Interaction RRDtool, snmp and cacti

[Amerillo]

Hello,

I have one question to, can anybody tell my how rrd-tool, snmp and cacti work together?
At the moment I'm installing a Web-Server with cacti, that is no problem, but
I haven't understand yet, how these 3 tools (cacti, rrdtool an net-snmp) associates together!

Can you help me, and describe the interaction?

Greetings

Amerillo

[BSOD2600]

Cacti brings together rrdtool, snmp, scripts etc into an easy interface for monitoring devices.

For example, a devices traffic is polled via SNMP. the output is then stored (via rrdtool) to its rra file. When you look at the graph, rrdtool looks into the rra file and creates it for you.