Electrical computers and digital processing systems: multicomput – Computer network managing
Reexamination Certificate
1998-04-30
2003-02-11
Caldwell, Andrew (Department: 2758)
Electrical computers and digital processing systems: multicomput
Computer network managing
C709S230000
Reexamination Certificate
active
06519635
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to simple network management protocol (SNMP) functions and, in particular, to a translation mechanism whereby SNMP protocol data units (PDUs) are converted to database records for use by SNMP agents.
BACKGROUND
The simple network management protocol (SNMP) is a network management standard protocol created, at least in part, under the guidance of the Internet Task Forces of the International Standards Organization. The SNMP operates within a network management system and is used to convey information about network elements among various “agents” in the system and a managing process. Within the SNMP hierarchy, the agents report to the managing process on the status of their respective managed network elements. In turn, the agents receive directions from the managing process on actions to perform on those network elements. A management information base (MIB) is used by the agents and the managing process to determine the structure and content of management information concerning the network elements. In other words, the MIB describes the managed network elements. The network elements may be represented by managed objects and may be hardware elements such as switches, private branch exchanges (PBXs), port carts within a switch or PBX, workstations, etc., or software elements such as queuing algorithms, buffer management routines, traffic policing routines, etc.
As illustrated in
FIG. 1
, within an SNMP framework, a managing system
10
directs the actions of a managed system
12
. The managed system
12
includes a remote manager
14
in addition to a number of managed objects
16
. The remote manager
14
generally includes an agent
18
, called an SNMP master agent, which is responsible for receiving network management messages
20
from a managing process
22
associated with the managing system
10
and ensuring that proper access control measures are taken regarding the managed objects
16
. The agent
18
may also be responsible for providing and controlling local logging operations and for making decisions about whether messages are to be returned to Managing process
22
. The messages
20
which may be passed between the managing process
22
and the agent
18
(and those which may be returned by the agent
18
) take the form of protocol data units (PDUs).
As discussed above, the managed objects
16
are representations of how a network resource can be managed by the management protocol; they are not “things” themselves. Instead, the managed objects
16
are abstractions of physical or logical network elements. Each managed object
16
can be described (defined) by attributes, which are characteristics or properties, at its interface; operations which can be performed on it; notifications or reports it is allowed to make; and its behavior in response to those operations. The attributes of each managed object
16
distinguish it from other managed objects within the network. Thus, the attributes describe the characteristics, current state, and operating conditions of the managed object
16
. Associated with each attribute is an attribute value, e.g., a card in a switch may be described by an attribute called “status” which may have values of “operational” and “not operational”. Thus, each attribute consists of a “type” and one or more values.
SNMP uses a relatively limited set of operations to perform its management functions. For example, “Gets” are used to retrieve information and “Sets” are used to modify information. Each Get request includes an identifier to distinguish it from other requests and to identify the network element about which information is requested. Gets are answered with a “Get Response” which includes an identifier to associate it with the appropriate Get request and the data requested thereby. Sets are used to describe an action to be performed on a network element, e.g., to change a value. In addition, “Traps” may be used to report unusual conditions or to change the status of a network element.
The management information base (MIB) is one of the most important components of the network management system because it identifies the network elements (i.e., it describes the managed objects
16
) that are to be managed. The MIB also contains the unique identifiers (addresses) that are to be associated with each managed object
16
. The MIB then, is a database that contains information about the managed objects
16
. For example, the MIB may contain information about the number of cells or packets sent or received across an interface or the number of connections on a port card of a switch in the network. Further, the MIB contains information that describes each network management user's ability to access elements of the MIB. For example, one user may have read-only privileges, while another may have read-write privileges.
In general, network management protocols operate on the MIB, rather than directly on the managed objects
16
. This level of abstraction allows the managed system
12
or managing system
10
to be ignorant of the database organization of a network element, because it operates only on the MIB, which represents the managed objects
16
. The systems operate through the exchange of messages
20
in the form of PDUs and the MIB describes the contents and structure of the fields that must be included within the PDUs. For example, the MIB defines the type and value fields for the Get and Set messages which are passed. The important aspects of the MIB then, are that it defines the network elements that are managed, how the user accesses them and how they can be reported.
FIG. 2
illustrates a conventional method of implementing SNMP in a distributed network. Typically, an SNMP master agent
30
, which is part of the managed system
12
, is placed on a main processor system and various SNMP sub-agents
32
, each with their associated MIBs
34
, are placed on (a) secondary processor system(s). An SNMP manager
36
(which generally includes the managing process for the network) exchanges SNMP PDUs (e.g., which may include Get, Set and/or Get Response messages)
38
with the SNMP master agent
30
, e.g., to provide control information for the SNMP master agent
30
or an SNMP sub-agent
32
associated therewith or to receive requested values of attributes.
The format of the SNMP PDUs is illustrated in FIG.
3
. As shown, each SNMP PDU
38
is encapsulated in a packet
40
which generally comprises a header
42
(e.g., an internet protocol header), which allows for appropriate flow and traffic control and routing within the distributed network, and a CRC field
44
, which allows for error checking. The SNMP PDU
38
may thus be regarded as a data packet which generally specifies the address
48
of the object to be controlled (e.g., the SNMP master agent
30
or an associated SNMP sub-agent
32
) the desired command (e.g., a Set or Get command)
50
and an appropriate value (e.g., an attribute value for a network element)
52
.
In conventional SNMP-controlled networks, the SNMP PDU
38
provided by the SNMP manager
36
to the SNMP master agent
30
must be parsed by the SNMP master agent
30
before it can be provided to an SNMP sub-agent
32
. The parsing allows the SNMP master agent
30
to determine the appropriate SNMP sub-agent to receive the command
50
and to reformat the SNMP PDU
38
provided by the SNMP manager
36
to a format which can be recognized by the associated SNMP sub-agent
32
. The SNMP master agent
30
, upon completion of these operations, packages and transmits a further protocol data unit, referred to as an Agent PDU
54
, to the appropriate SNMP sub-agent
32
. Even where the command
50
is destined for a network element associated with the SNMP master agent
30
, parsing operations are required to identify the address of the intended network object
16
.
The Agent PDU
54
generally resembles the SNMP PDU
40
illustrated in FIG.
3
and comprises header and data fields. Again, the data field will generally specify the address of the managed object
16
to
Carroll Mark
Champlin Michael
Caldwell Andrew
Cisco Technology Inc.
LandOfFree
SNMP master agent that translates messages to a sub-agent... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with SNMP master agent that translates messages to a sub-agent..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and SNMP master agent that translates messages to a sub-agent... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3179366