Accumulate network traffic daily

Dear all,
I use metricbeat to collect the running information of the server and then store the data in Elasticsearch. I want to count the network accumulated traffic of each server each day. What should I do?
I wanted to integrate the network velocity, but grafana doesn’t seem to support integration.
I’ve also tried subtracting (the end of the day) from (the end of the day), but I don’t know how to get for a certain moment in grafana.
Do you have any good ideas you can share with me?