Missing dot3Stat data from many devices??

[brian.atkins]

We had an interesting problem. We are running 5 minute data collection on many devices and interfaces on both the ifTable and dot3StatTable. For several data collection intervals we continue to collect data from the ifTable, but had no data returned from the dot3StatTable!

Now, this was across many devices and interfaces. Is it possible that some networking event could cause the IOS agent to not report data for dot3Stat, such as a change to the spanning tree or something?

Not a lot more information on the devices (switch vs. router, for example), or IOS versions. These are all 10/100 Ethernet ports being monitored.

Thanks!

[jreekers]

Hi Brian.

The ifTable and dot3StatsTable report different things.

.1.3.6.1.2.1.2.2

ifTable OBJECT-TYPE

-- FROM IF-MIB

DESCRIPTION "A list of interface entries. The number of entries

is given by the value of ifNumber."

::= { iso(1) org(3) dod(6) internet(1) mgmt(2) mib-2(1) interfaces(2) 2 }

and

.1.3.6.1.2.1.10.7.2

dot3StatsTable OBJECT-TYPE

-- FROM ETHERLIKE-MIB

DESCRIPTION "Statistics for a collection of ethernet-like

interfaces attached to a particular system.

There will be one row in this table for each

ethernet-like interface in the system."

::= { iso(1) org(3) dod(6) internet(1) mgmt(2) mib-2(1) transmission(10) dot3(7) 2 }

Do you think it's possible that for those devices that aren't reporting anything for dot3StatsTable, they don't have interfaces that meet the parimeters of that object?

[Joe Clarke]

I assume from your description that most polling cycles DO return valid dot3StatsTable data from these same devices for these same ports, correct? If so, what do you mean when you say the data is missing for several intervals? Do you get zeros when you expect actual data, does the agent returns SNMP errors, or do you just get no response?

The exact list of objects being polled as well as the device type and IOS version for one affected device would be helpful.