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Appendix C      Event Correlation Examples
  Correlation Scenarios
Figure C-16 BGP Process Down Causes Several Events
For the event [BGP Neighbor Loss, RR2]:
Additional Collected Events: [BGP Process Down, RR2], [BGP Neighbor Loss, RR2].
Root cause: Correlates to [BGP Process Down, RR2].
Figure C-17 displays the events identified by the system in this scenario.
Figure C-17 BGP Process Down Correlation
BGP process down
RR2-IOU-176
RR2-IOU-176 : 169.254.......

 
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Appendix C      Event Correlation Examples
  Correlation Scenarios
BGP Link Down Scenarios
Figure C-18 illustrates the lab setup for the BGP Link Down scenarios described in this topic.
Figure C-18 Lab Setup for BGP Link Down Scenarios
Figure C-19 illustrates the lab setup for the scenarios with only the BGP links displayed.
Figure C-19 Lab Setup for Scenarios with Only the BGP Links Displayed
The VNE models the BGP connection between routers and actively...

 
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Appendix C      Event Correlation Examples
  Correlation Scenarios
A BGP link might be disconnected in the following scenarios:
The BGP process on a certain device goes down, causing all the BGP links that were connected to 
that device to disconnect.
A physical link (path) is disconnected, causing one side of the logical BGP link to become 
unreachable.
A device becomes unreachable, due to reload or shutdown. This causes all the links to the device to 
be...

 
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Appendix C      Event Correlation Examples
  Correlation Scenarios
Prime Network Failure Processing
Event Identification
The following service alarms are generated by the system:
[BGP Link Down, RR2 < > PE-North-West] event. This event might be revealed in one of two ways: 
–After polling, changes are found in the BGP neighbor list in the device. 
–Syslogs suggest that something has changed in the device’s BGP neighbors or process. 
This alarm causes an...

 
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Appendix C      Event Correlation Examples
  Correlation Scenarios
Figure C-21 BGP Link Down Correlation to the Root Cause of Physical Link Down
Clearing Phase
A BGP Link Up event arrives when the root cause event is fixed so that the network is repaired. This 
clearing event is created after a clearing syslog arrives or after the next polling result reestablishes the 
BGP connection.
Link down due to admin down
P-North-IOU-176#0:Seri...
P-North-IOU-176...

 
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Appendix C      Event Correlation Examples
  Correlation Scenarios
Figure C-22 displays the up event that clears all tickets identified by the system.
Figure C-22 BGP Link Up Clears All the Tickets
Variation
In a managed network, the following events might be identified in addition to the BGP Link Down event:
BGP Process Down.
Device Unreachable.
BGP Process Down
Figure C-23 displays the scenario where a BGP Process Down event causes BGP Link Down events.
Link...

 
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Appendix C      Event Correlation Examples
  Correlation Scenarios
Figure C-23 BGP Process Down Causes BGP Link Down Events
For the event [BGP Link Down, RR2 < > PE-North-West]:
Additional Collected Events: [BGP Process Down, RR2].
Root cause: Correlates to the event [BGP Process Down, RR2].
Figure C-24 displays the events identified by the system in this scenario.
Figure C-24 BGP Process Down Correlation
BGP process down
RR2-IOU-176
RR2-IOU-176 : 169.254.......

 
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Appendix C      Event Correlation Examples
  Correlation Scenarios
Device Unreachable
For the event [BGP Link Down, RR2 < > PE-North-West]: 
Additional Collected Events: [Device Unreachable, RR2].
Root cause: Correlates to [Device Unreachable, RR2].
In an unmanaged network core (as illustrated in Figure C-25), the following events might be identified 
in addition to the BGP Link Down event:
BGP Process Down.
Device Unreachable.
Figure C-25 Lab Setup with...

 
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Appendix C      Event Correlation Examples
  Correlation Scenarios
BGP Process Down
NoteThe BGP Process Down event occurs on the managed PE-South.
In Figure C-26, the BGP Process Down event on PE-South causes BGP Link Down events. The relevant 
devices are PE-South, RR1, and RR2.
Figure C-26 BGP Process Down on PE-South Causes BGP Link Down Events
For the event [BGP Link Down, PE-South < > RR2]:
Additional Collected Events: [BGP Process Down, PE-South] and
[BGP...

 
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Appendix C      Event Correlation Examples
  Correlation Scenarios
Device Unreachable
For the Device Unreachable event, one or more PEs report on BGP connectivity loss to a neighbor that 
is unreachable.
In Figure C-28, the Device Unreachable on an unmanaged core causes multiple BGP Link Down events. 
The relevant devices are RR2 (Device Unreachable), RR1, PE-East, and PE-South.
Figure C-28 Device Unreachable on Unmanaged Core Causes Multiple BGP Link Down...