Method and system for detecting changes in a network using simple network management protocol polling

• US 9,473,348 B2
• Filed: 07/13/2015
• Issued: 10/18/2016
• Est. Priority Date: 05/23/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Sankaran, Ganesh Chennimalai
• Primary Examiner(s): Zong, Ruolei
• Application Number:
  US14/797,466
• Publication Number:
  US 20150319032A1
• Time in Patent Office: 463 Days
• Field of Search: 709/213, 709/223, 709/224, 370/254
• US Class Current: 1/1
• CPC Class Codes: H04L 41/0213 Standardised network management protocols, e.g. simple network management protocol [SNMP]
• CPC Class Codes: H04L 41/046 comprising network management agents or mobile agents therefor
• CPC Class Codes: H04L 43/10 Active monitoring, e.g. heartbeat, ping or trace-route

Abstract

In an embodiment, methods and systems have been provided for detecting changes in a network using improved Simple Network Management Protocol (SNMP) polling that reduces network traffic. Examples of changes in the network include, but are not limited to, configuration and behavioral changes in a network device, and response of network device to a network change. A Network Management Station (NMS) periodically polls Management Information Base (MIB) groups instead of periodically polling individual MIB object instances. The NMS receives the Aggregate Change Identifiers (ACIs) of MIB groups in response to polling, from a SNMP agent. The changes in the received ACIs represent the changes in the MIB groups. A change in an MIB group represents changes in the MIB object instances of the MIB group. The ACIs can be checksum, timestamp, and a combination of number of MIB object instances in a group and checksum of the MIB group.

Claims

1. A method comprising:

generating, at a network device, a plurality of first-level management information base (MIB) groups;

generating a plurality of subsets of MIB object instances, wherein each subset in the plurality of subsets includes a number of MIB object instances that is less than all MIB object instances in the network device;

for each MIB group in the plurality of first-level MIB groups, populating the MIB group with identifiers corresponding to MIB object instances that are included in one selected subset in the plurality of subsets, wherein each MIB group in the plurality of first-level MIB groups is associated with a different subset in the plurality of subsets;

generating, at the network device, a second-level MIB group, wherein the second-level MIB group includes the plurality of first-level MIB groups;

receiving, from a network management server (NMS), a request for information associated with MIB object instances included in the network device;

responsive to receiving the request, determining, for each first-level MIB group, whether changes are made to the MIB object instances for which corresponding identifiers are included in the first-level MIB group;

based on a determination of a change in at least one MIB object instance associated with a particular first-level MIB group, modifying an existing aggregate change identifier (ACI) for the particular first-level MIB group, wherein an ACI is a checksum computed using configuration values of the MIB object instances corresponding to identifiers included in the associated first-level MIB group;

computing a first updated ACI for the particular first-level MIB group, wherein the first updated ACI is an incremental checksum that is computed using the existing ACI that is modified;

computing a second updated ACI for the second-level MIB group, wherein the second updated ACI is computed based on the first updated ACI for the particular first-level MIB group, and existing ACIs for remaining first-level MIB groups; and

sending the second updated ACI to the NMS.

2. The method of claim 1, the method further comprising:

generating, at the network device, a plurality of second-level MIB groups, wherein each second-level MIB group in the plurality of second-level MIB groups includes a subset of first-level MIB groups such that the subset of first-level MIB groups included in a second-level MIB group is different from the subsets of first-level MIB groups included in other second-level MIB groups; and

generating, at the network device, a third-level MIB group, wherein the third-level MIB group includes the plurality of second-level MIB groups.

3. The method of claim 1, wherein modifying the existing ACI for the particular first-level MIB group further includes marking as invalid the ACI for the particular first-level MIB group.

4. The method of claim 1, further comprising:

based on a determination that none of the MIB object instances has changed since a previous time at which existing ACIs were computed for the first-level MIB groups, sending the existing ACI for the second-level MIB group to the NMS.

5. The method of claim 1, wherein generating a plurality of subsets of MIB object instances further comprises:

for each subset in the plurality of subsets, selecting MIB object instances based on a table compression factor, the table compression factor being equal to a number of MIB object instances that are grouped to form a first-level MIB group.

6. A non-transitory machine-readable medium including a plurality of instructions for execution by at least one processor, the plurality of instructions when executed cause the at least one processor to perform operations including:

generating, at a network device, a plurality of first-level management information base (MIB)groups;

generating a plurality of subsets of MIB object instances, wherein each subset in the plurality of subsets includes a number of MIB object instances that is less than all MIB object instances in the network device;

for each MIB group in the plurality of first-level MIB groups, populating the MIB group with identifiers corresponding to MIB object instances that are included in one selected subset in the plurality of subsets, wherein each MIB group in the plurality of first-level MIB groups is associated with a different subset in the plurality of subsets;

generating, at the network device, a second-level MIB group, wherein the second-level MIB group includes the plurality of first-level MIB groups;

receiving, from a network management server (NMS), a request for information associated with MIB object instances included in the network device;

responsive to receiving the request, determining, for each first-level MIB group, whether changes are made to the MIB object instances for which corresponding identifiers are included in the first-level MIB group;

based on a determination of a change in at least one MIB object instance associated with a particular first-level MIB group, modifying an existing ACI for the particular first-level MIB group, wherein an ACI is a checksum computed using configuration values of the MIB object instances corresponding to identifiers included in the associated first-level MIB group;

computing a first updated aggregate change identifier (ACI) for the particular first-level MIB group, wherein the first updated ACI is an incremental checksum that is computed using the existing ACI that is modified;

computing a second updated ACI for the second-level MIB group, wherein the second updated ACI is computed based on the first updated ACI for the particular first-level MIB group, and existing ACIs for remaining first-level MIB groups; and

sending the second updated ACI to the NMS.

7. The non-transitory machine-readable medium of claim 6, the plurality of instructions when executed configured to cause the at least one processor to perform operations including:

generating, at the network device, a plurality of second-level MIB groups, wherein each second-level MIB group in the plurality of second-level MIB groups includes a subset of first-level MIB groups such that the subset of first-level MIB groups included in a second-level MIB group is different from the subsets of first-level MIB groups included in other second-level MIB groups; and

generating, at the network device, a third-level MIB group, wherein the third-level MIB group includes the plurality of second-level MIB groups.

8. The non-transitory machine-readable medium of claim 6, wherein modifying the existing ACI for the particular first-level MIB group further includes marking as invalid the ACI for the particular first-level MIB group.

9. The non-transitory machine-readable medium of claim 6, wherein based on a determination that none of the MIB object instances has changed since a previous time at which the existing ACIs were computed for the first-level MIB groups, the existing ACI for the second-level MIB group is sent to the NMS.

10. The non-transitory machine-readable medium of claim 6, wherein generating a plurality of subsets of MIB object instances comprises:

for each subset in the plurality of subsets, selecting MIB object instances based on a table compression factor, the table compression factor being equal to a number of MIB object instances that are grouped to form a first-level MIB group.

11. An apparatus comprising:

a processor; and

a memory storing a plurality of instructions for execution by the processor, the plurality of instructions when executed cause the processor to perform operations including;

generating a plurality of first-level management information base (MIB)groups;

generating a plurality of subsets of MIB object instances, wherein each subset in the plurality of subsets includes a number of MIB object instances that is less than all MIB object instances in the network device;

for each MIB group in the plurality of first-level MIB groups, populating the MIB group with identifiers corresponding to MIB object instances that are included in one selected subset in the plurality of subsets, wherein each MIB group in the plurality of

first-level MIB groups is associated with a different subset in the plurality of subsets;

generating a second-level MIB group, wherein the second-level MIB group includes the plurality of first-level MIB groups;

receiving from a network device a request for information associated with MIB object instances;

responsive to receiving the request, determining, for each first-level MIB group, whether changes are made to the MIB object instances for which corresponding identifiers are included in the first-level MIB group;

based on a determination of a change in at least one MIB object instance associated with a particular first-level MIB group, modifying an existing ACI for the particular first-level MIB group, wherein an aggregate change identifier (ACI) is a checksum computed using configuration values of the MIB object instances corresponding to identifiers included in the associated first-level MIB group;

computing a first updated ACI for the particular first-level MIB group, wherein the first updated ACI is an incremental checksum that is computed using the existing ACI that is modified;

computing a second updated ACI for the second-level MIB group, wherein the second updated ACI is computed based on the first updated ACI for the particular first-level MIB group, and existing ACIs for remaining first-level MIB groups; and

sending the second updated ACI to the network device.

12. The apparatus of claim 11, the plurality of instructions when executed configured to cause the processor to perform operations including:

generating, at the network device, a plurality of second-level MIB groups, wherein each second-level MIB group in the plurality of second-level MIB groups includes a subset of first-level MIB groups such that the subset of first-level MIB groups included in a second-level MIB group is different from the subsets of first-level MIB groups included in other second-level MIB groups; and

generating, at the network device, a third-level MIB group, wherein the third-level MIB group includes the plurality of second-level MIB groups.

13. The apparatus of claim 11, wherein modifying the existing ACI for the particular first-level MIB group further includes marking as invalid the ACI for the particular first-level MIB group.

14. The apparatus of claim 11, wherein based on a determination that none of the MIB object instances has changed since a previous time at which the existing ACIs were computed for the first-level MIB groups, the existing ACI for the second-level MIB group is sent to the NMS.

15. The apparatus of claim 11, wherein generating a plurality of subsets of MIB object instances comprises:

for each subset in the plurality of subsets, selecting MIB object instances based on a table compression factor, the table compression factor being equal to a number of MIB object instances that are grouped to form a first-level MIB group.