On Fri, Jan 07, 2005 at 12:23:48PM +0800, Joe Shen wrote:
Hi,
is there any recommended method to measure overall network availability?
The problem is, that most people have no definition when they consider their network available. And without that definition it seems impossible to monitor it. In the end it all comes down to defining service Levels which are acceptable. That might be as simple as defining how long round trip times are allowed to be (is a link packets need 16seconds to pass still available?) or as complicated as "is my network reachable from at least 99.8% of the ASes on the internet". Some things are easy to monitor, some are difficult, some are virtually impossible. Is your network still available if packets reach your webserver really fast from everywhere in the world, but the Firewall drops outgoing packets with source port 80? Technically the network is there, but practically it is unusable for many things. So availability might also be a value that is useless in real life. Nils