Why separate hosts and services

[Chris Wilson]

Hi all,

I have a question about the design of Nagios. I hope that it's not a 
stupid question or one that's been asked before. A little googling didn't 
show me anything useful.

Why is it that Nagios has separate concepts of hosts and services? Since
the only way to check that a host is up is to query some service on it,
why bother with hosts at all? Why not just consider a host to be the sum
of the service(s) that it implements, depending on one another and on
other host-services? Please could someone explain the rationale to me?

Also, I had an idea about grouping services together into meta-services or
super-services. One can imagine that if a service provided by a router is
"packet forwarding", the best way to determine if this service is up or
down is to examine the hosts (or services :-) below it. If they are all
down then packet forwarding is obviously down as well, and we should only 
get one notification.

Is there any way to configure this with Nagios? If so, then I apologise
for not asking the users list, but I have never seen such a facility. If
not, would it be difficult to add?

Cheers, Chris.
-- 
_  __ __     _
 / __/ / ,__(_)_  | Chris Wilson -- UNIX Firewall Lead Developer |
/ (_  ,\/ _/ /_ \ | NetServers.co.uk http://www.netservers.co.uk |
\__/_/_/_//_/___/ | 21 Signet Court, Cambridge, UK. 01223 576516 |



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