Cisco Systems 3.6 specifications Multi Route Correlation Example

Chapter 4 Advanced Correlation Scenarios

Multi Route Correlation

Multi Route Correlation

The correlation mechanism supports multi route scenarios, thereby eliminating false correlation, and guaranteeing that the correct root cause alarm is reported.

The correlation mechanism ensures that if multi-route segments exist then all the alarms found on a certain path (after eliminating invalid paths) are collected into an alarm set. These alarm sets are input into a multi route filtering algorithm which eliminates irrelevant alarms from these sets, and outputs the potentially root cause alarms. The root-cause alarm is determined from this group.

Multi Route Correlation Example 1

In this example, a link went down in the multi route segment between P1 and P4, and another link went down in the single route segment between P6 and PE2. As a result, CE1 lost connectivity to its management port, and became unreachable.

Figure 4-10 Multi Route Correlation Example 1

Device
unreachable	P2	P3	Link down
			#2

CE1PE1P1 Link down

#1

P4

P6PE2

P5

MNG core MNG core

182428

In this case the system will provide the following report:

•Root cause—Device Unreachable. Link Down #2 is identified as the root-cause for Device Unreachable (CE1).

Note Link Down #1 is not the root-cause of the alarm because after it occurs there is still an alternative route from CE1 to its management port.

Multi Route Correlation Example 2

In this example, there are traffic engineering routes (RSVP) from router CE2, so that CE2 can reach P1 through only three possible paths, namely:

•CE2->PE3->P7->P8->P1

•CE2->PE3->P8->P1

•CE2->PE3->P7->P1

Several links went down, and as a result, router CE2 became unreachable.

	Cisco Active Network Abstraction Fault Management User Guide, Version 3.6 Service Pack 1
OL-14284-01		4-11