[collectd] interval in network packets?

[Thorsten von Eicken]

Stupid question: what is the interval in network packets used for? I 
would think that the only interval that matters in the end is the one 
defined in the RRDs. Does collectd do any combining of values within an 
interval? Does the interval in the network packets have to match the one 
used in the final RRD or else inaccuracies result? I tried to look at 
the code, but didn't arrive at any good conclusion. Thanks!
TvE