Perform a calculation on discoverable items

[chris.noon]

I am creating Zabbix templates for network devices and have 95% of what I need working.

I can poll a single MIB.
I can poll multiple MIB's and perform calculations on the return values.
I can discover MIB elements (e.g. interface ID's) and then use this to return values such as interface status or throughput for each interface.

I am now stuck on a specific device issue and I'm hoping Zabbix can help me work around it.

I use the discover feature to discover all the interfaces. I then probe the device to give me the throughput of the interfaces. This works flawlessly on any other device. The issue with this device is, the MIB doesn't return the throughput per second but instead the total traffic to have ever run through the interface. So the calculation I need is:

Current value minus the last recorded value

If I were using static MIB's I could do this, but I want to utilise the discovery method as I have a number of these devices and they all differ. So I want to discover the interface and then using Item prototypes probe the device while performing a calculation.

Can this be done?

[splitek]

So the calculation I need is:

Current value minus the last recorded value

https://www.zabbix.com/documentation/4.0/manual/config/items/item#item_value_preprocessing

Simple change

Calculate difference between the current and previous value. Evaluated as value-prev_value, where value - current value; prev_value - previously received value This setting can be useful to measure a constantly growing value. If the current value is smaller than the previous value, Zabbix discards that difference (stores nothing) and waits for another value. Only one change operation per item is allowed.