4.3BSD-UWisc/man/cat4/imp.4
IMP(4) UNIX Programmer's Manual IMP(4)
NAME
imp - 1822 network interface
SYNOPSIS
pseudo-device imp [ count ]
DESCRIPTION
The _i_m_p interface, as described in BBN Report 1822, provides
access to an intelligent message processor normally used
when participating in the Department of Defense ARPA net-
work. The network interface communicates 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-
controlled" by the host-IMP protocol.
To configure IMP support, at least one of _a_c_c(4), _c_s_s(4) or
_h_d_h(4) must be included. The optional _c_o_u_n_t specifies the
total number of IMP connections. The network number on
which the interface resides is specified at boot time using
the SIOCSIFADDR ioctl. The host number is discovered
through receipt of NOOP messages from the IMP.
The network interface is always in one of four states: up,
down, initializing, or going down. When the system is
booted, the interface is marked down. If the hardware con-
troller is successfully probed, the interface enters the
initializing state and transmits three NOOP messages 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 during autoconfiguration because too few IMP
pseudo-devices were configured.
imp%d: leader error. The IMP reported an error in a leader
(1822 message 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.
Printed 12/27/86 May 16, 1986 1
IMP(4) UNIX Programmer's Manual IMP(4)
imp?: host %x, lost %d rfnms. The IMP had messages out-
standing 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 message from the IMP.
imp%d: address reset to x%x (%d/%d). The host has received
a NOOP message which caused it to reset its notion of its
current address. The Internet address is printed in hexade-
cimal, with the host and IMP numbers following. This indi-
cates that the address originally set by _i_f_c_o_n_f_i_g(8) was
incorrect, that the IMP has undergone an identity crisis, or
that communication between the IMP and the host is being
garbled.
imp%d: data error. The IMP noted an error in data transmit-
ted. The host-IMP interface is reset and the host enters
the init state (awaiting NOOP messages).
imp%d: interface reset. The reset process has been com-
pleted.
imp%d: marked down. After receiving a "going down in 30
seconds" message, 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 mes-
sage with addresses formatting in an unsuitable address fam-
ily; the packet was dropped.
SEE ALSO
intro(4N), inet(4F), acc(4), css(4), hdh(4), implog(8),
implogd(8)
Printed 12/27/86 May 16, 1986 2