csup & portsnap

I'm going to use -stable and csup, so first i'm going to download "stable-supfile" and for ports tree "ports-supfile."
Now, to download ports-supfile or ports tree i'm going to use:
 csup -g -L 2 /root/ports-supfile
but, do i use same command for later to update ports tree, or not, it is not realy clear to me like portsnap, portsnap is using fetch, extract and update, for the first time, and later only fetch & update, what about csup..thanks!
I'd recommend you only use csup for the FreeBSD Sources, i.e. /usr/src. Portsnap is much faster and more efficient than csup on the ports tree.

Using portsnap for the first time you only need to do:
portsnap fetch extract
The next time that you need to update ports use:
portsnap fetch update

For csup, you use it just run the same command the first time and every subsequent time:
csup -g -L2 /root/ports-supfile
brd@, thank you very much for your explanation, i'm going to use your advice and stick at portsnap. :)
The reason i was going to use csup for updating ports is that i was thinking csup is better for -stable branch....i was reading somewhere or...i'm not sure, anyway, thanks one more time!
In a multi server environment I prefer to cvsup/portsnap to one server and then rsync o he rest, MUCH faster.