SNMP Graph with gaps

[salvarez]

Hello, I am new in Zabbix world and I am starting monitoring some of my lan devices.

I am running zabbix 2.4 on a Debian Weezy box

The problem I am suffering is related with monitoring an old 3Com 4900 switch which snmp v1 support

I have created 2 items to monitor InOctects and OutOctect on an specific Nic and I am getting correct values

I have created another item to add both previous values (InOctects + OutOctects) but the return value does not correspond with de sum of the individual items.

Configuration Item:

Type : snmp v1 agent
key: iface03In.key
snmp oid: 1.3.6.1.2.1.2.2.1.10.103
type of information: Numeric (float)
units : bps
Use custom multiplier: 8
Update interval: 40
Store value: Delta value (Speed per second)
Show value: As Is

Type : snmp v1 agent
key: iface03Out.key
snmp oid: 1.3.6.1.2.1.2.2.1.16.103
type of information: Numeric (float)
units : bps
Use custom multiplier: 8
Update interval: 40
Store value: Delta value (Speed per second)
Show value: As Is

This last item is a "calculate item" and I am using the following formula to try to calculate the value:

last("iface03Out.key") + last("iface03In.key")

Configuration item:

Type : calculated
key:BWiface03.key
type of information: Numeric (float)
units : bps
Use custom multiplier: 8
Update interval: 40
Store value: Delta value (Speed per second)
Show value: As Is

the result of this is a graphic with gaps in some moments and also what I think they are wrong values

Am I doing something wrong or could it be a switch problem?

Thanks in advance

[BDiE8VNy]

My first idea would be that one of the SNMP items used in the calculated item temporarily turn into unsupported state, what finally changes the calculated item into unsupported state as well.

There are several causes thinkable for that:

• https://support.zabbix.com/browse/ZBX-8538
• https://support.zabbix.com/browse/ZBX-8528
• Poller timeout exceeded
• ...