1IMP(4) Kernel Interfaces Manual IMP(4)
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6 imp - 1822 network interface
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9 /sys/conf/SYSTEM:
10 NIMP count # ARPAnet IMP 1822 interface
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13 The imp interface, as described in BBN Report 1822, provides access to
14 an intelligent message processor normally used when participating in
15 the Department of Defense ARPA network. The network interface communi‐
16 cates through a device controller, usually an ACC LH/DH or HDH or a DEC
17 IMP-11A, with the IMP. The interface is “reliable” and “flow-con‐
18 trolled” by the host-IMP protocol.
19 To configure IMP support, at least one of acc(4), css(4) or hdh(4) must
21 be included. The count specifies the total number of IMP connections.
22 The network number on which the interface resides is specified at boot
23 time using the SIOCSIFADDR ioctl. The host number is discovered
24 through receipt of NOOP messages from the IMP.
25 The network interface is always in one of four states: up, down, ini‐
27 tializing, or going down. When the system is booted, the interface is
28 marked down. If the hardware controller is successfully probed, the
29 interface enters the initializing state and transmits three NOOP mes‐
30 sages to the IMP. It then waits for the IMP to respond with two or
31 more NOOP messages in reply. When it receives these messages it enters
32 the up state. The ``going down'' state is entered only when notified
33 by the IMP of an impending shutdown. Packets may be sent through the
34 interface only while it is in the up state. Outgoing packets are
35 dropped with the error ENETDOWN returned to the caller if the interface
36 is in any other state.
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39 imp%d: not configured. A hardware interface could not be attached dur‐
40 ing autoconfiguration because too few IMP pseudo-devices were config‐
41 ured.
42 imp%d: leader error. The IMP reported an error in a leader (1822 mes‐
44 sage header). This causes the interface to be reset and any packets
45 queued up for transmission to be purged.
46 imp%d: going down in 30 seconds.
48 imp%d: going down for hardware PM.
49 imp%d: going down for reload software.
50 imp%d: going down for emergency reset. The Network Control Center
51 (NCC) is manipulating the IMP. By convention these messages are
52 reported to all hosts on an IMP.
53 imp?: host %x, lost %d rfnms. The IMP had messages outstanding to the
55 host listed, but no RFNM (Request for Next Message) messages were
56 received from the IMP in 127 seconds. The software state for that host
57 is reinitialized.
58 imp%d: interface reset. The host has received an interface reset mes‐
60 sage from the IMP.
61 imp%d: address reset to x%x (%d/%d). The host has received a NOOP mes‐
63 sage which caused it to reset its notion of its current address. The
64 Internet address is printed in hexadecimal, with the host and IMP num‐
65 bers following. This indicates that the address originally set by
66 ifconfig(8) was incorrect, that the IMP has undergone an identity cri‐
67 sis, or that communication between the IMP and the host is being gar‐
68 bled.
69 imp%d: data error. The IMP noted an error in data transmitted. The
71 host-IMP interface is reset and the host enters the init state (await‐
72 ing NOOP messages).
73 imp%d: interface reset. The reset process has been completed.
75 imp%d: marked down. After receiving a “going down in 30 seconds” mes‐
77 sage, and waiting 30 seconds, the host has marked the IMP unavailable.
78 Before packets may be sent to the IMP again, the IMP must notify the
79 host, through a series of NOOP messages, that it is back up.
80 imp%d: can't handle af%d. The interface was handed a message with
82 addresses formatting in an unsuitable address family; the packet was
83 dropped.
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86 intro(4N), inet(4F), acc(4), css(4), hdh(4), implog(8), implogd(8)
873rd Berkeley Distribution August 2, 1987 IMP(4)