



                            RFC - 869






                   A Host Monitoring Protocol















                        Robert M. Hinden





                 BBN Communications Corporation





                          December 1983














RFC-869                                             December 1983



                        Table of Contents





1   Introduction.......................................... 1

2   General Description................................... 3

3   Relationship to Other Protocols....................... 6

4   Protocol Operation.................................... 7

5   Header Formats....................................... 12
5.1   IP Headers......................................... 12
5.2   HMP Header......................................... 13

6   HMP Monitoring Center Message Formats................ 16
6.1   Message Type 100: Polling Message.................. 16
6.2   Message Type 101: Error in Poll.................... 18
6.3   Message Type 102: Control acknowledgment........... 20

A   Appendix A - IMP Monitoring.......................... 21
A.1   Message Type 1: IMP Trap........................... 21
A.2   Message Type 2: IMP status......................... 24
A.3   Message Type 3: IMP Modem Throughput............... 29
A.4   Message Type 4: IMP Host Throughput................ 32

B   Appendix B - TAC Monitoring.......................... 35
B.1   Message Type 1: TAC Trap Message................... 35
B.2   Message Type 2: TAC Status......................... 38
B.3   Message Type 3: TAC Throughput..................... 42

C   Appendix C - Gateway Monitoring...................... 47
C.1   Gateway Parameters................................. 47
C.2   Message Type 1: Gateway Trap....................... 48
C.3   Message Type 2: Gateway Status..................... 51
C.4   Message Type 3: Gateway Throughput................. 58
C.5   Message Type 4: Gateway Host Traffic Matrix........ 64
C.6   Message Type 6: Gateway Routing.................... 67










                               -i-


RFC-869                                             December 1983
Replaces IEN-197


                   A Host Monitoring Protocol





1  Introduction


     The Host Monitoring   Protocol  (HMP)  is  used  to  collect

information  from  hosts   in   various   networks.    A  host is

defined as an addressable  Internet  entity  that  can  send  and

receive  messages;  this  includes  hosts  such  as server hosts,

personal work stations, terminal concentrators, packet  switches,

and  gateways.  At present  the Host Monitoring Protocol is being

used to collect information from Internet Gateways and TACs,  and

implementations  are  being  designed  for  other  hosts.   It is

designed to monitor hosts spread over the  internet  as  well  as

hosts in a single network.


     This document is organized into three parts.  Section 2  and

3  contains a general description of the Host Monitoring protocol

and its relationship to other  protocols.   Section  4  describes

how  it  operates.   Section 5 and 6 contain the descriptions and

formats of the HMP messages.  These are  followed  by  appendices

containing the formats of messages sent by some of the hosts that

use the HMP  to  collect  their  monitoring  information.   These

appendicies included as examples only and are not part of the HMP

protocol.




                               -1-


RFC-869                                             December 1983



     This document replaces the previous HMP document "IEN-197, A

Host Monitoring Protocol."
















































                               -2-


RFC-869                                             December 1983



2  General Description


     The  Host  Monitoring  Protocol  is  a  transaction-oriented

(i.e.,  connection-less)  transport protocol.  It was designed to

facilitate  certain  simple  interactions  between  two  internet

entities,  one  of which may be considered to be "monitoring" the

other.  (In discussing the protocol we will sometimes speak of  a

"monitoring host" and a "monitored entity".)  HMP was intended to

be a useful transport protocol for applications that involve  any

or all of the following three different kinds of interactions:


   - The monitored entity sometimes  needs  to  send  unsolicited
     datagrams  to  the  monitoring  host.   The  monitoring host
     should be able to tell  when  messages  from  the  monitored
     entity  have  been lost in transit, and it should be able to
     determine the order in which the messages were sent, but the
     application  does  not require that all messages be received
     or that they be received strictly in the  same  sequence  in
     which they were sent.

   - The monitoring host needs to gather data from the  monitored
     entity by using a query-response protocol at the application
     level.  It is important to be able to determine which  query
     is being answered by a particular response, and to determine
     whether successive  responses  are  duplicates  of  previous
     ones.

   - The monitoring host must be able to initiate certain control
     functions  in  the  monitored entity, possibly including the
     setting  of  parameters  in  the  monitored   entity.    The
     monitoring  host  needs  to know if the control function has
     been carried out.


     In addition, we assume that a given monitoring host  may  be

monitoring  several  different  types of entities simultaneously,

and may be gathering several different types of data from a given



                               -3-


RFC-869                                             December 1983



type of monitored entity.  Several different monitoring hosts may

be monitoring a given entity, and several processes on  the  same

host may even be monitoring the same entity.


     Messages from the monitoring host to  the  monitored  entity

are  called  "polls".  They need to contain enough information to

allow the monitored entity to make the following determinations:


   - The monitored entity must be able  to  determine  that  this
     message  is  in  fact  a  poll  from a monitoring host.  The
     "system type," "message type," and "password" fields in  the
     HMP header have been defined to meet this need.

   - The monitored entity may need to be  able  to  identify  the
     particular  process  on  the  monitoring host that sent this
     poll, so it can send its response back to the right process.
     The  "port  number" field in the HMP header has been defined
     to meet this need.

   - The monitored  entity  must  be  able  to  indicate  to  the
     monitoring  host,  in its response, precisely which query is
     being answered by  a  particular  response.   The  "sequence
     number field" has been defined to meet this need.

   - The monitored entity must be able  to  determine  just  what
     kind  of action the monitoring host is requesting.  That is,
     the  HMP  transport  protocol  must  provide  some  way   of
     multiplexing  and  demultiplexing  the  various higher-level
     applications which use it.  The  "R-message  type"  and  "R-
     subtype"  fields of the polling message have been defined to
     meet this need.


     Messages from the monitored entity to  the  monitoring  host

need  to contain enough information to enable the monitoring host

to make the following determination:


   - The monitoring host must be able to route  this  message  to
     the  correct  process.   The  "port number" field meets this
     need.


                               -4-


RFC-869                                             December 1983



   - The monitoring host  must  be  able  to  match  up  received
     messages  with  the  polls, if any, that elicited them.  The
     "returned sequence number" field in the HMP header has  been
     defined to meet this need.

   - The monitoring host must be able to determine  which  higher
     level  application should receive a particular message.  The
     "system type" and "message type" fields are  used  for  this
     purpose.

   - The monitoring host must be able to determine  whether  some
     messages  of  a given type were lost in transit, and whether
     messages  have  arrived  out  of  sequence.   Although  this
     function,  strictly speaking, belongs to the application and
     not to the  transport  layer,  the  HMP  header  contains  a
     "sequence number" for this purpose.


     In addition, a simple one's complement checksum is  provided

in the HMP header to detect data corruption during transmission.






























                               -5-


RFC-869                                             December 1983



3  Relationship to Other Protocols


     The  Host  Monitoring  Protocol  is  a  transport   protocol

designed  to  fit into the layered internet protocol environment.

It operates on  top  of  the  Internet/ICMP  protocol  and  under

applications  that  require  its  services.  This relationship is

illustrated in the following diagram:


     +------+    +------+  +-------+      +------+
     |TELNET| ...|  FTP |  |GATEWAY|  ... | TAC  |   Application Layer
     +------+    +------+  +-------+      +------+
        |          |           |             |
        |          |           |             |
        |__________|           |_____________|
              |                       |
           +------+               +-------+
           |  TCP |               |  HMP  |          Transport Layer
           +------+               +-------+
              |                       |
              |                       |
           +-------------------------------------+
           |    Internet Protocol & ICMP         |   Internetwork Layer
           +-------------------------------------+
                              |
                  +------------------------+
                  | Local Network Protocol |         Network Layer
                  +------------------------+


If internetwork services are not required it should  be  possible

to  run  the HMP without an Internetwork layer.  As long as HMPs'

service requirnments (addressing,  protocol  demultiplexing,  and

occasional  delivery)  are  met  it  should run over a variety of

protocols.







                               -6-


RFC-869                                             December 1983



4  Protocol Operation


     The  HMP  is  built  around  the  idea  that  most  of   the

intelligence  needed  to  monitor  a  host  should  reside  in  a

monitoring center, not in the host.  The host should be  required

only to collect data and send it to the monitoring center, either

spontaneously or on request from the monitoring center.  The host

is  not  responsible  for insuring that the data arrives reliably

(except that it checksums  the  data);  instead,  the  monitoring

center  is  responsible for ensuring that the data it requests is

received correctly.


     Consequently,  the  HMP  is  based  on  polling  hosts   for

messages.   When the monitoring center requires a particular type

of data (e.g., throughput data), it sends  a  poll  to  the  host

requesting  that  type  of  report.  The host, upon receiving the

poll, responds with its latest set of  collected  data.   If  the

host  finds that the poll is incorrect (e.g., if the poll was for

throughput data and the host is not collecting throughput  data),

it responds with an error message.  The monitoring center waits a

reasonable length of time for the host to answer its poll.  If no

response  is  received,  it sends another poll for the same data.

In this way, if either a  poll  or  the  response  is  lost,  the

correct data is still collected.






                               -7-


RFC-869                                             December 1983



     The HMP is used to collect three different classes of data:


     o  Spontaneous Events (or Traps)

     o  Current status

     o  Statistical data collected over time


These classes of data allow a host to send data in a manner  best

suited  to  the  data.  For instance, the host may quickly inform

the monitoring center that a particular  event  has  happened  by

sending  a  trap message, while the monitoring center is reliably

collecting the host's throughput and accounting data.


     Traps report spontaneous  events,  as  they  occur,  to  the

monitoring center.  In order to insure their prompt delivery, the

traps are  sent  as  datagrams  with  no  reliability  mechanisms

(except  checksums)  such as acknowledgments and retransmissions.

Trap messages usually contain an  identifier  to  indicate  which

event  is  being  reported,  the  local time in the host that the

event occured, and data pertinent to the event.  The data portion

is intended to be host and event specific.


     Status information, the second type of data collected by the

Host Monitoring Protocol describes the current state of the host.

Status information is useful at one point, but it does  not  have

to be collected cumulatively over a certain period of time.  Only

the latest status is of interest; old status provides  no  useful

information.   The  monitoring center collects status information


                               -8-


RFC-869                                             December 1983



by sending a poll for status to a host.  Upon receiving the poll,

the  host  responds  with  its  latest status information, always

creating a new status message.  If the monitoring center does not

receive  a  response  to  its  poll,  it sends another poll.  The

monitoring center can decide if the host is up or down  based  on

whether the host responds to its polls.


     The third type of data collected by the HMP  is  statistical

data.  These are measurements taken over time, such as the number

of packets sent or received by a host and the  count  of  packets

dropped  for  a  particular reason.  It is important that none of

this type of data be lost.  Statistical data is  collected  in  a

host  over  a  time  interval.  When the collection time interval

expires, the current data is copied  to  another  area,  and  the

counters  are cleared.  The copied data is sent to the monitoring

center when the  host  receives  a  poll  requesting  statistical

information.   If  another poll is received before the collection

time interval has expired, the data in the buffer is sent  again.

The  monitoring center can detect duplicate messages by using the

sequence number in the header of the message, since each type  of

statistical data has its own sequence number counter.


     The collection frequency  for  statistics  messages  from  a

particular  host  must be relatively long compared to the average

round trip message time between the monitoring  center  and  that

host inorder to allow the monitoring center to re-poll if it does


                               -9-


RFC-869                                             December 1983



not receive an answer.   With  this  restriction,  it  should  be

possible   to   avoid  missing  any  statistics  messages.   Each

statistics message contains a field giving the  local  time  when

the  data  was  collected  and  the time at which the message was

sent.  This information allows the monitoring center to  schedule

when  it sends a poll so that the poll arrives near the beginning

of each collection period.  This ensures that  if  a  message  is

lost,  the  monitoring  center  will have sufficient time to poll

again for the statistics message for that period.


     The HMP also includes a provision to send data to  and  read

parameters  in  hosts.   The  data may be used to set switches or

interval timers used to control measurements in  a  host,  or  to

control  the  host itself (e.g. a restart switch).  The format of

the data and parameters is host specific.


     To send data to a host, the monitoring center sends the host

a  poll  for a control-acknowledgment message.  This poll message

includes the type of the data and the data being sent.  When  the

host  receives this poll, it processes the data and responds with

a control-acknowledgment message.


     To read parameters in a host,  the  monitoring  center  will

send  a  poll for parameters to the host.  This poll includes the

type of the parameters being read.  When the host  receives  this

poll,  it  will  send the parameters of the requested type to the



                              -10-


RFC-869                                             December 1983



monitoring center in a parameters message.


















































                              -11-


RFC-869                                             December 1983



5  Header Formats


     Host Monitor Protocol messages have the following format:

                    +----------------+
                    |  Local Network |
                    |    Header(s)   |
                    +----------------+
                    |  IP header     |
                    +----------------+
                    |      HMP       |
                    |     Header     |
                    |                |
                    +----------------+
                    |    D           |
                    |      A         |
                    |        T       |
                    |          A     |
                    +----------------+
                    |  Padding       |
                    +----------------+





5.1  IP Headers

HMP messages are sent using the version 4 IP header as  described
in  RFC-791  "Internet  Protocol."  The HMP protocol number is 20
(decimal).  The time to live field should be set to a  reasonable
value for the hosts being monitored.

All other fields should be set as specified in RFC-791.
















                              -12-


RFC-869                                             December 1983



5.2  HMP Header

The HMP header format is:

                  0             0 0             1
                  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
                 +---------------+---------------+
               0 |  System Type  | Message Type  |
                 +---------------+---------------+
               1 |  Port Number  | Control Flag  |
                 +---------------+---------------+
               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        | Monitoring Host
                       2        | IMP
                       3        | TAC
                       4        | Gateway
                       5        | SIMP
                       6        | BBN VAX/C70 TCP
                       7        | PAD
                       8        | Reserved
                       9        | TIU
                       10       | FEP
                       11       | Cronus Host
                       12       | Cronus MCS








                              -13-


RFC-869                                             December 1983



     Message types are defined and  used  for  each  system  type
     according  to  the  needs of that system.  The message types
     currently defined are:



                    Type   | Description
                 ----------+--------------------------
                           |
                    1      | Trap
                    2      | Status
                    3      | Thruput
                    4      | HTM - Host Traffic Matrix
                    5      | Parameters
                    6      | Routing
                    7      | Call Accounting
                           |
                    100    | Poll
                    101    | Error
                    102    | Control Acknowledgment




Port Number

     This field can be used to multiplex similar messages to/from
     different processes in one host.  It is currently unused.

Control Flag

     This field is used to pass control  information.   Currently
     Bit  15  is  defined  as  the  "More bit" which is used in a
     message in responce to a poll to indicate that there is more
     data to poll for.

Sequence Number

     Every message contains  a  sequence  number.   The  sequence
     number  is incremented when each new message of that type is
     sent.

Password or Returned Sequence Number

     The  Password field of a polling message from an  monitoring
     center  contains a password to  verify  that the  monitoring
     center is  allowed  to  gather  information.   Responses  to
     polling   messages   copy   the  Sequence  Number  from  the
     polling  message   and  return  it   in   this   field   for


                              -14-


RFC-869                                             December 1983



     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.












































                              -15-


RFC-869                                             December 1983



6  HMP Monitoring Center Message Formats

6.1  Message Type 100: Polling Message

Description

     The monitoring center will send polls to  the  hosts  it  is
     monitoring  to  collect their monitoring data. When the host
     receives a poll it will  return   a   message  of  the  type
     requested.   It   will  only  answer a poll with the correct
     system type and password and will return  an  error  message
     (Message  Type  101)  if  it  receives  a poll for the wrong
     system type or an unsupported message type.

     The Poll message includes a  facility  to  send  data  to  a
     monitored host.  The poll message to send data consists of a
     poll  for  a  Control  Acknowledgment  message  (type   102)
     followed  by  the data.  The R-Subtype specifies the type of
     the data that  is  being  sent.   When  the  monitored  host
     receives  a  Poll for a Control acknowledgment, it processes
     the data, and then responds with an  Control  acknowledgment
     message.  If the monitored host can not process the data, it
     should respond with an error message.

     A poll to read parameters consists a poll for  a  Parameters
     message.   The  R-Subtype  specifies  the type of parameters
     being read.  When the monitored host receives a poll  for  a
     Parameters  message,  it  responds with a Parameters message
     containing the requested information.

     A polling message has the following form:

              0             0 0             1
              0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
             +---------------+---------------+
           0 | R-Message Type|   R-Subtype   |
             +---------------+---------------+

             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           1 |             Data              |
             +                               +
           2 |                               |
             +                               +
             .                               .
             .                               .
           n |                               |
             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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RFC-869                                             December 1983



HMP FIELDS

System Type

     The type of machine being polled.

Message Type

     Polling Message = 100

Port Number

     Unused

Control Flag

     Unused

Sequence Number

     The sequence number identifies  the  polling  request.   The
     Monitoring  Center  will  maintain separate sequence numbers
     for each host it monitors.  This sequence number is returned
     in the response to a poll and the monitoring center 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

     This field is used when sending data and reading  parameters
     and  it  specifies  the  type  of  the  data  being  sent or
     parameters being read.

Data

     When  the  poll  is  requesting  a  Control   Acknowledgment
     message,  data  is included in the poll message.  A poll for
     any other type of message does not include any data  .   The
     contents of the data is host specific.


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RFC-869                                             December 1983



6.2  Message Type 101: 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:

              0             0 0             1
              0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
             +---------------+---------------+
           0 |          Error Type           |
             +---------------+---------------+
           1 | R-Message Type|   R-Subtype   |
             +---------------+---------------+

HMP FIELDS

System Type

     The type of machine sending message.

Message Type

     Error Message = 101

Port Number

     Unused

Control Flag

     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.







                              -18-


RFC-869                                             December 1983



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.
                 4 = Unknown parameter
                 5 = Invalid parameter value
                 6 = Invalid parameter/value format
                 7 = Machine in Loader

R-Message Type
R-Subtype

     These fields identify the poll request in error.































                              -19-


RFC-869                                             December 1983



6.3  Message Type 102: Control acknowledgment

Description

     This message is sent in response to a poll for this type  of
     message.   It  is used to acknowledge poll messages that are
     used to set parameters in the monitored host.

     The Control acknowledgment has no fields other than the  HMP
     header.

HMP FIELDS

System Type

     The type of the system sending the message.

Message Type

     Control acknowledgment = 102

Port Number

     Unused

Control Flag

     Unused

Sequence Number

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

Returned Sequence Number

     The Sequence Number of the polling message  which  requested
     this message.













                              -20-


RFC-869                                             December 1983



A  Appendix A - IMP Monitoring

A.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:

                  0             0 0             1
                  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
                 +---------------+---------------+
               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





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RFC-869                                             December 1983



Control Flag

     Unused

Password

     Unused

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.


                              -22-


RFC-869                                             December 1983



     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.

  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.





































                              -23-


RFC-869                                             December 1983



A.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:

                  0             0 0             1
                  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
                 +---------------+---------------+
               0 |    Software Version Number    |
                 +---------------+---------------+
                 |       Last Trap Message       |
                 +---------------+---------------+
                 | Max # Hosts   | Max # Modems  |
                 +---------------+---------------+
                 | Max # Channels|  Max # IMPs   |
                 +---------------+---------------+
                 |      Package bits 0-15.       |
                 +---------------+---------------+
               5 |      Package bits 16.-31.     |
                 +---------------+---------------+
                 |                               |
                 +          Crash                +
                 |                               |
                 +                Data           +
                 |                               |
                 +---------------+---------------+
                 |           Anomalies           |
                 +---------------+---------------+
              10 |   Free Pool   |   S+F Pool    |
                 +---------------+---------------+
                 |Reassembly Pool| Allocated Pool|
                 +---------------+---------------+
                 | HIHD0 | HIHD1 | HIHD2 | HIHD3 |
               . +---------------+---------------+
               . : HIHD4 | ...............       :
               . +---------------+---------------+
                             (cont.)








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RFC-869                                             December 1983





     Imp Status (cont.)

               . +---------------+---------------+
               . |        Modem                  |
               . +             State             +
               . |                  Data         |
               . +---------------+---------------+
               . :         Modem   State         :
               . :             Data......        :
                 +---------------+---------------+



HMP FIELDS

System Type

     IMP = 2

Message Type

     IMP status message = 2

Port Number

     Unused

Control Flag

     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.



                              -25-


RFC-869                                             December 1983



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.

Hosts

     The number of configured hosts in this system.

Modems

     The number of configured modems in this system.

Channels

     The maximum possible number  of  IMP-IMP  channels  in  this
     system.

IMPs

     The maximum possible number of IMPs 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.























                              -26-


RFC-869                                             December 1983




                    Bit    Package
                 (octal)
                (1st Word)
                    1      VDH
                    2      Logical address tables
                    4      Mezmode
                   10      Cumulative Statistics
                   20      Trace
                   40      TTY
                  100      DDT
                  200      HDLC
                  400      HDH
                 1000      Cassette Writer
                 2000      Propagation Delay Measurement
                 4000      X25
                10000      Profile Measurements
                20000      Self Authenticating Password
                40000      Host traffic Matrix
               100000      Experimental/Special

                (2nd Word)
                    1      End-to-end Statistics
                    2      Store and Forward statistics

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.

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)
               20      Override ON
              200      Trace ON
             1000      Statistics ON
             2000      Message Generator ON
             4000      Packet Trace ON
            10000      Host Data Checksum is BAD
            20000      Reload Location SET



                              -27-


RFC-869                                             December 1983



Buffer Pool Counts

     These are four bytes  of  counters  indicating  the  current
     usage  of  buffers in the IMP.   The four counters are: free
     buffers, store-and-forward buffers, reassembly  buffers  and
     allocated buffers.

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



Modem State Data

     Modem state data contains six  fields  of  data  distributed
     over  four  words.   The  first field (4 bits) indicates the
     line speed; the second field (4 bits) is the number  of  the
     modem  that is used by the neighboring IMP on this line; the
     third field (8 bits) is the number of  line  protocol  ticks
     covered  by  this  report; the fourth (1 bit) indicates line
     down(1) or up(0); the fifth (7 bits) is the  IMP  number  of
     neighbor  IMP on the line; and the sixth (8 bits) is a count
     of missed protocol packets over the  interval  specified  in
     the third field.



















                              -28-


RFC-869                                             December 1983



A.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:

                  0             0 0             1
                  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
                 +---------------+---------------+
               0 |           Mess-Time           |
                 +---------------+---------------+
                 |    Software Version Number    |
                 +---------------+---------------+
                 |           Data-Time           |
                 +---------------+---------------+
                 |           Prev-Time           |
                 +---------------+---------------+
                 | Total  Modems |  This  Modem  |
                 +---------------+---------------+
               5 |                               |
               . +             modem             +
               . |                               |
               . +           throughput          +
               . |                               |
               . +---------------+---------------+
               . :             modem             :
               . :                               :
               . :          throughput           :
                 +---------------+---------------+




                              -29-


RFC-869                                             December 1983



HMP FIELDS


System Type

     IMP = 2

Message Type

     IMP Modem Throughput message = 3

Port Number

     Unused

Control Flag

     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.)





                              -30-


RFC-869                                             December 1983



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

     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.






















                              -31-


RFC-869                                             December 1983



A.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:

                  0             0 0             1
                  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
                 +---------------+---------------+
               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





                              -32-


RFC-869                                             December 1983



Port Number

     Unused

Control Flag

     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 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


                              -33-


RFC-869                                             December 1983



     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.

Host Throughput

     Each host throughput block consists of eight  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      |
                 +---------------+---------------+

     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.


















                              -34-


RFC-869                                             December 1983



B  Appendix B - TAC Monitoring

B.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:

                  0             0 0             1
                  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
                 +---------------+---------------+
               0 |           Version #           |
                 +---------------+---------------+
               1 :         first                 :
               . :             trap              :
               . :                 data          :
               . +---------------+---------------+
               . :         additional            :
               . :             trap              :
               . :                 data          :
                 +---------------+---------------+


HMP FIELDS

System Type

     TAC = 3

Message Type

     TAC Trap Message = 1

Port Number

     Unused





                              -35-


RFC-869                                             December 1983



Control Flag

     Unused

Password or Returned Sequence Number

     Unused

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

Version #

     The version # of the TAC Software.

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              :
                 +---------------+---------------+
                 |            Count              |
                 +-------------------------------+

  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


                              -36-


RFC-869                                             December 1983



     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.

  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.

  Count

     The TAC Counts repetitions of the same trap ID  and  reports
     this count here.

































                              -37-


RFC-869                                             December 1983



B.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:


                  0             0 0             1
                  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
                  ---------------+---------------+
               0 |         Version Number        |
                 +---------------+---------------+
                 |       Last Trap Message       |
                 +---------------+---------------+
                 |           Bit Flags           |
                 +---------------+---------------+
                 |         Free PDB count        |
                 +---------------+---------------+
                 |         Free MBLK count       |
                 +---------------+---------------+
               5 |      # of TCP connections     |
                 +---------------+---------------+
                 |      # of NCP connections     |
                 +---------------+---------------+
                 |         INA A Register        |
                 +---------------+---------------+
                 |         INA X Register        |
                 +---------------+---------------+
                 |         INA B Register        |
                 +---------------+---------------+
              l0 |         restart/reload        |
                 +---------------+---------------+
                 |                               |
                 +          Crash                +
                 |                               |
                 +                Data           +
              13 |                               |
                 +---------------+---------------+







                              -38-


RFC-869                                             December 1983



HMP FIELDS

System Type

     TAC = 3

Message Type

     TAC Status Message = 2

Port Number

     Unused

Control Flag

     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.












                              -39-


RFC-869                                             December 1983



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.


                 0             0 0             1
                 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                | | | | | | | | | | | | | | | | |
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          The bit flags report the status of the following:

          Bit         Meaning
          15          0 => DDT override off; 1 => override on.
          11-14       0 => Sense Switch n is off; 1 => SSn on.
          10          0 => Traps to remote monitor;
                      1 => Traps to console.
          9           1 => Message generator on.
          0-8         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.

INA Report

     These three fields report the values retained by an INA 1011
     instruction  in  a  C/30.  This  instruction  returns micro-
     machine status and  errors.   In  a  #316,  the  fields  are
     meaningless.








                              -40-


RFC-869                                             December 1983



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.




































                              -41-


RFC-869                                             December 1983



B.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:

               0             0 0             1
               0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
              +---------------+---------------+
            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)



                              -42-


RFC-869                                             December 1983




     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 fragments discarded   |    v
              +---------------+---------------+ ----
              |      # of segments sent       |    ^
              +---------------+---------------+    |
              |    # of segments received     |    |
              +---------------+---------------+    |
              |    # of segments discarded    |    |
              +---------------+---------------+  TCP info.
              |       # of octets sent        |    |
              +---------------+---------------+    |
           25 |     # of octets received      |    |
              +---------------+---------------+    |
              |     # of retransmissions      |    v
              +---------------+---------------+ ----


HMP FIELDS

System Type

     TAC = 3

Message Type

     TAC Throughput Message = 3

Port Number

     Unused

Control Flag

     Unused


                              -43-


RFC-869                                             December 1983



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.

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.





                              -44-


RFC-869                                             December 1983






                 0             0 0             1
                 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                | | | | | | | | | | | | | | | | |
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



          The bit flags report the status of the following:

          Bit         Meaning
          15          0 => DDT override off; 1 => override on.
          11-14       0 => Sense Switch n is off; 1 => SSn on.
          10          0 => Traps to remote monitor;
                      1 => Traps to console.
          9           1 => Message generator on.
          0-8         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.

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 five fields report statistics which  concern  Internet
     Protocol in the TAC.

TCP info.



                              -45-


RFC-869                                             December 1983



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

















































                              -46-


RFC-869                                             December 1983



C  Appendix C - Gateway Monitoring

C.1  Gateway Parameters

     The gateway supports parameters to set Throughput  and  Host
     traffic matrix measurements.  The type of parameters and the
     parameter and data pairs are as follows:

     Throughput - Type = 3


          Parm.  Description             Control Data Word
          -----  -----------             -----------------

          1      Start/Stop              0=Stop,1=Start
          2      Collection Interval     Time in 1 minute
                                         ticks


     Host Traffic Matrix - Type = 4


          Parm.  Description             Control Data Word
          -----  -----------             -----------------

          1      Start/Stop              0=Stop,1=Start
          2      Collection Interval     Time in 1 minute
                                         ticks
          3      HTM Switch Control      Include Control
                                         Protocols





















                              -47-


RFC-869                                             December 1983



C.2  Message Type 1: Gateway Trap

Description

     When traps occur in the gateway they  are  buffered.   At  a
     fixed  time interval (currently 10 seconds) the gateway will
     send any traps that are in  the  buffer  to  the  monitoring
     center.  The traps are sent as unsolicited messages.

     A Gateway trap message has the following format:

           0             0 0             1
           0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |      Gateway Version #        |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |    Size of Trap Entry         |       ;First Trap
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |       Time of Trap            |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |       Trap ID                 |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |       Process ID              |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |              R0               |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |              R1               |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |              R2               |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |              R3               |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    (continued)
















                              -48-


RFC-869                                             December 1983



Gateway Trap Message (cont'd.)


          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |              R4               |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |              R5               |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |              R6               |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |     Count of this Trap        |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                          .
                          .
                          .
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |                               |
          |    Additional Trap reports    |
          |                               |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

HMP FIELDS

System Type

     Gateway = 4

Message Type

     Gateway Trap Message = 1

Port Number

     Unused

Control Flag

     Unused

Password or Returned Sequence Number

     Unused

Sequence Number

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



                              -49-


RFC-869                                             December 1983



GATEWAY TRAP FIELDS

Gateway Version #

     The software version number of the gateway sending the trap.

Trap Reports

     The remainder of the  trap  message  consists  of  the  trap
     reports.  Each consists of the following fields:

     Size of Trap Entry

          The size  in  16-bit  words  of  the  trap  entry,  not
          including the size field.

     Time of Trap

          The time in (in 1/60 sec.  ticks)  at  which  the  trap
          occurred.

     Trap ID

          The number of the trap which is used  to  identify  the
          trap.

     Process ID

          The identifier of the process that executed the trap.

     R0-R6

          The registers of the machine at the occurrence  of  the
          trap.

     Count of this Trap

          The number of times that this trap occurred.













                              -50-


RFC-869                                             December 1983



C.3  Message Type 2: Gateway Status

Description

     The gateway status message gives a summary of the status  of
     the  gateway.  It reports information such as version number
     of the gateway, buffer memory usage,  interface  status  and
     neighbor gateway status.

     A Gateway Status message has the following format:









































                              -51-


RFC-869                                             December 1983




      0                   1         1         2                   3 3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Version Number        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Patch Version Number      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Time Since Gateway Restart   |       ;in minutes
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |       Measurement Flags       |       ; Bit flags to indicate which
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+       ; measurements are on, 1= On
     |      Routing Sequence No.     |       ; Sequence # of last routing
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+       ;   update sent
     |    Access Table Version #     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Load Sharing Table Ver. #    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Memory in Use         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Memory Idle           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Memory Free           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   # of Blks   |                       ; Memory Allocation Info
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Size of 1st Block (in bytes) |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  # Allocated  |
     +-+-+-+-+-+-+-+-+
     |    # Idle     |
     +-+-+-+-+-+-+-+-+
             .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Size of n'th Block (in bytes) |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  # Allocated  |
     +-+-+-+-+-+-+-+-+
     |    # Idle     |
     +-+-+-+-+-+-+-+-+
                  (continued)










                              -52-


RFC-869                                             December 1983



Gateway Status Message (cont'd.)

     +-+-+-+-+-+-+-+-+
     |   # of Ints.  |
     +-+-+-+-+-+-+-+-+
     | Int 1 Flags   |                       ;Interface 1 Status Flags
     +-+-+-+-+-+-+-+-+                       ; Bit 0 - 1=Up, 0=Down
                                             ;     1 - 1=Looped, 0=Not
     +-+-+-+-+-+-+-+-+
     | Buffers       |                       ; # of buffers on write Queue
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Time since last Status Change |       ;Time since last up/dwn change
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    # of Buffers Allocated     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Data Size for Interface    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Interface 1 Address                                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     .
                     .
     +---------------+
     | Int n Flags   |                       ;Interface n Status Flags
     +-+-+-+-+-+-+-+-+
     | Buffers       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Time since last Status Change |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    # of Buffers Allocated     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Data Size for Interface    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Interface n Address                                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | # Neighbors   |
     +-+-+-+-+-+-+-+-+
     | UP/DN Flags   |                       ;Bit flags for Up or Down
     +-+-+-+-+-+-+-+-+                       ; 0 = Dwn,  1 = Up
             .                               ; MSB is neighbor 1
             .                               ; (as many bytes as necessary)
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Neighbor 1 Address                                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     .
                     .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Neighbor n Address                                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                              -53-


RFC-869                                             December 1983



HMP FIELDS

System Type

     Gateway = 4

Message Type

     Gateway Status Message = 2

Port Number

     Unused

Control Flag

     Unused

Password or Returned Sequence Number

     Unused

Sequence Number

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

GATEWAY STATUS FIELDS

Version Number

     The  version  number  of  the  gateway  sending  the  Status
     message.

Patch Version Number

     The patch version number of the gateway.

Time Since Gateway Restart

     The time in minutes since the gateway was last restarted  or
     reloaded.








                              -54-


RFC-869                                             December 1983



Measurement Flags

     Flags that, if set, indicate which measurements  are  turned
     on.  Current values are:


          Bit 0   =   Message Generator
              1   =   Throughput
              2   =   Host Traffic Matrix
              3   =   Access Control 1
              4   =   Access Control 2
              5   =   Load Sharing
              6   =   EGP in Gateway


Routing Sequence Number

     The sequence number of the last routing update sent by  this
     gateway.

Access Control Table Version #

     The version number of the access control table.

Load Sharing Table Version #

     The version number of the load sharing table.

Memory In Use

     The number of bytes of buffer memory that are  currently  in
     use.

Memory Idle

     The  number  of  bytes  of  buffer  memory  that  have  been
     allocated but are currently idle.

Memory Free

     The number of bytes of  buffer  memory  that  has  not  been
     allocated.

MEMORY ALLOCATION INFORMATION

     The next part of the status message contains information  on
     the buffer pools in the gateway.    The fields are:

     # of Blocks


                              -55-


RFC-869                                             December 1983



          The number of different buffer pools.

     Size of Block

          The size of this block in bytes.

     # Allocated

          The number of  blocks  of  this  size  that  have  been
          allocated.

     # Idle

          The number of blocks of this size that are idle.

GATEWAY INTERFACE FIELDS

     The next part of the status message are fields that  provide
     information about the gateway's interfaces.  The fields are:

     # of Interfaces

          The number of network interfaces that the gateway has.

     Interface Flags

          Flags that indicate the status of this interface.   The
          current values are:

               Bit 0  -  1=Up/0=Down
                   1  -  1=Looped/0=Not Looped


     Buffers

          The numbers on this interfaces write queue.

     Time Since Last Status Change

          The time in minutes since this interface changed status
          (Up/Down).

     # of Buffers Allocated

          The number of buffers allocated for this interface.

     Data Size for Interface

          The buffer size required for this interface.


                              -56-


RFC-869                                             December 1983



     Interface Address

          The Internet address of this interface.

NEIGHBOR GATEWAY FIELDS

     The final part of the status message consists of information
     about this gateway's neighbor gateways.  The fields are:

     # of Neighbors

          The number of gateways that are  neighbor  gateways  to
          this gateway.

     UP/DN Flags

          Bit flags to indicate if the neighbor is up or down.

     Neighbor Address

          The Internet address of the neighbor gateway.






























                              -57-


RFC-869                                             December 1983



C.4  Message Type 3: Gateway Throughput

Description

     The gateway collects throughput statistics for the  gateway,
     its interfaces, and its neighbor gateways.  It collects them
     for regular intervals and will save them for collection  via
     a  Poll  message  from the Monitoring host.  If they are not
     collected by the end of the next interval, they will be lost
     because another copy will be put into the saved area.

     A Gateway Throughput message has the following format:

      0                   1         1         2                   3 3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Gateway Version Number    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Collection Time in Min    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |      Number of Interfaces     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |       Number of Neighbors     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Number of Host Unreachable   |       ; # of packets dropped because
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+       ;   Host was Unreachable
     |  Number of Net Unreachable    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+       ;   Net was Unreachable

     ; Interface Counters

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Interface Address                                            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Packets Dropped on Input    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Count of IP Errors        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Count of Datagrams for Us   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Datagrams to be Forwarded   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Count of Datagrams Looped   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             (continued)






                              -58-


RFC-869                                             December 1983



Gateway Throughput Message (cont'd.)

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Count of Bytes Input                                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Count of Datagrams From Us   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Count that were Forwarded     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Count of Local Net Dropped   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Count of Queue full Dropped  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Count of Bytes Output                                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     .
                     .
                     .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     |          Counters For Additional Interfaces                   |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     ; Neighbor counters

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Neighbor Address                                             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Count of Routing Updates TO   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |Count of Routing Updates FROM  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                              (continued)

















                              -59-


RFC-869                                             December 1983



Gateway Throughput Message (cont'd.)

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Pkts from US sent to/via Neig |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Pkts forwarded to/via Neighb |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Datagrams Local Net Dropped  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Datagrams Queue full Dropped  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Count of Bytes send to Neighbor                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     .
                     .
                     .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     |        Counters for Additional Neighbor Gateways              |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


HMP FIELDS

System Type

     Gateway = 4

Message Type

     Gateway Throughput Message = 3

Port Number

     Unused

Control Flag

     Unused

Password or Returned Sequence Number

     Unused

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


                              -60-


RFC-869                                             December 1983



     detect missed messages.

GATEWAY THROUGHPUT FIELDS

Gateway Version Number

     The software version number of the gateway sending the trap.

Collection Time in Min.

     The time period in minutes in which the throughput  data  is
     to be collected.

Number of Interfaces

     The number of interfaces this gateway has.

Number of Neighbors

     The number of neighbor gateways this gateway has.

Number of Host Unreachable

     The  number  of  packets  dropped  because  the   Host   was
     unreachable.

Number of Net Unreachable

     The number  of  packets  dropped  because  the  Network  was
     unreachable.

INTERFACE COUNTERS

     The next part of the Throughput  message  contains  counters
     for   the  gateways  interfaces.   Each  interface  has  the
     following fields:

     Interface Address

          The Internet address of this interface.

     Packets Dropped on Input

          The number  of  packets  on  input  to  this  interface
          because there were not enough buffers.

     Count of IP Errors

          The number of packets received with bad IP headers.


                              -61-


RFC-869                                             December 1983



     Count of Datagrams for Us

          The number of  datagrams  received  addressed  to  this
          gateway.

     Datagrams to be Forwarded

          The number of datagrams were not for this  gateway  and
          should be sent out another interface.

     Count of Datagrams Looped

          The number of datagrams that were received on and  sent
          out of this interface.

     Count of Bytes Input

          The number of bytes received on this interface.

     Count of Datagrams From Us

          The  number  of  datagrams  that  originated  at   this
          gateway.

     Count that were Forwarded

          The number of datagrams that were forwarded to  another
          gateway.

     Count of Local Net Dropped

          The number of packets  that  were  dropped  because  of
          local network flow control restrictions.

     Count of Queue full Dropped

          The number of packets that  were  dropped  because  the
          output queue was full.

     Count of Bytes Output

          The number of bytes sent out on this interface.









                              -62-


RFC-869                                             December 1983



NEIGHBOR COUNTERS

     The last part of the Throughput message are counts for  each
     neighbor gateway.  The fields are:

     Neighbor Address

          The Internet address of this neighbor gateway.

     Count of Routing Updates TO

          The number of routing updates  sent  to  this  neighbor
          gateway.

     Count of Routing Updates FROM

          The  number  of  routing  updates  received  from  this
          neighbor gateway.

     Pkts from US sent to/via Neig

          The number of packets from this gateway sent to or  via
          this neighbor gateway.

     Pkts forwarded to/via Neighb

          The number of packets forwarded to or via this neighbor
          gateway.

     Datagrams Local Net Dropped

          The  number  of  datagrams  dropped  to  this  neighbor
          gateway   because   of   local   network  flow  control
          restrictions.

     Datagrams Queue full Dropped

          The  number  of  datagrams  dropped  to  this  neighbor
          because the output queue was full.

     Count of Bytes send to Neighbor

          The number of bytes sent to this neighbor gateway.








                              -63-


RFC-869                                             December 1983



C.5  Message Type 4: Gateway Host Traffic Matrix

Description

     The Host Traffic Matrix (HTM) message  contains  information
     about  the  traffic  that  flows  through the gateway.  Each
     entry consists of the number of datagrams sent and  received
     for a particular source/destination pair.

     A Gateway HTM message has the following format:

      0                   1         1         2                   3 3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Gateway Version Number    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        Overflow counter       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Collection Time in Min    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Number of HTM entries     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    IP Source Address                                          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    IP Destination Address                                     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | IP Protocol   |  (unused)     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Counter for SRC -> DST datagrams                           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Counter for DST -> SRC datagrams                           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     .
                     .
                     .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     |      Additional HTM Reports                                   |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+









                              -64-


RFC-869                                             December 1983



HMP FIELDS

System Type

     Gateway = 4

Message Type

     Gateway HTM Message = 4

Port Number

     Unused

Control Flag

     Unused

Password or Returned Sequence Number

     Unused

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.

GATEWAY HTM FIELDS

Gateway Version Number

     The software version number of this gateway.

Overflow counter

     The number of HTM entries lost because the  HTM  buffer  was
     full.

Collection Time in Min

     The time period in minutes in which the HTM  data  is  being
     collected.

Number of HTM entries

     The number of HTM reports included in this message.




                              -65-


RFC-869                                             December 1983



HTM ENTRIES

     The remainder of the HTM message consists of the actual  HTM
     entries.  Each entry consists of the following fields:

     IP Source Address

          The source Internet  address  of  the  datagrams  being
          counted.

     IP Destination Address

          The destination Internet address of the datagrams being
          counted.

     IP Protocol

          The protocol number of the datagrams.

     Counter for SRC -> DST datagrams

          The  number  of  datagrams  sent  in  the   Source   to
          Destination address direction.

     Counter for DST -> SRC datagrams

          The number of datagrams  sent  in  the  Destination  to
          Source address direction.























                              -66-


RFC-869                                             December 1983



C.6  Message Type 6: Gateway Routing

Description

     The Routing message contains information  about  routes  the
     gateway  has  to the networks that make up the Internet.  It
     includes information about its interfaces and  its  neighbor
     gateways.

     A Gateway Routing message has the following format:

      0                   1         1         2                   3 3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Version Number        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   # of Ints.  |
     +-+-+-+-+-+-+-+-+
     | UP/DN Flags   |                       ;Bit flags for Up or Down
     +-+-+-+-+-+-+-+-+                       ; 0 = Dwn,  1 = Up
             .                               ; MSB is interface 1
             .                               ; (as many bytes as necessary)
             .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Interface 1 Address                                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     .
                     .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Interface n Address                                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | # Neighbors   |
     +-+-+-+-+-+-+-+-+
     | UP/DN Flags   |                       ;Bit flags for Up or Down
     +-+-+-+-+-+-+-+-+                       ; 0 = Dwn,  1 = Up
             .                               ; MSB is neighbor 1
             .                               ; (as many bytes as necessary)
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Neighbor 1 Address                                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     .
                     .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Neighbor n Address                                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         (continued)




                              -67-


RFC-869                                             December 1983



Gateway Routing Message (cont'd.)

     +-+-+-+-+-+-+-+-+
     | # of Networks |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Network 1 #   |               |               |  ; 1, 2, or 3 bytes
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Distance    |
     +-+-+-+-+-+-+-+-+
     |   Neighbor #  |
     +-+-+-+-+-+-+-+-+
                     .
                     .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Network n #   |               |               |  ; 1, 2, or 3 bytes
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Distance    |
     +-+-+-+-+-+-+-+-+
     |   Neighbor #  |
     +-+-+-+-+-+-+-+-+

HMP FIELDS

System Type

     Gateway = 4

Message Type

     Gateway Trap Message = 6

Port Number

     Unused

Control Flag

     Unused

Password or Returned Sequence Number

     Unused

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.



                              -68-


RFC-869                                             December 1983



GATEWAY ROUTING FIELDS

Gateway Version #

     The software version number of the gateway sending the trap.

INTERFACE FIELDS

     The first part of the routing message  contains  information
     about  the  gateway's  interfaces.   There  is data for each
     interface.  The fields are:

     # of Interfaces

          The number of interfaces that this gateway has.

     UP/DN Flags

          Bit flags to indicate if the Interface is up or down.

     Interface Address

          The Internet address of the Interface.

NEIGHBOR FIELDS

     The next part of the routing  message  contains  information
     about this gateway's neighbor gateways.  The fields are:

     # of Neighbors

          The number of gateways that are  neighbor  gateways  to
          this gateway.

     UP/DN Flags

          Bit flags to indicate if the neighbor is up or down.

     Neighbor Address

          The Internet address of the neighbor gateway.

NETWORK ROUTING FIELDS

     The last part of the routing  message  contains  information
     about   this  gateway's  routes  to  other  networks.   This
     includes the distance to each  network  and  which  neighbor
     gateway is the route to the network.  The fields are:



                              -69-


RFC-869                                             December 1983



     # of Networks

          The number of networks that  are  reachable  from  this
          gateway.

     Network #

          The network  number  of  this  network.   This  is  the
          network  part  of  the Internet address and may be one,
          two, or three bytes in length depending on  whether  it
          is a Class A, B, or C address.

     Distance

          The distance in hops to this network.  Zero hops  means
          that the network is directly connected to this gateway.
          A negative number means that the network  is  currently
          unreachable.

     Neighbor #

          The neighbor gateway that is the next hop to reach this
          network.    This   is   an   index  into  the  previous
          information on this gateway's neighbor gateways.   This
          field  is  only  valid  if the Distance is greater than
          zero.

























                              -70-
