United States Patent [191
`Bauer et al.
`
`US005367635A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,367,635
`Nov. 22, 1994
`
`[54] NETWORK MANAGENIENT AGENT WITH
`USER CREATED OBJECTS PROVIDING
`ADDITIONAL FUNCTIONALITY
`[75] Inventors: Neal Bauer, Loveland; Mark A.
`Kepke, Ft. Collins, both of C010.
`[73] Assignee: Hewlett-Packard Company, Palo
`Alto, Calif.
`[21] Appl. No.5 752,152
`[22] Filed:
`Aug. 29, 1991
`
`[51] Int. Cl.5 . . . . . .
`
`. . . . . . . . . . . . . .. G06F 13/00
`
`[52] US. Cl. .................................. .. 395/200; 395/425;
`395/600; 395/650; 395/700; 395/775;
`364/DIG. 1; 364/221; 364/222.81; 364/222.82;
`364/280; 364/280.2; 364/280.3; 364/284
`[58] Field of Search ................... .. 395/600; 364/280.9,
`364/280.3, 280.2
`
`[56]
`
`References Cited
`PUBLICATIONS
`Individuals connected with Columbia University; “Ker
`mit”; Screen prints of computer program.
`Novell, Inc.; Net Wave Version 3.1] System Administra
`tion, Novell, Inc., 1991.
`Simrin; The MS-DOS Bible; Howard Sams 8: 00.; pp.
`389-390.
`IEEE Communications Magazine, vol. 29, No. 7, Jul.
`
`. .
`
`1991, pp. 29-38, N. Modiri “An Implementation .
`Information Service Element Interfaces”.
`The Simple Book: An Introduction to Management of
`TCP/IP-Based Internets, 1991, pp. 69-244, Marshall T.
`Rose.
`IRE WESCON Convention Record, vol. 35, Nov.
`1991, pp. 190-195, S. R. Reasoner, “Management by
`Proxy Agen ”.
`Primary Examiner—Thomas M. Heckler
`Assistant Examiner-J. Hall Backenstose
`Attorney, Agent, or Firm-Augustus W. Win?eld
`[57]
`ABSTRACT
`A computer network management software agent
`which includes the ability for users to add new user
`de?ned management objects. A user editable text ?le
`de?nes object identi?cations, object types, and the path
`and name of associated executable software. A user’ can
`then invoke user de?ned executable software at a man
`aged node by sending a network command and a user
`de?ned associated object identi?er to the agent in the
`managed node. Data can be sent between a user and
`user de?ned executable software. A timeout feature
`generates an error if commands are not completed
`within a user de?ned time.
`
`1 Claim, 6 Drawing Sheets
`
`STANDARD OBJECTS
`
`AGENT
`502
`
`\ (204
`VENDOR
`DEFINED
`OBJECTS
`
`/ Z08
`
`C(NFIGURAWN FILE
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`1
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`Nov. 22, 1994
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`
`U.S. Patent
`
`Nov. 22, 1994
`
`Sheet 6 of 6
`
`5,367,635
`
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`

`
`1
`
`NETWORK MANAGEMENT AGENT WITH USER
`CREATED OBJECTS PROVIDING ADDITIONAL
`FUNCTIONALITY
`
`FIELD OF INVENTION
`This invention relates generally to computer net
`works, and more particularly to network management
`software.
`
`BACKGROUND OF THE INVENTION
`Computers may be interconnected via a local area
`network (LAN). Local area networks may be intercon
`nected into still larger systems spanning a floor or build
`ing, a group of buildings (campus), a region, or larger
`areas on up to worldwide systems. Each LAN may
`have a different hardware interconnection technology
`and multiple network protocols. A simple isolated LAN
`may be administered by individual users. That is, users
`may change equipment, install software, and diagnose
`problems. Large complex LANs or large groups of
`interconnected LANs require “management”. “Man
`agemen ” refers to both a human network manager and
`software used by the human manager. In this applica
`tion, “management” refers to software for managing the
`overall system, and “user” refers to a person using the
`network management software. The user is usually the
`system administrator. Users can obtain management
`data and alter management data on the network by
`using network management software.
`30
`Large network systems are typically dynamic with
`continual requirements for addition and deletion of
`equipment, updating of software, and detection and
`analysis of problems. In general, there may be a variety
`of systems from a variety of vendors with a variety of
`35
`system owners. Management software is designed to be
`as general as possible. However, as the overall system
`changes, the user may need information or control ca
`pabilities not anticipated by the designers of the man
`agement software. Management software needs to have
`a provision for adding new user de?ned capabilities for
`information gathering and control.
`Current network management software is typically
`de?ned in terms of software objects. A software object
`is a way of organizing data. An object may have a value
`or associated data. An object may have an associated
`executable software process for generating data or for
`control purposes. A user can retrieve or alter the data
`associated with an object. Network management ob
`jects are uniquely identi?ed by object identi?ers.
`An agent is software running as a background process
`on each of the target devices. When a user requests
`management data from a device on the network, man
`agement software will send an object identi?cation in a
`management packet or frame to the target agent. The
`55
`agent will interpret the object identi?cation, retrieve
`data associated with the object identi?cation, and send
`the data in a packet back to the user. Sometimes, a
`corresponding process may be invoked to retrieve data.
`Current network management agent software is typi
`cally sold with a hierarchy of ?xed pre-de?ned objects.
`There are typically no provisions for a user to add or
`modify objects. Some management software provides
`“extensible” agents. “Extensible” typically means that a
`user has access to source code for the agent and can
`65
`modify the source code and recompile. Alternatively,
`the user may write additional code in a programming
`language which requires compilation but may not be
`
`10
`
`45
`
`5,367,635
`2
`required to recompile the original agent. In either case,
`writing source code in a programming language and
`compilation of the source code is required. There is a
`need for users to have the capability to add objects and
`associated processes without having to write code in a
`programming language requiring compilation.
`There are numerous standards organizations which
`are attempting to standardize computer’ networking.
`The International Organization for Standardization
`(ISO) has provided a general reference framework
`called the Open System Interconnection (081) model.
`The 051 model for a network management protocol is
`called Common Management Information Protocol
`(CMIP). CMIP is a common network management
`protocol in Europe. In the United States, a more com
`mon network management protocol is a related varia
`tion of CMIP called the Simple Network Management
`Protocol (SNMP) (see Marshall T. Rose, The Simple
`Book, Prentice-Hall, 1991).
`In the SNMP network management terminology, a
`network management system contains at least one net
`work management station (NMS), several managed
`nodes, each containing an agent, and a network man
`agement protocol which is used by the management
`station and the agents to exchange management infor
`mation. A user can obtain data and alter data on the
`network by using network management software on the
`NMS to communicate with agent software in the man
`aged nodes.
`Software for agents conforming to SNMP standards
`is commercially available. Agent source code is also
`available without charge from universities. For exam
`ple, a source code SNMP development kit (hereinafter
`referred to as the “MIT code”) is available from the
`following source:
`James R. Davin
`Advanced Network Architecture Group
`M.I.T. Laboratory for Computer Science
`545 Technology Square
`Cambridge, Mass. 02139
`The SNMP de?nes a structure for a management
`database (a collection of objects) called the Manage
`ment Information Base (MIB). Objects in a MIB have
`names (OBJECT IDENTIFIERS) and data structures
`(OBJECT TYPES). An object identi?er is a sequence
`of non-negative integer values which signify a path
`through a tree structure of numbered branches (called
`sub-identi?ers). Each sub-identi?er is a non-negative
`integer.
`For example,
`the
`object
`identi?er
`l.3.6.l.4.1.1l.2.12 identi?es an object found by starting
`at the root, moving to the branch with the sub-identi?er
`1, moving to a subordinate branch with the sub-iden
`ti?er 3, and so forth. The ?rst 6 levels of this example
`are de?ned by the standard model. In the example, the
`branch identi?ed by the ?rst ?ve sub-identi?ers
`(1.3.6.1.4) is the standard SNMP de?ned branch called
`“private”. The next sub-identi?er (1) is for a branch
`(called “enterprises”) reserved for vendor speci?c ob
`6o jects. The next label (11) is reserved for Hewlett Pack
`ard.
`Information is retrieved from an agent by sending a
`SNMP GET or GET-NEXT request with an object
`identi?cation as a parameter. Data associated with an
`object can be altered by sending a SNMP SET request
`to the agent with the object identi?cation as one param
`eter and the data as another parameter. An object which
`can be written to is called a “settable” object.
`
`50
`
`8
`
`

`
`5,367,635
`3
`4
`The MIT code includes a function (named “misEx
`FIG. 2 is a software block diagram illustrating addi
`port()”) for registering (attaching or grafting) an object
`tional detail within an agent.
`FIGS. 3A and 3B illustrate an example agent con?gu
`to the object tree structure. There are 4 parameters as
`follows:
`ration file in accordance with the present invention.
`name: (the object identi?er)
`FIGS. 4A and 4B illustrate pseudocode for reading a
`namelen: (the number of sub-identi?ers in the object
`con?guration ?le and registering user de?ned objects
`identi?er)
`with a vendor de?ned object tree structure.
`ops: (a list of 6 routines (corresponding to the opera
`tions RELEASE, CREATE, DESTROY, and
`SNMP requests GET-NEXT, GET, and SET)
`which can be performed on management objects)
`cookie: (a pointer to stored parameters associated
`with the speci?c object identi?er within a data
`structure internal to the agent).
`MIB standards evolve as required by the industry.
`Proposed MIB standards start as published requests for
`comments. A MIB format for de?ning objects is speci
`?ed in Request For Comments number 1212 (hereinaf
`ter referred to as “RFC 1212”) and an example MIB
`standard using that format is speci?ed in Request For
`20
`Comments 1213 (hereinafter referred to as “RFC
`1213”). Both are available from the following source:
`DDN Network Information Center
`SRI International
`Room EJ291
`333 Ravenswood Avenue
`Menlo Park, Calif. 94025
`The RFC 1212 object-type notation requires a series
`of textual clauses as follows:
`SYNTAX: (examples are
`“OCTET STRING”)
`ACCESS: (choices are: “read-only”, “read-write”,
`“write-only”, and “not-accessible”)
`STATUS: (the required choice for status in a com
`mercial product is “mandatory”. In an experimen
`tal MIB, the word “optional” is allowed.)
`DESCRIPTION: (A textual explanation of the ob
`ject delimited by quote marks.)
`As discussed above, there is a need in network man
`agement for users to have the capability of adding man
`agement objects to an agent without requiring recompi
`lation. However, the capability must be compatible
`with various standards as described above.
`
`25
`
`“INTEGER” and
`
`30
`
`35
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT OF THE
`INVENTION
`FIG. 1 illustrates a computer network 100. Network
`management station 102 manages a variety of managed
`nodes 104, 108. Each managed node has an agent 106,
`110 running as background software providing manage
`ment information and control. Each agent 106, 110 is
`con?gured as a tree structure of software objects.
`FIG. 2 illustrates additional detail within an agent.
`Agent 200 has a layer of standard objects 202 de?ned by
`RFC 1213, and a layer of vendor de?ned objects 204.
`Standard objects 202 and vendor de?ned objects 204
`are compiled and supplied by the network management
`software vendor. The present invention comprises soft
`ware within an agent 200 enabling the addition of user
`de?ned objects 206 to a previously compiled network
`management agent 200. User de?ned objects are de?ned
`in con?guration file 208. Agent 200 can be invoked to
`re-read con?guration ?le 208 and add user de?ned ob
`jects 206 to agent 200.
`The preferred embodiment of the present invention is
`an agent conforming to the SNMP model. Much of the
`following structure and nomenclature is common to
`other standards but is presented here speci?cally in
`terms of the SNMP. The preferred embodiment of the
`present invention uses the MIT code for the basic core
`of the agent software.
`The new agent in the present invention includes the
`capability of reading object de?nitions from a special
`?le called a con?guration ?le (208 in FIG. 2). The con
`?guration ?le (208) is a text ?le which can be edited by
`a user using any text editor. The con?guration ?le (208)
`can be de?ned at the time the new agent is installed or
`maybe de?ned later. The con?guration ?le (208) has a
`prede?ned UNIX path.
`The con?guration tile is compatible with the RFC
`1212 MIB standard described earlier. However, in the
`preferred embodiment, additional capability is incorpo
`rated into the textual DESCRIPTION clause. Four
`additional clauses are de?ned as follows:
`READ-COMMAND: (a path and name for an exe
`cutable program.)
`WRITE-COMMAND: (a path and name for an exe
`cutable program.)
`READ-COMMAND-TIMEOUT: (an integer speci
`fying a time in seconds allowed for completion of a
`READ-COMMAND.)
`WRITE-COMMAND-TIMEOUT: (an integer spec
`ifying a time in seconds allowed for completion of
`a WRITE-COMMAND).
`FIGS. 3A and 3B illustrate a sample con?guration
`?le. The object identi?er preamble (302) de?nes a MIB
`tree structure branch common to all user de?ned ob
`jects. In the sample illustrated in FIGS. 3A and 3B, the
`common branch is l.3.6.l.4.l.58. Then, for each de?ned
`object, the list de?nes a leaf which can be combined
`with the common branch to de?ne each object’s SNMP
`name (object identi?er). For example, an object labeled
`“pn'nterstatus” (304) de?nes a leaf (306) which appends
`
`40
`
`4-5
`
`50
`
`SUMMARY OF THE INVENTION
`The present invention provides a network manage
`ment agent having the capability of adding new objects
`to the agent without requiring modi?cation of the agent
`source code and without stopping and restarting the
`agent. These new objects can then be used by network
`management users to initiate user de?ned processes.
`In the present invention, user de?ned objects are
`de?ned in a con?guration ?le which is read by a net
`work management agent. The con?guration ?le is an
`editable text ?le which can be created at any time. The
`55
`agent can be invoked to re-read the con?guration ?le
`and incorporate objects in the con?guration ?le. Then,
`if a request for a user de?ned object reaches an agent,
`the appropriate user de?ned process is initiated to ac
`quire data, control a peripheral, or execute whatever is
`requested. Data is returned from the user de?ned pro
`cess back through the agent to the user. A timeout
`feature generates an error if commands are not com
`pleted within a user de?ned time.
`
`60
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a block diagram illustrating a computer
`network.
`
`65
`
`9
`
`

`
`30
`
`5
`the sub-identi?er 1 to a branch labeled “xyzprinter”
`which in turn_is_assigned the integer 1 in the preamble
`(302). The complete object identi?er for the user de
`?ned object
`labeled
`“printerstatus”
`is
`then
`1.3.6.l.4.1.58.l.l.0. The object labeled “printerstatus”
`(304) could be used to turn a printer on and off and to
`test the status of the printer. A request to read the
`printer status is initiated by a SNMP GET or GET
`NEXT request to the agent along with the object identi
`?er. The agent invokes a user speci?ed program desig
`nated in the read-command clause (308). The read-com
`mand clause (308) speci?es a UNIX path/usr/local/bin
`/and an executable program named “printer_status”.
`The read-command-timeout clause (310) speci?es that
`the agent will only wait 10 seconds for the printer__
`status command to respond. If the command takes
`longer than 10 seconds, an error message is returned to
`the management station. The syntax clause (312) speci
`?es that if the printer is on line (up), the object labeled
`“printerstatus” returns the integer 1 to the management
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`station. If the printer is off line (down), a 2 is returned.
`Likewise, a command to force the printer off line is
`accomplished by sending an integer argument 2 (down)
`to the user de?ned object “printerstatus” which in turn
`passes the argument and invokes a program named
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`“change._printer_.status” as de?ned in the write-com
`mand clause (314).
`FIG. 3B also illustrates a read-only object labeled
`“printertype” (316) to return a description string identi
`fying a printer type. Also illustrated in FIG. 3B is a
`read-only object labeled “user-logins” (318) to return a
`string containing identi?cations of all users currently
`logged onto the network. Continuing in FIG. 3B, the
`last example is a read-only object labeled “numusers”
`which returns the number of users logged onto the
`network.
`FIGS. 4A and 4B illustrate in comments and pseudo
`code the code which enables an agent to read the ob
`jects described in the con?guration ?le, to parse the
`special clauses within the description clause, to associ
`ate user speci?ed executable software with a user de
`?ned object identi?er, and to graft the user de?ned
`object to the primary tree structure that is de?ned by
`the vendor when the agent code is compiled. The
`misExport function described in the background section
`45
`is called to graft the user de?ned object to the primary
`tree structure. The misExport function is executed once
`for each user de?ned object.
`In FIGS. 4A and 4B, the human readable con?gura
`tion ?le is read (402) and information associated with
`each object is then saved in a separate internal data
`structure named “saved_values” (404). Then the
`misExport function is called to register the object (406).
`The ops parameter for the misExport function requires
`procedure names for responding to the SNMP GET,
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`GET-NEXT, and SET requests. In FIG. 4B, these are
`labeled “get_routine” (408), “getNext_routine” (410),
`and “set_routine” (412) respectively.
`Get-routine (408) is called when a SNMP GetRe
`quest is received by the agent for one of the objects
`registered from the con?guration ?le. Get_routine
`(408) uses the misExport cookie parameter (414) as a
`pointer into an internal data structure to identify the
`path and name of a UNIX shell command. The UNIX
`shell command will execute read-routine and read_
`65
`timeout (402) as speci?ed in the original con?guration
`?le. The getNext_.routine (412) and the set-routine
`(412) also use the cookie parameter (414) to point to a
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`UNIX shell command which executes user speci?ed
`procedures.
`Once an object is de?ned for an agent, a user at the
`network management station can then request data from
`that agent (e.g., an integer or a string) or initiate a pro
`cess within that agent (settable object). The user in
`vokes the user-def'med object by sending an SNMP
`request with an object identi?er and appropriate data
`arguments to the agent containing the object.
`At start-up, an agent searches for and reads the con
`?guration ?le. Once the con?guration ?le is read, the
`information is incorporated into the agent’s memory
`and the actual ?le is no longer needed. Therefore, the
`?le can be modi?ed while the agent is running. Also, the
`?le can be incorporated without requiring recompila
`tion of the agent. After start-up, the agent can be recon
`?gured (forced to re-read all con?guration ?les) by
`issuing an SNMP SetRequest to an object having the
`object identi?er 1.3.6.141.11.2.13.2.2.0 and setting the
`value to 1. This vendor-speci?c settable object exists in
`previous Hewlett Packard UNDI versions of SNMP
`compatible agents. The recon?gure object ?rst unregis
`ters all user de?ned objects previously registered. Then
`the process of reading the con?guration ?le and regis
`tration proceeds as described in FIGS. 4A and 4B.
`From the preceding discussion, it can be seen that the
`present invention provides a network management
`agent to which a user can add new management objects.
`The new user de?ned objects can be added without
`requiring recompilation of the agent and can be added
`without stopping the agent. This capability permits the
`user to expand the agent’s capability into areas not pro
`vided by the vendor for the agent. The agent can then
`be updated, or it can be modi?ed to accommodate new
`software or new equipment, or it can be improved to
`provide management tools not contemplated by the
`designers of the agent.
`The foregoing description of the present invention
`has been presented for purposes of illustration and de
`scription. It is not intended to be exhaustive or to limit
`the invention to the precise form disclosed, and other
`modi?cations and variations may be possible in light of
`the above teachings. The embodiment was chosen and
`described in order to best explain the principles of the
`invention and its practical application to thereby enable
`others skilled in the art to best utilize the invention in
`various embodiments and various modi?cations as are
`suited to the particular use contemplated. It is intended
`that the appended claims be construed to include other
`alternative embodiments of the invention except insofar
`as limited by the prior art.
`What is claimed is:
`1. In a computer system comprising a managing com
`puter and at least one managed computer, the managing
`computer and the managed computer connected by a
`network, the managed computer having an executable
`program and an agent, capable of receiving information
`from the managing computer, running as background
`software, the agent, while running, having a set of exe
`cutable functions de?ned by a collection of manage
`ment objects forming a management information base, a
`method for extending the set of executable functions of
`the running agent, the method comprising the following
`steps:
`a. de?ning a new management object in a text ?le in
`the managing computer, the new management ob
`ject associated with the executable program, the
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`text ?le including at least one object identi?cation
`f. interpreting the new management object de?ned by
`and a directory path for the executable program;
`the text ?le as an executable function, thereby ex
`b. sending the text ?le, over the network, from the
`tending the set of executable functions of the run
`managing computer to the managed computer;
`ning agent;
`c. sending a recon?gure command, over the network, 5
`whereby, if the managing computer sends an object
`from the managing computer to the agent;
`identi?cation which was included in the text ?le
`d. receiving the recon?gure command by the agent;
`over the network to the agent;
`e. appending the text ?le, by the running agent, to the
`i) the agent receives the object identi?cation;
`collection of management objects in the running
`ii) the managed computer executes the executable
`agent, in response to the recon?gure command; 10
`program indicated by the object identi?cation.
`and
`* * *
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