in response to a type 0 message from a host that
contained an erroneous Source Host or Destination Host
field. Its sub-types are:
0: The Source Host 1822L name is not authorized or not
effective.
1: The Source Host 1822L address does not match the
host port used to send the message.
2: The Destination Host 1822L name is not authorized.
3: The Destination Host 1822L name is authorized but
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RFC802 Andrew G. Malis
not effective, even though the named host is up.
If the host were actually down, a type 7 message
would be returned, not a type 15.
4: The Source or Destination Host field contains a
1822L name, but the host being addressed is on a
non-C/30 IMP (see Figure 4 in section 2.2).
5-15: Unassigned.
Types 11-14,16-255: Unassigned.
Bits 33-48: Source Host:
For type 0 messages, this field contains the 1822L name or
address of the host that originated the message. All
replies to the message should be sent to the host specified
herein. For message types 5-9, 11 and 15, this field
contains the source host field used in a previous type 0
message sent by this host.
Bits 49-64: Destination Host:
For type 0 messages, this field contains the 1822L name or
address that the message was sent to. This allows the
destination host to detect how it was specified by the
source host. For message types 5-9, 11 and 15, this field
contains the destination host field used in a previous type
0 message sent by this host.
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RFC802 Andrew G. Malis
Bits 65-76: Message ID:
For message types 0, 5, 7-9, 11 and 15, this is the value
assigned by the source host to identify the message (see
section 3.1). This field is also used by message types 2
and 6.
Bits 77-80: Sub-type:
This field is used as a modifier by message types 0-2, 4-7,
9, 11 and 15.
Bits 81-96: Message Length:
This field is contained in type 0 and type 3 messages only,
and is the actual length in bits of the message (exclusive
of leader, leader padding, and hardware padding) as computed
by the IMP.
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RFC802 Andrew G. Malis
4 REFERENCES
[1] Specifications for the Interconnection of a Host and an IMP,
BBN Report 1822, May 1978 Revision.
[2] E. C. Rosen et. al., ARPANET Routing Algorithm Improvements,
IEN 183 (also published as BBN Report 4473, Vol. 1), August
1980, pp. 55-107.
[3] J. Postel, Assigned Numbers, RFC790, September 1981, p. 10.
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RFC802 Andrew G. Malis
INDEX
1822...................................................... 4
1822 address.............................................. 6
1822 host................................................. 5
1822L..................................................... 4
1822L address............................................. 7
1822L host................................................ 5
1822L name................................................ 6
authorized................................................ 9
blocking................................................. 16
congestion control................................... 22, 39
connection........................................... 20, 38
destination host..................................... 32, 40
effective................................................ 10
flow control......................................... 20, 38
handing type......................................... 27, 35
incomplete transmission message...................... 19, 37
leader flags......................................... 27, 35
link field............................................... 32
logical addressing........................................ 4
message ID........................................... 32, 41
message length........................................... 41
message type......................................... 28, 35
multi-homing.............................................. 4
NDM.................................................. 10, 28
NDM reply............................................ 10, 36
NOC....................................................... 9
NOP........................................... 5, 22, 30, 36
outstanding.............................................. 21
priority bit............................................. 27
regular message...................................... 28, 35
RFNM..................................................... 36
short-blocking feature................................... 15
short-blocking message............................... 19, 28
source host.......................................... 31, 40
standard message......................................... 28
sub-type............................................. 32, 41
symmetric................................................. 5
trace bit............................................ 27, 35
uncontrolled message................................. 14, 28