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IEN - 197 A Host Monitoring Protocol Benjamin M. Littauer Andrew J. Huang Robert M. Hinden Bolt Beranek and Newman Inc. September 1981 IEN-197 September 1981 Table of Contents 1 Introduction.......................................... 1 2 Protocol Operation.................................... 2 2.1 Unsolicited Messages................................ 3 2.2 Status Messages..................................... 4 2.3 Statistics Messages................................. 4 3 Header Formats........................................ 6 3.1 IP Headers.......................................... 6 3.2 Monitor Header...................................... 7 4 Monitor Message Formats............................... 9 4.1 System Type 1: General Messages..................... 9 4.1.1 Message Type 1: Polling Message................... 9 4.1.2 Message Type 2: Error in Poll.................... 11 4.2 System Type 2: IMP................................. 13 4.2.1 Message Type 1: IMP Trap......................... 13 4.2.2 Message Type 2: IMP status....................... 16 4.2.3 Message Type 3: IMP Modem Throughput............. 20 4.2.4 Message Type 4: IMP Host Throughput.............. 23 4.3 System Type 3: TAC................................. 26 4.3.1 Message Type 1: TAC Trap Message................. 26 4.3.2 Message Type 2: TAC Status....................... 29 4.3.3 Message Type 3: TAC Throughput................... 32 -i- IEN-197 September 1981 A Host Monitoring Protocol 1 Introduction The Host Monitoring Protocol (HMP) is used to collect information from hosts in various networks. At present the protocol aims at collecting information from ARPANET IMPs and TACs in an internet environment. It is designed to be extensible to other monitoring functions (e.g. hosts, gateways, local nets) while its addressing and control structures allow it to operate as well within a single network. In implementation it is a portion of a larger system, the Network Operations Center (NOC). The monitoring algorithm relies on polling for messages; the Host Monitor (HM) periodically sends a polling message to the host being monitored, requesting a specified report. The host then creates the report and sends it to the HM. Missing reports are detected as unanswered polls and duplicate polls are sent to have the report retransmitted. Some messages cannot be polled for and these are sent to the HM spontaneously. Checksums calculated on the data portions of all messages assure their integrity. The HMP implements a password scheme in order to restrict access to monitoring information. The monitored hosts check each -1- IEN-197 September 1981 poll message for a valid password before responding; this helps prevent unauthorized use of the monitor system. The HMP is not intended to be a highly secure protocol. 2 Protocol Operation The HMP is designed to operate reliably in the internet environment. To gain this measure of reliability it uses polling. The HM sends polling messages requesting reports to the monitored hosts. A host, upon receiving the poll, verifies the message and, if it is acceptable, sends the appropriate report to the poll source. The HM, after transmitting the poll, awaits the corresponding report. If it is not received within a reasonable interval, another poll is sent assuming that either the previous poll or the answering report was lost. If after a number of repeated polls no response has been received, it can be reasonably concluded that the host is unreachable and the polling frequency is reduced to a background level. This minimizes traffic but, since polling continues, a poll will reach the host once it becomes reachable. When a report is received the normal poll frequency is resumed. The most important reason for choosing polling over other methods of detecting lost messages is that it centralizes control -2- IEN-197 September 1981 of monitoring in a dedicated HM, rather distributing it throughout the network of monitored hosts. This frees resources in the monitored systems and also allows the HM to regulate the flow of monitoring messages to prevent overloading of the HM's resources. There are three classes of data with which the monitoring protocol is concerned. These are (1) reports of unexpected changes of status or error conditions, (2) reports of the current state of the host, and (3) reports of statistics and throughput data. These three kinds of data are handled in different ways by the HMP as described below. 2.1 Unsolicited Messages These are reports of unexpected changes of status or error condition reports (traps) which the monitor should be informed of as they occur. They are not polled, but are instead sent directly to a particular HM. If the address of the HM must be changed for unsolicited messages, it will be done by external means (e.g. packet core protocol). -3- IEN-197 September 1981 2.2 Status Messages These are reports of the current state of a system; they contain any kind of information which is not cumulative. The HM will poll for these on a periodic basis. When a monitored host receives a poll for a status message, it assembles a message with the current data pertaining to its status. Since this is an instantaneous "picture" of a system, it is not critical if any particular status report is lost. 2.3 Statistics Messages These messages, also called throughput messages, contain data collected on a periodic basis. The information will be collected in a monitored machine using a double buffering system. At the end of each collection period, a message will be assembled and the counters will be cleared. During the next collection period, any HMs polling for a statistics message will be sent this message. The collection frequency for statistics messages from a particular host must be relatively long compared to the average round trip message time between the HM and that host to allow the HM to re-poll if it does not receive an answer. With this restriction it should be possible to avoid missing any statistics messages in most cases. Each statistics message will contain a -4- IEN-197 September 1981 field giving the (local) time when the data was collected, and the time at which the message was sent (*). This will allow the HM to schedule its polling so that the poll arrives near the beginning of each collection period. This is done to ensure that if a message is lost, the HM will have sufficient time to try again to get the statistics message for that period. Sequence numbers will be used to detect the loss of a message for a period, and also to eliminate duplicate messages. _______________ * The units of the local time should be large enough to guarantee a rollover time of at least one hour. -5- IEN-197 September 1981 3 Header Formats [Note: Any field labeled "unused" is reserved for later extensions and must be zero when sent.] Monitor messages have the following format: +----------------+ | Local Network | | Header(s) | +----------------+ | IP header | +----------------+ | Internet | | Monitor | | Header | +----------------+ | D | | A | | T | | A | +----------------+ | Padding | +----------------+ The local header(s) depend on the local network, and do not concern us here. 3.1 IP Headers HMP messages are sent using the version 4 IP header as described in IEN-128 (RFC-760). The HMP protocol number is 20 (decimal). The time to live field should be set to the maximum value. All other fields should be set as specified in IEN-128. -6- IEN-197 September 1981 3.2 Monitor Header The monitor header format is: 1 0 0 0 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +---------------+---------------+ 0 | System Type | Message Type | +---------------+---------------+ 1 | Port Number | +---------------+---------------+ 2 | Sequence Number | +---------------+---------------+ 3 | Password or Returned Seq. # | +---------------+---------------+ 4 | One's Complement Checksum | +---------------+---------------+ HMP FIELDS: System Type Message Type The combination of system type and message type determines the format of the data in the monitoring message. The system types which have been defined are: System Type | Meaning ----------------+----------------- 1 | General Messages 2 | IMP 3 | TAC Message types are defined for each system type according to the needs of that system. Message types and their formats for each system are defined below. Port Number The Port Number field is presently unused. It can be used to multiplex similar messages from/to different processes in one host. Sequence Number Every message contains a sequence number. The sequence number is incremented when each new message of that type is sent. -7- IEN-197 September 1981 Password or Returned Sequence Number The Password field of a polling message from an HM contains a password to verify that the HM is allowed to gather information. Responses to polling messages copy the Sequence Number from the polling message and return it in this field for identification and round-trip time calculations. Checksum The Checksum field is the one's complement of the one's complement sum of all the 16-bit words in the header and data area. As with the checksum in the TCP header (see IEN-129), the checksum also covers a 96-bit pseudo header containing the source address, the destination address, the protocol (20), and the length of the monitoring message in bytes. The fields of the pseudo header are as defined for the IP header. -8- IEN-197 September 1981 4 Monitor Message Formats 4.1 System Type 1: General Messages 4.1.1 Message Type 1: Polling Message Description The HM will send polls to the machines it is monitoring according to its polling algorithm. Multiple requests can be combined in a single message, but each request is still considered a separate poll. The polled machine will return a message of each type requested; it will only answer a poll with the correct system type and password. It will return an error message (System Type 1; Message Type 2) if it receives a poll for the wrong system type or an unsupported message type. A polling message has the following form: 1 0 0 0 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +---------------+---------------+ 0 | R-Message Type| R-Subtype | . +---------------+---------------+ . : :\ additional . : : > message : :/ requests +---------------+---------------+ HMP FIELDS System Type General Messages = 1 Message Type Polling Message = 1 Port Number Unused Sequence Number The sequence number identifies the polling request. An HM will have separate sequences for each host it monitors. The sequence number is returned in the response to a poll; the -9- IEN-197 September 1981 HM will use this information to associate polls with their responses and to determine round trip times. Password The monitoring password. POLL FIELDS R-Message Type The message type requested. R-Subtype Presently unused, this field might later be used to specify options or include additional data in a polling message. -10- IEN-197 September 1981 4.1.2 Message Type 2: Error in Poll Description This message is sent in response to a faulty poll and specifies the nature of the error. An error message has the following form: 1 0 0 0 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +---------------+---------------+ 0 | Error Type |\ first +---------------+---------------+ > error 1 | R-Message Type| R-Subtype |/ report . +---------------+---------------+ . : :\ additional . : : > error : :/ reports +---------------+---------------+ HMP FIELDS System Type General Messages = 1 Message Type Error Message = 2 Port Number Unused Sequence Number A 16 bit number incremented each time an error message is sent. Returned Sequence Number The Sequence Number of the polling message which caused the error. -11- IEN-197 September 1981 ERROR MESSAGE FIELDS Error Type This field specifies the nature of the error in the poll. The following error types have been defined. 1 = Reason unspecified. 2 = Bad R-Message Type. 3 = Bad R-Subtype. R-Message Type R-Subtype These fields identify the poll request in error. -12- IEN-197 September 1981 4.2 System Type 2: IMP 4.2.1 Message Type 1: IMP Trap Description When a trap occurs, it is buffered in the IMP and sent as soon as possible. Trap messages are unsolicited. If traps happen in close sequence, several traps may be sent in one message. Through the use of sequence numbers, it will be possible to determine how many traps are being lost. If it is discovered that many are lost, a polling scheme might be implemented for traps. A IMP trap message has the following form: 1 0 0 0 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +---------------+---------------+ 0 | # of traps lost | +---------------+---------------+ 1 : first : . : trap : . : data : . +---------------+---------------+ . : additional : . : trap : . : data : +---------------+---------------+ HMP Fields System Type IMP = 2 Message Type IMP Trap Message = 1 Port Number Unused Password Unused -13- IEN-197 September 1981 Sequence Number A 16 bit number incremented each time a trap message is sent so that the HM can order the received trap messages and detect missed messages. IMP TRAP FIELDS # of traps lost Under certain conditions, an IMP may overflow its internal trap buffers and be unable to save traps to send. This counter keeps track of such occurrences. Trap Reports There can be several blocks of trap data in each message. The format for each such block is below. +---------------+---------------+ | Size | +---------------+---------------+ | Time | +---------------+---------------+ | Trap ID | +---------------+---------------+ : Trap : : Data : +---------------+---------------+ Size Size is the number of 16 bit words in the trap, not counting the size field. Time The time (in 640 ms. units) at which the trap occurred. This field is used to sequence the traps in a message and associate groups of traps. Trap ID This is usually the program counter at the trap. The ID identifies the trap, and does not have to be a program counter, provided it uniquely identifies the trap. -14- IEN-197 September 1981 Trap Data The IMP returns data giving more information about the trap. There are usually two entries: the values in the accumulator and the index register at the occurrence of the trap. -15- IEN-197 September 1981 4.2.2 Message Type 2: IMP status Description The status message gives a quick summary of the state of the IMP. Status of the most important features of the IMP are reported as well as the current configuration of the machine. The format of the status message is as follows: 1 0 0 0 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +---------------+---------------+ 0 | Software Version Number | +---------------+---------------+ | Last Trap Message | +---------------+---------------+ | Hosts | Modems | +---------------+---------------+ | Package bits | +---------------+---------------+ | TIP version | +---------------+---------------+ 5 | restart/reload | +---------------+---------------+ | Host | + + | Test | + + | Results | +---------------+---------------+ | | + Crash + 10 | | + Data + | | +---------------+---------------+ | Anomalies | +---------------+---------------+ 13 | HIHD0 | HIHD1 | HIHD2 | HIHD3 | . +---------------+---------------+ . : HIHD4 | ............... : . +---------------+---------------+ (cont.) -16- IEN-197 September 1981 Imp Status (cont.) . +---------------+---------------+ . | Modem | . + State + . | Data | . +---------------+---------------+ . : Modem State : . : Data...... : +---------------+---------------+ HMP FIELDS System Type IMP = 2 Message Type IMP status message = 2 Port Number Unused Sequence Number A 16 bit number incremented each time a status message is sent. Password The password contains the sequence number of the polling message to which this message responds. IMP STATUS FIELDS Software Version Number The IMP version number. Last Trap Message Contains the sequence number of the last trap message sent to the HM. This will allow the HM to detect how many trap messages are being lost. -17- IEN-197 September 1981 Hosts The number of configured hosts in this system. Modems The number of configured modems in this system. Package Bits This is a bit encoded word that reports the set of packages currently loaded in the system. The table below defines the bits. Bit Package (octal) 1 VDH 2 TIP 4 experimental 10 Cumulative Statistics 20 Trace 40 TTY 100 DDT 200 Store and Forward statistics 400 End-to-end Statistics 1000 Level measurements TIP version The TIP version number if a TIP is loaded or zero if not. Restart/Reload This word reports a restart or reload of an IMP. Value Meaning 1 restarted 2 reloaded Host Test Results These three words report the result of the host test, if any. If a test is running, the first word will contain the host number, the second and third will contain the number of NOPs sent and received, respectively. If no test is running, the first word will contain a -1. Crash Data Crash data reports the circumstances surrounding an -18- IEN-197 September 1981 unexpected crash. The first word reports the location of the crash and the following two are the contents of the accumulator and index registers. Anomalies Anomalies is a collection of bit flags that indicate the state of various switches or processes in the IMP. These are very machine dependent and only a representative sampling of bits is listed below. Bit Meaning (octal) 1 Sense Switch 1 ON 2 Sense Switch 2 ON 4 Sense Switch 3 ON 10 Sense Switch 4 ON 20 Override ON 200 Trace ON 2000 Message Generator ON HIHD0 - HIHDn Each four bit HIHD field gives the state of the corresponding host. Value Meaning 0 UP 1 ready line down 2 tardy 3 non-existent 4 VDH host not initialized Modem State Data Modem state data contains four byte fields of data. The first field indicates the line speed in a machine dependent fashion; the second field is the number of line protocol ticks covered by this report; the third is the neighbor on the line, and the fourth is a count of missed protocol packets over the interval specified in the second field. -19- IEN-197 September 1981 4.2.3 Message Type 3: IMP Modem Throughput Description The modem throughput message reports traffic statistics for each modem in the system. The IMP will collect these data at regular intervals and save them awaiting a poll from the HM. If a period is missed by the HM, the new results simply overwrite the old. Two time stamps bracket the collection interval (data-time and prev-time) and are an indicator of missed reports. In addition, mess-time indicates the time at which the message was sent. The modem throughput message will accommodate up to fourteen modems in one packet. A provision is made to split this into multiple packets by including a modem number for the first entry in the packet. This field is not immediately useful, but if machine sizes grow beyond fourteen modems or if modem statistics become more detailed and use more than three words per modem, this can be used to keep the message within a single ARPANET packet. The format of the modem throughput message is as follows: 1 0 0 0 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +---------------+---------------+ 0 | Mess-Time | +---------------+---------------+ | Software Version Number | +---------------+---------------+ | Data-Time | +---------------+---------------+ | Prev-Time | +---------------+---------------+ | Total Modems | This Modem | +---------------+---------------+ 5 | | . + modem + . | | . + throughput + . | | . +---------------+---------------+ . : modem : . : : . : throughput : +---------------+---------------+ -20- IEN-197 September 1981 HMP FIELDS System Type IMP = 2 Message Type IMP Modem Throughput message = 3 Port Number Unused Sequence Number A 16 bit number incremented at each collection interval (i.e. when a new throughput message is assembled). The HM will be able to detect lost or duplicate messages by checking the sequence numbers. Password The password contains the sequence number of the polling message to which this message responds. IMP MODEM THROUGHPUT FIELDS Mess-time The time (in 640ms. units) at which the message was sent to the HM. Software Version Number The IMP version number. Data-Time Data-time is the time (in 640ms. units) when this set of data was collected. (See Description.) Prev-Time Prev-time is the time (in 640 ms. units) of the previous collection of data (and therefore, is the time when the data in this message began accumulating.) Total Modems -21- IEN-197 September 1981 This is the number of modems in the system. This Modem This Modem is the number of the first modem reported in this message. Large systems that are unable to fit all their modem reports into a single packet may use this field to separate their message into smaller chunks to take advantage of single packet message efficiencies. Modem Throughput Modem throughput consists of three words of data reporting packets and words output on each modem. The first word counts packets output and the following two count word throughput. The double precision words are arranged high order first. (Note also that messages from Honeywell type machines (316s, 516s and C30s) use a fifteen bit low order word.) The first block reports output on the modem specified by "This Modem". The following blocks report on consecutive modems. -22- IEN-197 September 1981 4.2.4 Message Type 4: IMP Host Throughput Description The host throughput message reports traffic statistics for each host in the system. The IMP will collect these data at regular intervals and save them awaiting a poll from the HM. If a period is missed by the HM, the new results simply overwrite the old. Two time stamps bracket the collection interval (data-time and prev-time) and are an indicator of missed reports. In addition, mess-time indicates the time at which the message was sent. The host throughput format will hold only three hosts if packet boundaries are to be respected. A provision is made to split this into multiple packets by including a host number for the first entry in the packet. The format of the host throughput message is as follows: 1 0 0 0 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +---------------+---------------+ 0 | Mess-Time | +---------------+---------------+ | Software Version Number | +---------------+---------------+ | Data-Time | +---------------+---------------+ | Prev-Time | +---------------+---------------+ | Total Hosts | This Host | +---------------+---------------+ 5 : host : . : throughput : +---------------+---------------+ HMP FIELDS System Type IMP = 2 Message Type IMP host Throughput message = 4 Port Number Unused -23- IEN-197 September 1981 Sequence Number A 16 bit number incremented at each collection interval (i.e. when a new throughput message is assembled). The HM will be able to detect lost or duplicate messages by checking the sequence numbers. Password The password contains the sequence number of the polling message to which this message responds. IMP HOST THROUGHPUT FIELDS Mess-time The time (in 640ms. units) at which the message was sent to the HM. Software Version Number The IMP version number. Data-Time Data-time is the time (in 640ms. units) when this set of data was collected. (See Description.) Prev-Time Prev-time is the time (in 640 ms. units) of the previous collection of data (and therefore, is the time when the data in this message began accumulating.) Total Hosts The total number of hosts in this system. This Host This host is the number of the first host reported in this message. Large systems that are unable to fit all their host reports into a single packet may use this field to separate their message into smaller chunks to take advantage of single packet message efficiencies. -24- IEN-197 September 1981 Host Throughput Each host throughput block consists of twelve words in the following format: +---------------+---------------+ | messages to network | +---------------+---------------+ | messages from network | +---------------+---------------+ | packets to net | +---------------+---------------+ | packets from net | +---------------+---------------+ | messages to local | +---------------+---------------+ | messages from local | +---------------+---------------+ | packets to local | +---------------+---------------+ | packets from local | +---------------+---------------+ | words to imp | | (double precision) | +---------------+---------------+ | words from imp | | (double precision) | +---------------+---------------+ Each host throughput message will contain several blocks of data. The first block will contain data for the host specified in First Host Number. Following blocks will contain data for consecutive hosts. All counters are single precision with the exception of the two word counters which are double precision. The double precision words are arranged high order first. Note also that messages from Honeywell type machines (316s, 516s and C30s) use a fifteen bit low order word. -25- IEN-197 September 1981 4.3 System Type 3: TAC 4.3.1 Message Type 1: TAC Trap Message Description When a trap occurs, it is buffered in the TAC and sent as soon as possible. Trap messages are unsolicited. If traps happen in close sequence, several traps may be sent in one message. Through the use of sequence numbers, it will be possible to determine how many traps are being lost. If it is discovered that many are lost, a polling scheme might be implemented for traps. A TAC trap message has the following form: 1 0 0 0 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +---------------+---------------+ 0 | # of traps lost | +---------------+---------------+ 1 : first : . : trap : . : data : . +---------------+---------------+ . : additional : . : trap : . : data : +---------------+---------------+ HMP FIELDS System Type TAC = 3 Message Type TAC Trap Message = 1 Port Number Unused Password or Returned Sequence Number Unused -26- IEN-197 September 1981 Sequence Number A 16 bit number incremented each time a trap message is sent so that the HM can order the received trap messages and detect missed messages. TAC TRAP FIELDS # of traps lost Under certain conditions, a TAC may overflow its internal trap buffers and be unable to save traps to send. This counter keeps track of such occurrences. Trap Reports There can be several blocks of trap data in each message. The format of the trap data is as follows: +---------------+---------------+ | Size | +---------------+---------------+ | Time | +---------------+---------------+ | Trap ID | +---------------+---------------+ : Trap : : Data : +---------------+---------------+ Size Size is the number of 16 bit words in the trap, not counting the size field. Time The time (in 640ms. units) at which the trap occurred. This field is used to sequence the traps in a message and associate groups of traps. Trap ID This is (usually) the program counter at the trap. The ID identifies the trap, and does not have to be a program counter, provided that it uniquely identifies the trap. -27- IEN-197 September 1981 Trap Data The TAC returns data giving more information about the trap. There are usually two entries: the values in the accumulator and the index register at the occurrence of the trap. -28- IEN-197 September 1981 4.3.2 Message Type 2: TAC Status Description The status message gives a quick summary of the state of the TAC. Status of the most important features of the TAC are reported as well as the current configuration of the machine. A TAC status message has the following form: 1 0 0 0 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +---------------+---------------+ 0 | Version Number | +---------------+---------------+ | Last Trap Message | +---------------+---------------+ | Bit Flags | +---------------+---------------+ | Free PDB count | +---------------+---------------+ | Free MBLK count | +---------------+---------------+ 5 | # of TCP connections | +---------------+---------------+ | # of NCP connections | +---------------+---------------+ | restart/reload | +---------------+---------------+ | | + Crash + | | + Data + 10 | | +---------------+---------------+ HMP FIELDS System Type TAC = 3 Message Type TAC Status Message = 2 -29- IEN-197 September 1981 Port Number Unused Sequence Number A 16 bit number incremented each time a status message is sent. Returned Sequence Number Contains the sequence number from the polling message requesting this report. TAC STATUS FIELDS Version Number The TAC's software version number. Last Trap Message Contains the sequence number of the last trap message sent to the HM. This will allow the HM to detect how many trap messages are being lost. Bit Flags There are sixteen bit flags available for reporting the state of various switches (hardware and software) in the TAC. The bits are numbered as follows for purposes of the discussion below. 1 1 0 0 0 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | | | | | | | | | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The bit flags report the status of the following: Bit Meaning 0 0 => DDT override off; 1 => override on. 1-4 0 => Sense Switch n is off; 1 => SSn on. 5 0 => Extended DDT not enabled; 1 => Extended DDT enabled. 6 0 => Traps going to console; 1 => Traps going to remote monitor. 7-15 unused -30- IEN-197 September 1981 Free PDB count The number of PDBs on the free queue. Free MBLK count The number of MBLKs on the free queue. # of TCP connections # of NCP connections The number of open connections for each protocol. Restart/Reload This word reports a restart or reload of the TAC Value Meaning 1 restarted 2 reloaded Crash Data Crash data reports the circumstances surrounding an unexpected crash. The first word reports the location of the crash and the following two are the contents of the accumulator and index registers. -31- IEN-197 September 1981 4.3.3 Message Type 3: TAC Throughput Description The TAC throughput message reports statistics for the various modules of the TAC. The TAC will collect these data at regular intervals and save them awaiting a poll from the HM. If a period is missed by the HM, the new results simply overwrite the old. Two time stamps bracket the collection interval (data-time and prev-time) and are an indicator of missed reports. In addition, mess-time indicates the time at which the message was sent. A TAC throughput message has the following form: 1 0 0 0 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +---------------+---------------+ 0 | Mess-Time | +---------------+---------------+ | Data-Time | +---------------+---------------+ | Prev-Time | +---------------+---------------+ | Version Number | +---------------+---------------+ | Last Trap Message | +---------------+---------------+ 5 | Bit Flags | +---------------+---------------+ | Free PDB count | +---------------+---------------+ | Free MBLK count | +---------------+---------------+ | # of TCP connections | +---------------+---------------+ | # of NCP connections | +---------------+---------------+ ---- 10 | Host Input Throughput | ^ +---------------+---------------+ | | Host Input Abort Count | | +---------------+---------------+ | | Host Input Garbled Count | | +---------------+---------------+ | | Host Output Throughput | 1822 info. +---------------+---------------+ | (continued) -32- IEN-197 September 1981 TAC throughput (cont.) +---------------+---------------+ | | Host Output Abort Count | 1822 info. +---------------+---------------+ | 15 | Host Down Count | v +---------------+---------------+ ---- | # of datagrams sent | ^ +---------------+---------------+ | | # of datagrams received | | +---------------+---------------+ IP info. | # of datagrams discarded | | +---------------+---------------+ | | # of fragments received | v +---------------+---------------+ ---- 20 | # of segments sent | ^ +---------------+---------------+ | | # of segments received | | +---------------+---------------+ | | # of segments discarded | | +---------------+---------------+ TCP info. | # of octets sent | | +---------------+---------------+ | | # of octets received | | +---------------+---------------+ | 25 | # of retransmissions | v +---------------+---------------+ ---- | # of messages sent | ^ +---------------+---------------+ | | # of messages received | | +---------------+---------------+ | | # of messages flushed | | +---------------+---------------+ | | # of bytes sent | | +---------------+---------------+ | 30 | # of bytes received | | +---------------+---------------+ NCP info. | # of ERRs received | | +---------------+---------------+ | | # of RASs received | | +---------------+---------------+ | | # of RAPs received | | +---------------+---------------+ | | # of NXSs received | | +---------------+---------------+ | 35 | # of NXRs received | | +---------------+---------------+ | | # of RSTs received | v +---------------+---------------+ ---- -33- IEN-197 September 1981 HMP FIELDS System Type TAC = 3 Message Type TAC Throughput Message = 3 Port Number Unused Sequence Number A 16 bit number incremented at each collection interval (i.e. when a new throughput message is assembled). The HM will be able to detect lost or duplicate messages by checking the sequence numbers. Returned Sequence Number Contains the sequence number from the polling message requesting this report. TAC THROUGHPUT FIELDS Mess-time The time (in 640ms. units) at which the message was sent to the HM. Data-Time Data-time is the time (in 640ms. units) when this set of data was collected. (See Description.) Prev-Time Prev-time is the time (in 640 ms. units) of the previous collection of data (and therefore, is the time when the data in this message began accumulating.) Version Number The TAC's software version number. -34- IEN-197 September 1981 Last Trap Message Contains the sequence number of the last trap message sent to the HM. This will allow the HM to detect how many trap messages are being lost. Bit Flags There are sixteen bit flags available for reporting the state of various switches (hardware and software) in the TAC. The bits are numbered as follows for purposes of the discussion below. 1 1 0 0 0 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | | | | | | | | | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The bit flags report the status of the following: Bit Meaning 0 0 => DDT override off; 1 => override on. 1-4 0 => Sense Switch n is off; 1 => SSn on. 5 0 => Extended DDT not enabled; 1 => Extended DDT enabled. 6 0 => Traps going to console; 1 => Traps going to remote monitor. 7-15 unused Free PDB count The number of PDBs on the free queue. Free MBLK count The number of MBLKs on the free queue. # of TCP connections # of NCP connections The number of open connections for each protocol. -35- IEN-197 September 1981 1822 info. These six fields report statistics which concern the operation of the 1822 protocol module, i.e. the interface between the TAC and its IMP. IP info. These four fields report statistics which concern Internet Protocol in the TAC. TCP info. These six fields report statistics which concern TCP protocol in the TAC. NCP info. These eleven fields report statistics which concern NCP protocol in the TAC. -36-