How to sum traffic from multiple interfaces ?

[OgeeN]

Hello,
I would like to perform following task: I use cacti to monitor multiple interfaces on our switches. Each port has its own traffic graph with inbound and outbound traffic. Now I would like to sum inbound traffic from some of my graphs and make separate graph that would show sum of inbound traffic of e.g. three different interfaces and sum of outbound traffic from the same three interfaces.
For example:
Current inbound traffic on port1 is 1000 kbit/s, current inbound traffic on port2 is 1500 kbit/s. Now I want to make graph that would show that the sum of current inbound traffic of port1 and port2 is 2500 kbit/s.

Is there a way how to make this possible within cacti? I tried to use aggregate plugin but it performs different task.

Thanks for help

[fmangeant]

Hi

you can create a new graph template, add a graph using "None" as host and then you'll be able to choose datasources from various hosts.

[OgeeN]

OK, and is it possible to sum data from those datasources ?

UPDATE: This doesnt work. I created graph template with two lines and to each line I asigned two data sources. In resulting graph there were ohnly data from one data source. I think that I need some function that wil make sum of data from two different data sources.

[stonedar]

Hello,

Try creating a CDEF (under Graph Management) to sum them up:

CDEF Type = Custom String
CDEF Item Value = a,b,+,8,*

Assuming your graph items were labeled 'a' and 'b'.

then add a new graph item with None as data source (pick line/area and color) and select the defined CDEF function.