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rfc:ien:ien197
                          IEN - 197
                 A Host Monitoring Protocol
                    Benjamin M. Littauer
                       Andrew J. Huang
                      Robert M. Hinden
                Bolt Beranek and Newman Inc.
                       September 1981

IEN-197 September 1981

                      Table of Contents

1 Introduction…………………………………… 1 2 Protocol Operation……………………………… 2 2.1 Unsolicited Messages………………………….. 3 2.2 Status Messages………………………………. 4 2.3 Statistics Messages…………………………… 4 3 Header Formats…………………………………. 6 3.1 IP Headers…………………………………… 6 3.2 Monitor Header……………………………….. 7 4 Monitor Message Formats…………………………. 9 4.1 System Type 1: General Messages………………… 9 4.1.1 Message Type 1: Polling Message………………. 9 4.1.2 Message Type 2: Error in Poll……………….. 11 4.2 System Type 2: IMP…………………………… 13 4.2.1 Message Type 1: IMP Trap……………………. 13 4.2.2 Message Type 2: IMP status………………….. 16 4.2.3 Message Type 3: IMP Modem Throughput…………. 20 4.2.4 Message Type 4: IMP Host Throughput………….. 23 4.3 System Type 3: TAC…………………………… 26 4.3.1 Message Type 1: TAC Trap Message…………….. 26 4.3.2 Message Type 2: TAC Status………………….. 29 4.3.3 Message Type 3: TAC Throughput………………. 32

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IEN-197 September 1981

                 A Host Monitoring Protocol

1 Introduction

   The Host Monitoring   Protocol  (HMP)  is  used  to  collect

information from hosts in various networks. At present the

protocol aims at collecting information from ARPANET IMPs and

TACs in an internet environment. It is designed to be

extensible to other monitoring functions (e.g. hosts, gateways,

local nets) while its addressing and control structures allow

it to operate as well within a single network. In

implementation it is a portion of a larger system, the Network

Operations Center (NOC).

   The   monitoring   algorithm   relies   on    polling    for

messages; the Host Monitor (HM) periodically sends a polling

message to the host being monitored, requesting a specified

report. The host then creates the report and sends it to the HM.

Missing reports are detected as unanswered polls and duplicate

polls are sent to have the report retransmitted. Some messages

cannot be polled for and these are sent to the HM

spontaneously. Checksums calculated on the data portions of all

messages assure their integrity.

   The  HMP implements a password scheme in order  to  restrict

access to monitoring information. The monitored hosts check each

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IEN-197 September 1981

poll message for a valid password before responding; this helps

prevent unauthorized use of the monitor system. The HMP is not

intended to be a highly secure protocol.

2 Protocol Operation

   The   HMP  is  designed   to   operate   reliably   in   the

internet environment. To gain this measure of

reliability it uses polling. The HM sends polling messages

requesting reports to the monitored hosts. A host, upon

receiving the poll, verifies the message and, if it is

acceptable, sends the appropriate report to the poll source. The

HM, after transmitting the poll, awaits the corresponding report.

If it is not received within a reasonable interval, another

poll is sent assuming that either the previous poll or the

answering report was lost. If after a number of repeated

polls no response has been received, it can be reasonably

concluded that the host is unreachable and the polling frequency

is reduced to a background level. This minimizes traffic

but, since polling continues, a poll will reach the host once it

becomes reachable. When a report is received the normal poll

frequency is resumed.

   The most important reason for choosing  polling  over  other

methods of detecting lost messages is that it centralizes control

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IEN-197 September 1981

of monitoring in a dedicated HM, rather distributing it

throughout the network of monitored hosts. This frees resources

in the monitored systems and also allows the HM to regulate the

flow of monitoring messages to prevent overloading of the HM's

resources.

   There are three classes of data with  which  the  monitoring

protocol is concerned. These are (1) reports of unexpected

changes of status or error conditions, (2) reports of the current

state of the host, and (3) reports of statistics and throughput

data. These three kinds of data are handled in different ways by

the HMP as described below.

2.1 Unsolicited Messages

   These are reports of unexpected changes of status  or  error

condition reports (traps) which the monitor should be informed of

as they occur. They are not polled, but are instead sent

directly to a particular HM. If the address of the HM must be

changed for unsolicited messages, it will be done by external

means (e.g. packet core protocol).

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IEN-197 September 1981

2.2 Status Messages

   These are reports of the current state  of  a  system;  they

contain any kind of information which is not cumulative. The HM

will poll for these on a periodic basis. When a monitored host

receives a poll for a status message, it assembles a message with

the current data pertaining to its status. Since this is an

instantaneous "picture" of a system, it is not critical if any

particular status report is lost.

2.3 Statistics Messages

   These messages, also  called  throughput  messages,  contain

data collected on a periodic basis. The information will be

collected in a monitored machine using a double buffering system.

At the end of each collection period, a message will be assembled

and the counters will be cleared. During the next collection

period, any HMs polling for a statistics message will be sent

this message.

   The collection frequency  for  statistics  messages  from  a

particular host must be relatively long compared to the average

round trip message time between the HM and that host to allow the

HM to re-poll if it does not receive an answer. With this

restriction it should be possible to avoid missing any statistics

messages in most cases. Each statistics message will contain a

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IEN-197 September 1981

field giving the (local) time when the data was collected, and

the time at which the message was sent (*). This will allow the

HM to schedule its polling so that the poll arrives near the

beginning of each collection period. This is done to ensure that

if a message is lost, the HM will have sufficient time to try

again to get the statistics message for that period. Sequence

numbers will be used to detect the loss of a message for a

period, and also to eliminate duplicate messages.

___ * The units of the local time should be large enough to guarantee a rollover time of at least one hour.

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IEN-197 September 1981

3 Header Formats

   [Note:   Any  field  labeled "unused" is reserved for  later
   extensions and must be zero when sent.]
   Monitor messages have the following format:
                  +----------------+
                  |  Local Network |
                  |    Header(s)   |
                  +----------------+
                  |  IP header     |
                  +----------------+
                  |  Internet      |
                  |    Monitor     |
                  |      Header    |
                  +----------------+
                  |    D           |
                  |      A         |
                  |        T       |
                  |          A     |
                  +----------------+
                  |  Padding       |
                  +----------------+
   The local header(s) depend on the local network, and do  not
   concern us here.

3.1 IP Headers

   HMP messages are sent using  the  version  4  IP  header  as
   described  in IEN-128 (RFC-760).  The HMP protocol number is
   20 (decimal).  The time to live field should be set  to  the
   maximum  value.  All other fields should be set as specified
   in IEN-128.
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IEN-197 September 1981

3.2 Monitor Header

   The monitor header format is:
                1             0 0             0
                5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
               +---------------+---------------+
             0 |  System Type  | Message Type  |
               +---------------+---------------+
             1 |          Port Number          |
               +---------------+---------------+
             2 |        Sequence Number        |
               +---------------+---------------+
             3 |  Password or Returned Seq. #  |
               +---------------+---------------+
             4 |   One's Complement Checksum   |
               +---------------+---------------+

HMP FIELDS:

System Type Message Type

   The combination  of system type and message type  determines
   the format of the data in the monitoring message.
   The system types which have been defined are:
                 System Type  | Meaning
              ----------------+-----------------
                     1        | General Messages
                     2        | IMP
                     3        | TAC
   Message types are defined for each system type according  to
   the  needs  of that system.  Message types and their formats
   for each system are defined below.

Port Number

   The Port Number field is presently unused.  It can  be  used
   to multiplex similar messages from/to different processes in
   one host.

Sequence Number

   Every message contains  a  sequence  number.   The  sequence
   number  is incremented when each new message of that type is
   sent.
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IEN-197 September 1981

Password or Returned Sequence Number

   The  Password field of a polling message from an HM contains
   a  password  to   verify  that the  HM  is allowed to gather
   information.  Responses  to  polling   messages   copy   the
   Sequence Number from  the  polling message  and return it in
   this  field   for   identification   and   round-trip   time
   calculations.

Checksum

   The  Checksum  field  is  the one's complement of the  one's
   complement  sum of all the 16-bit words in  the  header  and
   data  area.   As  with  the checksum in the TCP header  (see
   IEN-129),  the  checksum  also covers a 96-bit pseudo header
   containing  the source address, the destination address, the
   protocol  (20),  and the length of the monitoring message in
   bytes. The  fields  of the pseudo header are as defined  for
   the IP header.
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IEN-197 September 1981

4 Monitor Message Formats

4.1 System Type 1: General Messages

4.1.1 Message Type 1: Polling Message

Description

   The  HM will send polls to the  machines  it  is  monitoring
   according  to  its polling algorithm.  Multiple requests can
   be combined in a single message, but each request  is  still
   considered a separate poll.
   The  polled  machine  will  return  a  message of each  type
   requested;  it   will  only  answer  a poll with the correct
   system type and password. It will return  an  error  message
   (System  Type  1;  Message Type 2) if it receives a poll for
   the wrong system type or an unsupported message type.
   A polling message has the following form:
            1             0 0             0
            5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
           +---------------+---------------+
         0 | R-Message Type|   R-Subtype   |
         . +---------------+---------------+
         . :                               :\  additional
         . :                               : > message
           :                               :/  requests
           +---------------+---------------+

HMP FIELDS

System Type

   General Messages = 1

Message Type

   Polling Message = 1

Port Number

   Unused

Sequence Number

   The sequence number identifies the polling request.   An  HM
   will have separate sequences for each host it monitors.  The
   sequence number is returned in the response to a  poll;  the
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IEN-197 September 1981

   HM  will  use this information to associate polls with their
   responses and to determine round trip times.

Password

   The monitoring password.

POLL FIELDS

R-Message Type

   The message type requested.

R-Subtype

   Presently unused, this field might later be used to  specify
   options or include additional data in a polling message.
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IEN-197 September 1981

4.1.2 Message Type 2: Error in Poll

Description

   This message is sent  in  response  to  a  faulty  poll  and
   specifies the nature of the error.
   An error message has the following form:
            1             0 0             0
            5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
           +---------------+---------------+
         0 |          Error Type           |\  first
           +---------------+---------------+ > error
         1 | R-Message Type|   R-Subtype   |/  report
         . +---------------+---------------+
         . :                               :\  additional
         . :                               : > error
           :                               :/  reports
           +---------------+---------------+

HMP FIELDS

System Type

   General Messages = 1

Message Type

   Error Message = 2

Port Number

   Unused

Sequence Number

   A 16 bit number incremented each time an  error  message  is
   sent.

Returned Sequence Number

   The Sequence Number of the polling message which caused  the
   error.
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IEN-197 September 1981

ERROR MESSAGE FIELDS

Error Type

   This field specifies the nature of the error  in  the  poll.
   The following error types have been defined.
               1 = Reason unspecified.
               2 = Bad R-Message Type.
               3 = Bad R-Subtype.

R-Message Type R-Subtype

   These fields identify the poll request in error.
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IEN-197 September 1981

4.2 System Type 2: IMP

4.2.1 Message Type 1: IMP Trap

Description

   When a trap occurs, it is buffered in the IMP  and  sent  as
   soon  as possible.  Trap messages are unsolicited.  If traps
   happen in close sequence, several traps may be sent  in  one
   message.
   Through the use of sequence numbers, it will be possible  to
   determine   how  many  traps  are  being  lost.   If  it  is
   discovered that many are lost, a  polling  scheme  might  be
   implemented for traps.
   A IMP trap message has the following form:
                1             0 0             0
                5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
               +---------------+---------------+
             0 |       # of traps lost         |
               +---------------+---------------+
             1 :         first                 :
             . :             trap              :
             . :                 data          :
             . +---------------+---------------+
             . :         additional            :
             . :             trap              :
             . :                 data          :
               +---------------+---------------+

HMP Fields

System Type

   IMP = 2

Message Type

   IMP Trap Message = 1

Port Number

   Unused

Password

   Unused
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IEN-197 September 1981

Sequence Number

   A 16 bit number incremented each time a trap message is sent
   so  that  the  HM  can  order the received trap messages and
   detect missed messages.

IMP TRAP FIELDS

# of traps lost

   Under certain conditions, an IMP may overflow  its  internal
   trap  buffers  and  be  unable  to save traps to send.  This
   counter keeps track of such occurrences.

Trap Reports

   There can be several blocks of trap data  in  each  message.
   The format for each such block is below.
               +---------------+---------------+
               |             Size              |
               +---------------+---------------+
               |             Time              |
               +---------------+---------------+
               |            Trap ID            |
               +---------------+---------------+
               :             Trap              :
               :             Data              :
               +---------------+---------------+
Size
   Size is the number of 16 bit words in the trap, not counting
   the size field.
Time
   The time (in 640 ms. units)  at  which  the  trap  occurred.
   This  field  is  used to sequence the traps in a message and
   associate groups of traps.
Trap ID
   This is usually the program counter at  the  trap.   The  ID
   identifies  the  trap,  and  does  not  have to be a program
   counter, provided it uniquely identifies the trap.
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IEN-197 September 1981

Trap Data
   The IMP returns data giving more information about the trap.
   There are usually two entries: the values in the accumulator
   and the index register at the occurrence of the trap.
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4.2.2 Message Type 2: IMP status

Description

   The status message gives a quick summary of the state of the
   IMP.   Status  of the most important features of the IMP are
   reported  as  well  as  the  current  configuration  of  the
   machine.
   The format of the status message is as follows:
                1             0 0             0
                5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
               +---------------+---------------+
             0 |    Software Version Number    |
               +---------------+---------------+
               |       Last Trap Message       |
               +---------------+---------------+
               |    Hosts      |    Modems     |
               +---------------+---------------+
               |          Package bits         |
               +---------------+---------------+
               |          TIP version          |
               +---------------+---------------+
             5 |         restart/reload        |
               +---------------+---------------+
               |         Host                  |
               +                               +
               |             Test              |
               +                               +
               |                 Results       |
               +---------------+---------------+
               |                               |
               +          Crash                +
            10 |                               |
               +                Data           +
               |                               |
               +---------------+---------------+
               |           Anomalies           |
               +---------------+---------------+
            13 | HIHD0 | HIHD1 | HIHD2 | HIHD3 |
             . +---------------+---------------+
             . : HIHD4 | ...............       :
             . +---------------+---------------+
                           (cont.)
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IEN-197 September 1981

   Imp Status (cont.)
             . +---------------+---------------+
             . |        Modem                  |
             . +             State             +
             . |                  Data         |
             . +---------------+---------------+
             . :         Modem   State         :
             . :             Data......        :
               +---------------+---------------+

HMP FIELDS

System Type

   IMP = 2

Message Type

   IMP status message = 2

Port Number

   Unused

Sequence Number

   A 16 bit number incremented each time a  status  message  is
   sent.

Password

   The password contains the sequence  number  of  the  polling
   message to which this message responds.

IMP STATUS FIELDS

Software Version Number

   The IMP version number.

Last Trap Message

   Contains the sequence number of the last trap  message  sent
   to  the  HM.  This will allow the HM to detect how many trap
   messages are being lost.
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IEN-197 September 1981

Hosts

   The number of configured hosts in this system.

Modems

   The number of configured modems in this system.

Package Bits

   This is a bit encoded word that reports the set of  packages
   currently loaded in the system.  The table below defines the
   bits.
             Bit    Package
           (octal)
              1      VDH
              2      TIP
              4      experimental
             10      Cumulative Statistics
             20      Trace
             40      TTY
            100      DDT
            200      Store and Forward statistics
            400      End-to-end Statistics
           1000      Level measurements

TIP version

   The TIP version number if a TIP is loaded or zero if not.

Restart/Reload

   This word reports a restart or reload of an IMP.
         Value      Meaning
           1       restarted
           2       reloaded

Host Test Results

   These three words report the result of  the  host  test,  if
   any.   If a test is running, the first word will contain the
   host number, the second and third will contain the number of
   NOPs  sent  and  received,  respectively.   If  no  test  is
   running, the first word will contain a -1.

Crash Data

   Crash  data  reports  the   circumstances   surrounding   an
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IEN-197 September 1981

   unexpected  crash.   The  first word reports the location of
   the crash and the following two  are  the  contents  of  the
   accumulator and index registers.

Anomalies

   Anomalies is a collection of bit  flags  that  indicate  the
   state  of  various  switches or processes in the IMP.  These
   are  very  machine  dependent  and  only  a   representative
   sampling of bits is listed below.
             Bit       Meaning
           (octal)
              1      Sense Switch 1 ON
              2      Sense Switch 2 ON
              4      Sense Switch 3 ON
             10      Sense Switch 4 ON
             20      Override ON
            200      Trace ON
           2000      Message Generator ON

HIHD0 - HIHDn

   Each  four  bit  HIHD  field  gives   the   state   of   the
   corresponding host.
         Value   Meaning
           0       UP
           1       ready line down
           2       tardy
           3       non-existent
           4       VDH host not initialized

Modem State Data

   Modem state data contains four byte  fields  of  data.   The
   first  field indicates the line speed in a machine dependent
   fashion; the second field is the  number  of  line  protocol
   ticks  covered  by this report; the third is the neighbor on
   the line, and the fourth  is  a  count  of  missed  protocol
   packets over the interval specified in the second field.
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IEN-197 September 1981

4.2.3 Message Type 3: IMP Modem Throughput

Description

   The modem throughput message reports traffic statistics  for
   each modem in the system. The IMP will collect these data at
   regular intervals and save them awaiting a poll from the HM.
   If  a  period  is  missed  by the HM, the new results simply
   overwrite the old.  Two time stamps bracket  the  collection
   interval  (data-time  and prev-time) and are an indicator of
   missed reports.  In addition, mess-time indicates  the  time
   at which the message was sent.
   The modem throughput message will accommodate up to fourteen
   modems  in  one  packet.   A provision is made to split this
   into multiple packets by including a modem  number  for  the
   first  entry  in  the packet.  This field is not immediately
   useful, but if machine sizes grow beyond fourteen modems  or
   if  modem  statistics become more detailed and use more than
   three words per modem, this can be used to keep the  message
   within a single ARPANET packet.
   The format of the modem throughput message is as follows:
                1             0 0             0
                5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
               +---------------+---------------+
             0 |           Mess-Time           |
               +---------------+---------------+
               |    Software Version Number    |
               +---------------+---------------+
               |           Data-Time           |
               +---------------+---------------+
               |           Prev-Time           |
               +---------------+---------------+
               | Total  Modems |  This  Modem  |
               +---------------+---------------+
             5 |                               |
             . +             modem             +
             . |                               |
             . +           throughput          +
             . |                               |
             . +---------------+---------------+
             . :             modem             :
             . :                               :
             . :          throughput           :
               +---------------+---------------+
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IEN-197 September 1981

HMP FIELDS

System Type

   IMP = 2

Message Type

   IMP Modem Throughput message = 3

Port Number

   Unused

Sequence Number

   A 16 bit number  incremented  at  each  collection  interval
   (i.e.  when  a new throughput message is assembled).  The HM
   will be  able  to  detect  lost  or  duplicate  messages  by
   checking the sequence numbers.

Password

   The password contains the sequence  number  of  the  polling
   message to which this message responds.

IMP MODEM THROUGHPUT FIELDS

Mess-time

   The time (in 640ms. units) at which the message was sent  to
   the HM.

Software Version Number

   The IMP version number.

Data-Time

   Data-time is the time (in 640ms. units)  when  this  set  of
   data was collected.  (See Description.)

Prev-Time

   Prev-time is the time (in 640 ms.  units)  of  the  previous
   collection of data (and therefore, is the time when the data
   in this message began accumulating.)

Total Modems

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IEN-197 September 1981

   This is the number of modems in the system.

This Modem

   This Modem is the number of the first modem reported in this
   message.   Large  systems  that  are unable to fit all their
   modem reports into a single packet may  use  this  field  to
   separate their message into smaller chunks to take advantage
   of single packet message efficiencies.

Modem Throughput

   Modem  throughput  consists   of   three   words   of   data
   reporting  packets  and  words  output  on  each modem.  The
   first  word  counts packets  output and  the  following  two
   count  word  throughput.   The  double  precision  words are
   arranged high order first.  (Note  also that  messages  from
   Honeywell  type machines (316s, 516s and C30s) use a fifteen
   bit low order word.)  The first block reports output on  the
   modem  specified  by  "This  Modem".   The  following blocks
   report on consecutive modems.
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IEN-197 September 1981

4.2.4 Message Type 4: IMP Host Throughput

Description

   The host throughput message reports traffic  statistics  for
   each host in the system.  The IMP will collect these data at
   regular intervals and save them awaiting a poll from the HM.
   If  a  period  is  missed  by the HM, the new results simply
   overwrite the old.  Two time stamps bracket  the  collection
   interval  (data-time  and prev-time) and are an indicator of
   missed reports.  In addition, mess-time indicates  the  time
   at which the message was sent.
   The host throughput format will hold  only  three  hosts  if
   packet  boundaries are to be respected.  A provision is made
   to split this into multiple  packets  by  including  a  host
   number for the first entry in the packet.
   The format of the host throughput message is as follows:
                1             0 0             0
                5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
               +---------------+---------------+
             0 |           Mess-Time           |
               +---------------+---------------+
               |    Software Version Number    |
               +---------------+---------------+
               |           Data-Time           |
               +---------------+---------------+
               |           Prev-Time           |
               +---------------+---------------+
               |  Total Hosts  |   This  Host  |
               +---------------+---------------+
             5 :              host             :
             . :           throughput          :
               +---------------+---------------+

HMP FIELDS

System Type

   IMP = 2

Message Type

   IMP host Throughput message = 4

Port Number

   Unused
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Sequence Number

   A 16 bit number  incremented  at  each  collection  interval
   (i.e.  when  a new throughput message is assembled).  The HM
   will be  able  to  detect  lost  or  duplicate  messages  by
   checking the sequence numbers.

Password

   The password contains the sequence  number  of  the  polling
   message to which this message responds.

IMP HOST THROUGHPUT FIELDS

Mess-time

   The time (in 640ms. units) at which the message was sent  to
   the HM.

Software Version Number

   The IMP version number.

Data-Time

   Data-time is the time (in 640ms. units)  when  this  set  of
   data was collected.  (See Description.)

Prev-Time

   Prev-time is the time (in 640 ms.  units)  of  the  previous
   collection of data (and therefore, is the time when the data
   in this message began accumulating.)

Total Hosts

   The total number of hosts in this system.

This Host

   This host is the number of the first host reported  in  this
   message.   Large  systems  that  are unable to fit all their
   host reports into a single packet  may  use  this  field  to
   separate their message into smaller chunks to take advantage
   of single packet message efficiencies.
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Host Throughput

   Each host throughput block consists of twelve words  in  the
   following format:
               +---------------+---------------+
               |      messages to network      |
               +---------------+---------------+
               |     messages from network     |
               +---------------+---------------+
               |        packets to net         |
               +---------------+---------------+
               |       packets from net        |
               +---------------+---------------+
               |       messages to local       |
               +---------------+---------------+
               |      messages from local      |
               +---------------+---------------+
               |        packets to local       |
               +---------------+---------------+
               |       packets from local      |
               +---------------+---------------+
               |         words to imp          |
               |      (double precision)       |
               +---------------+---------------+
               |        words from imp         |
               |      (double precision)       |
               +---------------+---------------+
   Each host throughput message will contain several blocks  of
   data.   The  first  block  will  contain  data  for the host
   specified in  First  Host  Number.   Following  blocks  will
   contain data for consecutive hosts.  All counters are single
   precision with the exception of the two word counters  which
   are  double  precision.   The  double  precision  words  are
   arranged high order first.  Note  also  that  messages  from
   Honeywell  type machines (316s, 516s and C30s) use a fifteen
   bit low order word.
  1. 25-

IEN-197 September 1981

4.3 System Type 3: TAC

4.3.1 Message Type 1: TAC Trap Message

Description

   When a trap occurs, it is buffered in the TAC  and  sent  as
   soon  as possible.  Trap messages are unsolicited.  If traps
   happen in close sequence, several traps may be sent  in  one
   message.
   Through the use of sequence numbers, it will be possible  to
   determine   how  many  traps  are  being  lost.   If  it  is
   discovered that many are lost, a  polling  scheme  might  be
   implemented for traps.
   A TAC trap message has the following form:
                1             0 0             0
                5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
               +---------------+---------------+
             0 |       # of traps lost         |
               +---------------+---------------+
             1 :         first                 :
             . :             trap              :
             . :                 data          :
             . +---------------+---------------+
             . :         additional            :
             . :             trap              :
             . :                 data          :
               +---------------+---------------+

HMP FIELDS

System Type

   TAC = 3

Message Type

   TAC Trap Message = 1

Port Number

   Unused

Password or Returned Sequence Number

   Unused
  1. 26-

IEN-197 September 1981

Sequence Number

   A 16 bit number incremented each time a trap message is sent
   so  that  the  HM  can  order the received trap messages and
   detect missed messages.

TAC TRAP FIELDS

# of traps lost

   Under certain conditions, a TAC may  overflow  its  internal
   trap  buffers  and  be  unable  to save traps to send.  This
   counter keeps track of such occurrences.

Trap Reports

   There can be several blocks of trap data in each message.
   The format of the trap data is as follows:
               +---------------+---------------+
               |             Size              |
               +---------------+---------------+
               |             Time              |
               +---------------+---------------+
               |            Trap ID            |
               +---------------+---------------+
               :             Trap              :
               :             Data              :
               +---------------+---------------+
Size
   Size is the number of 16 bit words in the trap, not counting
   the size field.
Time
   The time (in 640ms. units) at which the trap occurred.  This
   field  is  used  to  sequence  the  traps  in  a message and
   associate groups of traps.
Trap ID
   This is (usually) the program counter at the trap.   The  ID
   identifies  the  trap,  and  does  not  have to be a program
   counter, provided that it uniquely identifies the trap.
  1. 27-

IEN-197 September 1981

Trap Data
   The TAC returns data giving more information about the trap.
   There are usually two entries: the values in the accumulator
   and the index register at the occurrence of the trap.
  1. 28-

IEN-197 September 1981

4.3.2 Message Type 2: TAC Status

Description

   The status message gives a quick summary of the state of the
   TAC.   Status  of the most important features of the TAC are
   reported  as  well  as  the  current  configuration  of  the
   machine.
   A TAC status message has the following form:
                1             0 0             0
                5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
               +---------------+---------------+
             0 |         Version Number        |
               +---------------+---------------+
               |       Last Trap Message       |
               +---------------+---------------+
               |           Bit Flags           |
               +---------------+---------------+
               |         Free PDB count        |
               +---------------+---------------+
               |         Free MBLK count       |
               +---------------+---------------+
             5 |      # of TCP connections     |
               +---------------+---------------+
               |      # of NCP connections     |
               +---------------+---------------+
               |         restart/reload        |
               +---------------+---------------+
               |                               |
               +          Crash                +
               |                               |
               +                Data           +
            10 |                               |
               +---------------+---------------+

HMP FIELDS

System Type

   TAC = 3

Message Type

   TAC Status Message = 2
  1. 29-

IEN-197 September 1981

Port Number

   Unused

Sequence Number

   A 16 bit number incremented each time a  status  message  is
   sent.

Returned Sequence Number

   Contains  the  sequence  number  from  the  polling  message
   requesting this report.

TAC STATUS FIELDS

Version Number

   The TAC's software version number.

Last Trap Message

   Contains the sequence number of the last trap  message  sent
   to  the  HM.  This will allow the HM to detect how many trap
   messages are being lost.

Bit Flags

   There are sixteen bit  flags  available  for  reporting  the
   state  of  various  switches  (hardware and software) in the
   TAC.  The bits are numbered as follows for purposes  of  the
   discussion below.
               1         1   0 0             0
               5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              | | | | | | | | | | | | | | | | |
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        The bit flags report the status of the following:
        Bit         Meaning
        0           0 => DDT override off; 1 => override on.
        1-4         0 => Sense Switch n is off; 1 => SSn on.
        5           0 => Extended DDT not enabled;
                      1 => Extended DDT enabled.
        6           0 => Traps going to console;
                      1 => Traps going to remote monitor.
        7-15        unused
  1. 30-

IEN-197 September 1981

Free PDB count

   The number of PDBs on the free queue.

Free MBLK count

   The number of MBLKs on the free queue.

# of TCP connections # of NCP connections

   The number of open connections for each protocol.

Restart/Reload

   This word reports a restart or reload of the TAC
         Value      Meaning
           1       restarted
           2       reloaded

Crash Data

   Crash  data  reports  the   circumstances   surrounding   an
   unexpected  crash.   The  first word reports the location of
   the crash and the following two  are  the  contents  of  the
   accumulator and index registers.
  1. 31-

IEN-197 September 1981

4.3.3 Message Type 3: TAC Throughput

Description

   The  TAC  throughput  message  reports  statistics  for  the
   various modules of the TAC.  The TAC will collect these data
   at regular intervals and save them awaiting a poll from  the
   HM.  If a period is missed by the HM, the new results simply
   overwrite the old.  Two time stamps bracket  the  collection
   interval  (data-time  and prev-time) and are an indicator of
   missed reports.  In addition, mess-time indicates  the  time
   at which the message was sent.
   A TAC throughput message has the following form:
             1             0 0             0
             5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
            +---------------+---------------+
          0 |           Mess-Time           |
            +---------------+---------------+
            |           Data-Time           |
            +---------------+---------------+
            |           Prev-Time           |
            +---------------+---------------+
            |         Version Number        |
            +---------------+---------------+
            |       Last Trap Message       |
            +---------------+---------------+
          5 |           Bit Flags           |
            +---------------+---------------+
            |         Free PDB count        |
            +---------------+---------------+
            |         Free MBLK count       |
            +---------------+---------------+
            |      # of TCP connections     |
            +---------------+---------------+
            |      # of NCP connections     |
            +---------------+---------------+ ----
         10 |     Host Input Throughput     |    ^
            +---------------+---------------+    |
            |     Host Input Abort Count    |    |
            +---------------+---------------+    |
            |    Host Input Garbled Count   |    |
            +---------------+---------------+    |
            |    Host Output Throughput     | 1822 info.
            +---------------+---------------+    |
                          (continued)
  1. 32-

IEN-197 September 1981

   TAC throughput (cont.)
            +---------------+---------------+    |
            |    Host Output Abort Count    | 1822 info.
            +---------------+---------------+    |
         15 |        Host Down Count        |    v
            +---------------+---------------+ ----
            |      # of datagrams sent      |    ^
            +---------------+---------------+    |
            |    # of datagrams received    |    |
            +---------------+---------------+  IP info.
            |    # of datagrams discarded   |    |
            +---------------+---------------+    |
            |    # of fragments received    |    v
            +---------------+---------------+ ----
         20 |      # of segments sent       |    ^
            +---------------+---------------+    |
            |    # of segments received     |    |
            +---------------+---------------+    |
            |    # of segments discarded    |    |
            +---------------+---------------+  TCP info.
            |       # of octets sent        |    |
            +---------------+---------------+    |
            |     # of octets received      |    |
            +---------------+---------------+    |
         25 |     # of retransmissions      |    v
            +---------------+---------------+ ----
            |      # of messages sent       |    ^
            +---------------+---------------+    |
            |    # of messages received     |    |
            +---------------+---------------+    |
            |    # of messages flushed      |    |
            +---------------+---------------+    |
            |        # of bytes sent        |    |
            +---------------+---------------+    |
         30 |      # of bytes received      |    |
            +---------------+---------------+   NCP info.
            |       # of ERRs received      |    |
            +---------------+---------------+    |
            |       # of RASs received      |    |
            +---------------+---------------+    |
            |       # of RAPs received      |    |
            +---------------+---------------+    |
            |       # of NXSs received      |    |
            +---------------+---------------+    |
         35 |       # of NXRs received      |    |
            +---------------+---------------+    |
            |       # of RSTs received      |    v
            +---------------+---------------+ ----
  1. 33-

IEN-197 September 1981

HMP FIELDS

System Type

   TAC = 3

Message Type

   TAC Throughput Message = 3

Port Number

   Unused

Sequence Number

   A 16 bit number  incremented  at  each  collection  interval
   (i.e.  when  a new throughput message is assembled).  The HM
   will be  able  to  detect  lost  or  duplicate  messages  by
   checking the sequence numbers.

Returned Sequence Number

   Contains  the  sequence  number  from  the  polling  message
   requesting this report.

TAC THROUGHPUT FIELDS

Mess-time

   The time (in 640ms. units) at which the message was sent  to
   the HM.

Data-Time

   Data-time is the time (in 640ms. units)  when  this  set  of
   data was collected.  (See Description.)

Prev-Time

   Prev-time is the time (in 640 ms.  units)  of  the  previous
   collection of data (and therefore, is the time when the data
   in this message began accumulating.)

Version Number

   The TAC's software version number.
  1. 34-

IEN-197 September 1981

Last Trap Message

   Contains the sequence number of the last trap  message  sent
   to  the  HM.  This will allow the HM to detect how many trap
   messages are being lost.

Bit Flags

   There are sixteen bit  flags  available  for  reporting  the
   state  of  various  switches  (hardware and software) in the
   TAC.  The bits are numbered as follows for purposes  of  the
   discussion below.
               1         1   0 0             0
               5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              | | | | | | | | | | | | | | | | |
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        The bit flags report the status of the following:
        Bit         Meaning
        0           0 => DDT override off; 1 => override on.
        1-4         0 => Sense Switch n is off; 1 => SSn on.
        5           0 => Extended DDT not enabled;
                      1 => Extended DDT enabled.
        6           0 => Traps going to console;
                      1 => Traps going to remote monitor.
        7-15        unused

Free PDB count

   The number of PDBs on the free queue.

Free MBLK count

   The number of MBLKs on the free queue.

# of TCP connections # of NCP connections

   The number of open connections for each protocol.
  1. 35-

IEN-197 September 1981

1822 info.

   These  six  fields  report  statistics  which  concern   the
   operation  of  the  1822 protocol module, i.e. the interface
   between the TAC and its IMP.

IP info.

   These four fields report statistics which  concern  Internet
   Protocol in the TAC.

TCP info.

   These  six  fields  report  statistics  which  concern   TCP
   protocol in the TAC.

NCP info.

   These eleven fields  report  statistics  which  concern  NCP
   protocol in the TAC.
  1. 36-
/data/webs/external/dokuwiki/data/pages/rfc/ien/ien197.txt · Last modified: 2001/06/25 21:01 by 127.0.0.1

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