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Chapter 2 Fault Detection and Isolation
Unreachable Network Elements
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| Unreachable Network Elements (continued) |
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VNE Type | Checks reachability using | When the NE fails to respond | When the NE is reachable | ||
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Generic | • | SNMP only (default). | General polling is suspended, and a VNE | • General polling is restarted. | |
VNE |
| During the SNMP test the | Unreachable alarm is sent to the | • The first time the VNE is | |
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| unit’s “SNMP get” the | Cisco ANA Gateway. Only the | ||
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| started, all the commands are | ||
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| sysoid of the NE and | reachability tests are executed thereafter to |
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| submitted to the queue, and the | ||
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| expects to receive a | detect when the device is reachable again. |
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| collector initiates an | ||
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| response |
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| If more than one protocol is used, it is |
| immediate session with the | |
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| or | enough for one of them to become |
| NE. The commands are sent to |
| • | SNMP only (default), | unreachable in order to generate the alarm. |
| the NE in a serial fashion. |
| The alarm is generic to all the protocols. |
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| and adding an ICMP test. | • | The alarm is cleared. | |
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Full VNE | • | SNMP only (default). | General polling is suspended, and a VNE | • The first time the VNE is | |
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| During the SNMP | Unreachable alarm is sent to the |
| started, all the commands are |
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| reachability test, the | Cisco ANA Gateway. Only the |
| submitted to the queue and the |
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| VNE polls the device’s | reachability tests are executed thereafter to |
| collector initiates an |
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| SysOID MIB using a | detect when the device is reachable again. |
| immediate session with the |
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| standard “SNMP Get” | If more than one protocol is used, it is |
| NE. The commands are sent to |
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| command, and expects to |
| the NE in a serial fashion. | |
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| enough for one of them to become |
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| receive a response | unreachable in order to generate the alarm. | • | The alarm is cleared. |
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| or | The alarm is generic to all the protocols. |
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| • | SNMP only (default), |
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| and adding ICMP and |
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| Telnet. During the Telnet |
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| test the unit sends |
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| "Enter" via the open |
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| session and expects to get |
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| a prompt back. |
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Each of these scenarios have two possible settings in the registry, namely:
•track reachability (true/false). The default is true.
When this parameter is true reachabilty is tracked according to the specific protocol, for example, ICMP, SNMP, Telnet, and so on.
When this parameter is false then the test is not performed.
•lazy reachability (true/false). The default is false. This parameters determines whether there is a dedicated reachability command
When this parameter is true reachability is based on polling, and a dedicated command not activated.
When this parameter is false a dedicated SNMP command is activated, and this test verifies the response from a specific SNMP oid (sysoid is the default that can be changed).
Note Changes to the registry should only be carried out with the support of Cisco Professional Services.
Cisco Active Network Abstraction Fault Management User Guide, Version 3.6 Service Pack 1
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