Viewing network errors
The Vital Signs tool gives you a complete snapshot of errors witnessed during current network activity.
The Network Vital Signs tool informs you at a glance as to network error conditions and their severity, with respect to traffic conditions, by combining graphical shapes with specific color codes.
To view network vital signs, like error occurrences:
On the Classic tab, in the Statistics group, click Vital Signs.
 
Click the View button to choose a different layout, or click Settings to further customize said layouts. Most importantly, changes can be made to the update interval of the graph view and to thresholds of the plot view.
Results can be saved in a comma delimited file using File > Save > Save Data.
If you are using an Ethernet network and are worried that errors may be traversing the network, yet this tool has not detected any, ensure that your NIC’s NDIS driver can indeed recognize errors. To check driver error support, choose Options > Selected Probe or SNMP Device Properties, and click the Parameters tab.
After you are familiar with your network's “signature,” you will be able to immediately notice spikes in utilization and error activity as they occur. If you see an unusual divergence from the typical Vital Signs signature for your network, you can then use Network Errors by Station to pinpoint the source of the anomaly.
Color codes
Yellow lines anywhere in the display represent an idle condition. In other words, no matter what your display is telling you, activity is so low that the errors are not statistically important.
Green lines show normal network activity and error counts.
Red lines indicate error counts out of normal range.
Red lines are displayed when the following default error counts are encountered. Whenever a red line (i.e. a critical condition) is displayed, all of the formerly green lines turn blue to highlight the network state.
Utilization goes over 35%.
CRC & packets too small represent more than 25% of the total traffic.
Packets too big represent over 1% of total traffic.
Gray “shadows” show you an image of the reading taken immediately before the current reading.
 
About Vital Signs’ broadcasting LLC Exploratory packets
 
Vital Signs sends exploratory LLC packets when running the collision test. When the collision test option is on, Observer bursts 100 exploratory LLC packets per second, addressed to 00:00:FF:FF:FF, and listens for packet collisions. On a 1 Gb network this uses 0.004% of the network’s bandwidth and significantly less on a 10 Gb network. Collision testing is generally only run when a collision problem is suspected, although it can be run routinely at your discretion. If you turn off Vital Signs, then Observer will be completely passive and not send any LLC packets.