Cisco Systems 3.6 specifications Device Fault Identification, Device Unreachable Example

Chapter 4 Advanced Correlation Scenarios

Device Unreachable Alarm

Device Fault Identification

When a network element stops responding to queries from the management system, one of two things has happened:

•Connectivity to that device is lost.

•The device itself crashes or restarts.

Cisco ANA implements an algorithm that uses additional data to heuristically resolve the ambiguity and declare the root cause correctly. Refer to the following examples:

•Device Unreachable Example 1

•Device Unreachable Example 2

Device Unreachable Example 1

In this example, the router (R1) goes down. As a result the links, L2, L3, and L4 go down in addition to the R1 session.

Figure 4-1

ANA Unit

Device Unreachable Example 1

L1	SW1
	L2	R1

L3L4

Physical links Management connectivity

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In this case the system will provide the following report:

•Root cause—Device Unreachable (R1)

•Correlated events:

–L2 down

–L3 down

–L4 down

Device Unreachable Example 2

In this example, the router (R1) goes down. As a result the links, L2, L3, and L4 go down as well as the R1 session. The router R2, accessed by the link L3 is also unreachable.

Note No link-down alarm is displayed for L3 as its state cannot be determined.

Cisco Active Network Abstraction Fault Management User Guide, Version 3.6 Service Pack 1

4-2 OL-14284-01