Most network monitoring systems don’t dig deep enough into the network to see all of the error counters.
With most network monitoring software packages, if you look at an interface, it might show as healthy because the one or two error counters that it tracks might be zero. The monitoring software lulls you into a false sense of comfort thinking that the interface is healthy, when it is not.
If you login to the web UI of the switch, it may show a few more error counters. The CLI has many more error counters and packet buffer counters that are presented, but this is still not the whole story.
Most switch and router manufacturers include all the error counters via SNMP since it is easy for them to map the errors to SNMP variables. This means that the richest dataset is only available via SNMP. The problem with this is that you have to know where to look for the SNMP OIDs to find the errors, and then validate that the switch/router manufacturer supports these error counters and is providing valid data for each counter. A lot of work goes into finding error counters on just one interface of one device, and the work multiplies when you have hundreds of devices, each with 50 or more interfaces.
When the monitoring systems don’t dig deep enough into all the error counters, you’re stuck not knowing the truth if a network interface is healthy or not. Essentially, you don’t know what you aren’t told. You can have an interface dropping a ton of packets due to collisions, FCS Errors, Alignment Errors, runt packets, giant packets, and many other reasons. Nevertheless, that monitoring software would say that the interface is perfectly healthy.
This is one reason why network professionals think that their network is healthy, and at the same time users suffer from strange slowdowns, glitches, and hiccups that affect web, UC, VoIP, and video communications.
PathSolutions TotalView automatically collects 19 errors counters, QoS, configuration, and performance information from every interface on the network so that Total Network Visibility® can be achieved. For more information, see the list of SNMP error counters across the network that TotalView tracks.
See also: How to Diagnose and Fix Packet Loss.