[syslog-ng] organizing logs over network

[westlake]

if i use source-> system(facility(local0)); and use an application that 
sends to local0, what's the most effective way of categorizing this into 
a special log file if the destination is over network?

I'm using two dns machines and they both send output to one logging 
machine.  So far I'm using the host() directive with filter{} and two 
log{} entries on the recipient, this way I can create a log depending on 
the ip.  Is there a better way to organize the logs instead of using 
host() with filter{} ?

thanks