To aggregate the RX traffic on the links use the following code, it will aggregate interfaces 7 - 9.
round(rate(diff32(oid("1.3.6.1.2.1.2.2.1.10.7"))*8))+round(rate(diff32(oid("1.3.6.1.2.1.2.2.1.10.8"))*8))+round(rate(diff32(oid("1.3.6.1.2.1.2.2.1.10.9"))*8))
If you need to aggregate more than 3 links then keep adding the following code after another + symbol.
round(rate(diff32(oid("1.3.6.1.2.1.2.2.1.10.10"))*8))
Create a new data source with the code you have created and it will graph the aggregate RX of the links you have added in.
1.3.6.1.2.1.2.2.1.10.x will give you the RX of the port
1.3.6.1.2.1.2.2.1.16.x will give you the TX of the port
where x is the interface number.
Open Charts then click on the Data Source tab and create a data source as shown below...
Graph_aggregate_interfaces.jpg
Adjust the interval time and keep times to your needs.
If you want to also have the aggregate of the TX just create another Data Source and use the TX OID (1.3.6.1.2.1.2.2.1.16.x) rather than the RX OID and you can then create a chart with both of them visable.
Add a new chart and then add your two data sources as shown below.
Graph_aggregate_interfaces_chart.jpg
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