May 16, 1986                           IMP(4)