User`s guide

Alarms and Traps

Setting Alarms

446 5967–9446

Example 2 The following example conﬁgures an alarm on broadcast packets. The

alarm triggers when the data source detects a high level of Ethernet

broadcast packets on the network, and rearms when the level of broad-

casts drops back to a more normal level.

Historical Statistics graphs indicate that the typical rate of broadcast

packets on this particular network segment is below 4 per second. Rarely

does the rate exceed 10 per second.

Lately, however, you’ve been seeing evidence of brief broadcast storms.

To narrow down the problem, you decide to create an unﬁltered packet

capture on a LanProbe, then conﬁgure an alarm to stop packet capture

when the broadcast rate reaches 10 per second. This way, you’ll be able to

look at the network trafﬁc immediately preceding the broadcast storm.

In addition, you’ll conﬁgure a trap to notify you when the alarm triggers.

You’ve already deﬁned a trap destination group, called “admin,” that

includes your OpenView NNM management station.

To conﬁgure this alarm with packet capture, follow these steps:

1 Use Protocol Analyzer to conﬁgure a packet capture instance called

“broadcast/alarm” on the LanProbe, with no ﬁlter, and with a circular

capture buffer. Start the instance.

2 Open the Alarms application for the LanProbe, and conﬁgure the

basics of a new alarm: description, monitored object of Ethernet

Statistics➤Broadcast Packets, and threshold of 10 units per second for

5 seconds. Set the trap destination group to admin, which was deﬁned

earlier.

3 Push the Options… button to display the advanced alarm parameters.

Set the rising and falling thresholds at 10 and 4, respectively.

4 Conﬁgure the other advanced options as appropriate.

Figure 93 on page 447 shows the relevant parts of the Conﬁgure Alarm

and Alarm Advanced Options windows for this alarm.