Mirroring only a few architectures

[PCextreme - Updates <updates@pcextreme.nl>]

Hi,

I work at a ISP where we use a lot of Debian servers.

At the moment we use ftp.nl.debian.org, but when we are updating our +/- 
400 Debian servers, it generates a lot of traffic.

So i fixed a server with some storage and started syncing with 
ftp.nl.debian.org

Now i found that it mirrors all architectures, but we only use i386.

When i was searching the web i saw that there are mirrors who only host 
a few architectures.

Now my question is, how is this done? What do i have to include/exclude 
when using rsync?

Does anyone have an example of this rsync commands?

Also, i don't need the sources, i only need the binaries.

I hope someone can provide me an example :)

Thank you in advance,

Wido den Hollander